Photograph of a Least Bittern on a branch over water.

Cover photo by Mike Burrell.

About the Ontario recovery strategy series

This series presents the collection of recovery strategies that are prepared or adopted as advice to the Province of Ontario on the recommended approach to recover species at risk. The Province ensures the preparation of recovery strategies to meet its commitments to recover species at risk under the Endangered Species Act, 2007 (ESA) and the Accord for the Protection of Species at Risk in Canada.

What is recovery?

Recovery of species at risk is the process by which the decline of an endangered, threatened, or extirpated species is arrested or reversed, and threats are removed or reduced to improve the likelihood of a species' persistence in the wild.

What is a recovery strategy?

Under the ESA a recovery strategy provides the best available scientific knowledge on what is required to achieve recovery of a species. A recovery strategy outlines the habitat needs and the threats to the survival and recovery of the species. It also makes recommendations on the objectives for protection and recovery, the approaches to achieve those objectives, and the area that should be considered in the development of a habitat regulation. Sections 11 to 15 of the ESA outline the required content and timelines for developing recovery strategies published in this series.

Recovery strategies are required to be prepared for endangered and threatened species within one or two years respectively of the species being added to the Species at Risk in Ontario list. Recovery strategies are required to be prepared for extirpated species only if reintroduction is considered feasible.

What’s next?

Nine months after the completion of a recovery strategy a government response statement will be published which summarizes the actions that the Government of Ontario intends to take in response to the strategy. The implementation of recovery strategies depends on the continued cooperation and actions of government agencies, individuals, communities, land users, and conservationists.

For more information

To learn more about species at risk recovery in Ontario, please visit the Ministry of Natural Resources and Forestry Species at Risk webpage.

Recommended citation

Ontario Ministry of Natural Resources and Forestry. 2016. Recovery Strategy for the Least Bittern (Ixobrychus exilis) in Ontario. Ontario Recovery Strategy Series. Prepared by the Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario. v + 5 pp. + Appendix.

© Queen’s Printer for Ontario, 2016

ISBN 978-1-4606-8989-9 (HTML)
ISBN 978-1-4606-8993-6 (PDF)

Content (excluding the cover illustration and images in the appended federal recovery strategy) may be used without permission, with appropriate credit to the source.

Cette publication hautement spécialisée « Recovery strategies prepared under the Endangered Species Act, 2007 », n'est disponible qu'en anglais en vertu du Règlement 411/97 qui en exempte l'application de la Loi sur les services en français. Pour obtenir de l'aide en français, veuillez communiquer avec recovery.planning@ontario.ca.

Acknowledgments

We thank Doug Tozer of Bird Studies Canada and Chris Risley of Ontario Ministry of Natural Resources and Forestry, for providing information that assisted in the development of this recovery strategy addendum.

Declaration

The recovery strategy for the Least Bittern (Ixobrychus exilis) was developed in accordance with the requirements of the Endangered Species Act, 2007 (ESA). This recovery strategy has been prepared as advice to the Government of Ontario, other responsible jurisdictions and the many different constituencies that may be involved in recovering the species.

The recovery strategy does not necessarily represent the views of all of the individuals who provided advice or contributed to its preparation, or the official positions of the organizations with which the individuals are associated.

The goals, objectives and recovery approaches identified in the strategy are based on the best available knowledge and are subject to revision as new information becomes available. Implementation of this strategy is subject to appropriations, priorities and budgetary constraints of the participating jurisdictions and organizations.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy.

Responsible jurisdictions

Ontario Ministry of Natural Resources and Forestry
Environment and Climate Change Canada – Canadian Wildlife Service, Ontario
Parks Canada Agency

Executive summary

Executive summary of Ontario’s recovery strategy

The Endangered Species Act, 2007 (ESA) requires the Minister of Natural Resources and Forestry to ensure recovery strategies are prepared for all species listed as endangered or threatened on the Species at Risk in Ontario (SARO) List. Under the ESA, a recovery strategy may incorporate all or part of an existing plan that relates to the species.

The Least Bittern (Ixobrychus exilis) is listed as threatened on the SARO List. The species is also listed as threatened under the federal Species at Risk Act (SARA). Environment Canada prepared the Recovery Strategy for the Least Bittern (Ixobrychus exilis) in Canada in 2014 to meet its requirements under the SARA. This recovery strategy is hereby adopted under the ESA. With the additions indicated below, the enclosed strategy meets all of the content requirements outlined in the ESA.

The Critical Habitat section of the federal recovery strategy provides an identification of critical habitat (as defined under the SARA). Identification of critical habitat is not a component of a recovery strategy prepared under the ESA. However, it is recommended that the approach used to identify critical habitat in the federal recovery strategy be considered when developing a habitat regulation under the ESA.

Since the publication of the federal recovery strategy, survey efforts have resulted in the submission of new records of Least Bittern to the Natural Heritage and Information Centre (NHIC), some of which may occur outside the designated critical habitat. Pending verification, these new locations, beyond what are currently identified as critical habitat in the federal recovery strategy for the Least Bittern, should also be considered in developing a habitat regulation for the species.

Executive summary of Canada’s recovery strategy

The Least Bittern (Ixobrychus exilis) is North America’s smallest heron. It breeds in freshwater and brackish marshes with tall emergent plants interspersed with open water and occasional clumps of woody vegetation. The species was designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2001 and 2009, and has been listed with the same status under Schedule 1 of the Species at Risk Act (SARA) since 2003.

Around 2-3% of the estimated 43,000 North American pairs are found in Canada, where they are distributed throughout southern Manitoba, Ontario, Quebec, New Brunswick and possibly Nova Scotia. Because of the species' secretive habits and the difficulties of surveying its habitat, population size and trend estimates are imprecise.

Wetland loss and degradation as well as impaired water quality are the primary threats to the Least Bittern throughout its range. Other threats include regulated water levels, invasive species, collisions (with cars and man-made structures), recreational activities, and climate change.

There are unknowns regarding the feasibility of recovery of the Least Bittern. Nevertheless, in keeping with the precautionary principle, a recovery strategy has been prepared as per section 41(1) of SARA as would be done when recovery is determined to be feasible.

The population and distribution objectives for the Least Bittern are to maintain and, where possible, increase the current population size and area of occupancy in Canada. Broad strategies and approaches to achieve these objectives are presented in the Strategic Direction for Recovery section.

Critical habitat is partially identified for the breeding habitat. It corresponds to the suitable habitat within 500 m of records of breeding activity since 2001. A total of 115 critical habitat units are identified, 10 of which are located in Manitoba, 54 in Ontario, 48 in Quebec and 3 in New Brunswick. A schedule of studies outlines key activities to identify additional critical habitat at breeding, foraging, post-breeding dispersal, moulting and migration stopover sites.

One or more action plans will follow this recovery strategy and will be posted on the Species at Risk Public Registry by 2019.

Adoption of federal recovery strategy

The Endangered Species Act, 2007 (ESA) requires the Minister of Natural Resources and Forestry to ensure recovery strategies are prepared for all species listed as endangered or threatened on the Species at Risk in Ontario (SARO) List. Under the ESA, a recovery strategy may incorporate all or part of an existing plan that relates to the species.

The Least Bittern (Ixobrychus exilis) is listed as threatened on the SARO List. The species is also listed as threatened under the federal Species at Risk Act (SARA). Environment Canada prepared the Recovery Strategy for the Least Bittern (Ixobrychus exilis) in Canada in 2014 to meet its requirements under the SARA. This recovery strategy is hereby adopted under the ESA. With the additions indicated below, the enclosed strategy meets all of the content requirements outlined in the ESA.

Species assessment and classification

Table 1. Species assessment and classification of the Least Bittern (Ixobrychus exilis). The glossary provides definitions for the abbreviations within, and for other technical terms in this document.

Assessment Status
SARO list classification Threatened
SARO list history Threatened (2008),
Threatened – Not Regulated (2004)
COSEWIC assessment history Threatened (2009),
Special Concern (1988)
SARA schedule 1 Threatened (2009)
Conservation status rankings GRank: G5
NRank: N4B
SRank: S4B

Distribution, abundance and population trends

Section 3.2 of the federal recovery strategy for the Least Bittern (Appendix 1) provides a description of the population and distribution of Least Bittern in Ontario. Since the publication of the federal recovery strategy, many observations of Least Bittern have been reported to Ontario’s Natural Heritage Information Centre (NHIC) The NHIC has not yet processed these records, but there is a high probability some of them will become element occurrences. The locations on the following list may be outside the designated critical habitat shown in Appendix B of the federal recovery strategy for the Least Bittern (Appendix 1) and should be considered in developing a habitat regulation for this species.

New locations of Least Bittern that have been reported to the NHIC since the federal recovery strategy, and identification of critical habitat, was published are listed below. The following are recent observations that may become new element occurrences:

  • Algoma District – Echo Bay Marsh
  • Frontenac County – Howe Island, Johnson Bay
  • Frontenac County – Wolfe Island, Bayfield Bay
  • Halliburton County – Horseshoe Lake
  • Kawartha Lakes – Logan Lake
  • Kawartha Lakes – Queen Elizabeth II Wildlands Provincial Park
  • Lanark County – Appleton Wetland
  • Lanark County – McEwan Bay Wetland
  • Lanark County – Murphys Point Provincial Park, Black Creek
  • Leeds and Grenville – Leeder’s Creek Wetland Complex
  • Peel – Heart Lake area

These new locations should be considered when the Ontario Ministry of Natural Resources and Forestry proposes a habitat regulation.

A recent study by Tozer (2016) found a significant decline in occurrence rates for the Least Bittern in Great Lakes Marsh Monitoring Program survey sites over the past two decades. This may or may not be reflective of the population in the Ontario Great Lakes basin.

Habitat needs

Tozer (2016) reported that Least Bitterns are more likely to occupy and colonize larger wetlands compared to smaller ones, and Quesnelle et al. (2013) found that Least Bitterns are more likely to occupy wetlands with a high proportion of wetland cover in the surrounding landscape. Tozer (2016) also noted that high quality Ontario habitat for most declining marsh-dependent breeding birds consists of robust-emergent-dominated but interspersed wetlands free of Purple Loosestrife (Lythrum salicaria) and European Common Reed (Phragmites australis australis), with limited urban land use and a high proportion of wetlands in the surrounding landscape.

Threats to survival and recovery

Tozer (2016) suggests that invasive Purple Loosestrife and European Common Reed are a threat to most of southern Ontario’s declining marsh-dependent breeding bird species. Additional threats include Blue Cattail (Typha × glauca) if it results in a loss of open patches of deep water and interspersion, which are preferred by Least Bittern (Tozer et al. 2010).

Approaches to recovery

New information under the section on Threats To Survival And Recovery above is not discussed in the federal recovery strategy. The federal recovery strategy does not include recovery actions to address these threats. Therefore, consideration should be given to relevant recovery actions that would help to address these new threats when developing recovery initiatives for this species in Ontario.

Area for consideration in developing a habitat regulation

Under the ESA, a recovery strategy must include a recommendation to the Minister of Natural Resources and Forestry on the area that should be considered in developing a habitat regulation. A habitat regulation is a legal instrument that prescribes an area that will be protected as the habitat of the species. The recommendation provided below will be one of many sources considered by the Minister, including information that may become newly available following completion of the recovery strategy, when developing the habitat regulation for this species.

The Critical Habitat section of the federal recovery strategy provides an identification of critical habitat (as defined under the SARA). Identification of critical habitat is not a component of a recovery strategy prepared under the ESA. However, it is recommended that the approach used to identify critical habitat in the federal recovery strategy be considered when developing a habitat regulation under the ESA. Pending verification, the new locations noted above, beyond what is currently identified as critical habitat in the federal recovery strategy for the Least Bittern in Canada (Appendix 1), should also be considered in developing a habitat regulation for this species.

Glossary

Committee on the Status of Endangered Wildlife in Canada (COSEWIC): The committee established under section 14 of the Species at Risk Act that is responsible for assessing and classifying species at risk in Canada.

Committee on the Status of Species at Risk in Ontario (COSSARO): The committee established under section 3 of the Endangered Species Act, 2007 that is responsible for assessing and classifying species at risk in Ontario.

Conservation status rank: A rank assigned to a species or ecological community that primarily conveys the degree of rarity of the species or community at the global (G), national (N) or subnational (S) level. These ranks, termed G-rank, N-rank and S-rank, are not legal designations. Ranks are determined by NatureServe and, in the case of Ontario’s S-rank, by Ontario’s Natural Heritage Information Centre. The conservation status of a species or ecosystem is designated by a number from 1 to 5, preceded by the letter G, N or S reflecting the appropriate geographic scale of the assessment. The numbers mean the following:

1 = critically imperilled
2 = imperilled
3 = vulnerable
4 = apparently secure
5 = secure
NR = not yet ranked

Element occurrence: The basic unit of record for documenting and delimiting the presence and extent of a species on the landscape. It is an area of land and/or water where a species is, or was, present, and which has practical conservation value.

Endangered Species Act, 2007 (ESA): The provincial legislation that provides protection to species at risk in Ontario.

Species at Risk Act (SARA): The federal legislation that provides protection to species at risk in Canada. This act establishes Schedule 1 as the legal list of wildlife species at risk. Schedules 2 and 3 contain lists of species that at the time the Act came into force needed to be reassessed. After species on Schedule 2 and 3 are reassessed and found to be at risk, they undergo the SARA listing process to be included in Schedule 1.

Species at Risk in Ontario (SARO) List: The regulation made under section 7 of the Endangered Species Act, 2007 that provides the official status classification of species at risk in Ontario. This list was first published in 2004 as a policy and became a regulation in 2008.

References

Quesnelle, P.E., L. Fahrig, and K.E. Lindsay. 2013. Effects of habitat loss, habitat configuration and matrix composition on declining wetland species. Biological Conservation 160:200-208.

Tozer, D.C. 2016. Marsh bird occupancy dynamics, trends, and conservation in the southern Great Lakes basin: 1996 to 2013. Journal of Great Lakes Research 42:136-145.

Tozer, D.C., E. Nol, and K.F. Abraham. 2010. Effects of local and landscape-scale habitat variables on abundance and reproductive success of wetland birds. Wetlands Ecology and Management 18:679-693.

Appendix 1. Recovery strategy for the Least Bittern (Ixobrychus exilis) in Canada

Photo of Least Bittern.

Federal cover illustration: © Benoit Jobin, Environment Canada, Canadian Wildlife Service – Quebec Region.

Document information

Recommended citation

Environment Canada. 2014. Recovery Strategy for the Least Bittern (Ixobrychus exilis) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada. Ottawa. vi + 41 pp.

Additional copies

For copies of the recovery strategy, or for additional information on species at risk, including COSEWIC Status Reports, residence descriptions, action plans, and other related recovery documents, please visit the Species at Risk (SAR) Public Registry.

Également disponible en français sous le titre :
« Programme de rétablissement du Petit Blongios (Ixobrychus exilis) au Canada »

© Her Majesty the Queen in Right of Canada, represented by the Minister of the Environment, 2014. All rights reserved.

ISBN 978-1-100-19922-1
Catalogue no. En3-4/127-2015E-PDF

Content (excluding the illustrations) may be used without permission, with appropriate credit to the source.

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996) agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress within five years.

The Minister of the Environment and the Minister responsible for the Parks Canada Agency are the competent ministers for the recovery of the Least Bittern, a Threatened species listed in Schedule 1 of SARA, and have prepared this recovery strategy, as per section 37 of SARA. It has been prepared in cooperation with the Provinces of Manitoba, Ontario, Quebec, New Brunswick, and Nova Scotia.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Environment Canada, the Parks Canada Agency, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of the Least Bittern and Canadian society as a whole.

This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Environment Canada, the Parks Canada Agency, and other jurisdictions and/or organizations involved in the conservation of the species.

Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

Acknowledgments

This recovery strategy was prepared by Vincent Carignan and Benoit Jobin ((EC-CWS) - Quebec Region) based on an initial draft by Andrew Horn (Dalhousie University). Earlier drafts were reviewed by members of the National Least Bittern Recovery Team [Vincent Carignan, chair, Ron Bazin (EC-CWS – Prairie & Northern Region), Samara Eaton and Jen Rock (EC-CWS - Atlantic Region), Valerie Blazeski (Parks Canada Agency), Ken DeSmet (Manitoba Conservation), Kari Van Allen and Dave Moore (EC–CWS – Ontario Region), Jon McCracken (Bird Studies Canada), and Eva Katic (National Capital Commission)]; and former members of the recovery team [Laurie Maynard and Barbara Slezak (EC-CWS – Ontario Region), Mark McGarrigle (New Brunswick Department of Natural Resources), Todd Norris (Ontario Ministry of Natural Resources), Jennifer Stewart (formerly with EC-CWS – Atlantic Region) and Gershon Rother (formerly with the National Capital Commission)].

Other contributors provided comments on the recovery strategy: Manon Dubé and Ewen Eberhardt (EC-CWS – National Capital Region), Marie-José Ribeyron (formerly with EC-CWS – National Capital Region), Karine Picard, Alain Branchaud and Matthew Wild (EC-CWS – Quebec Region), Diane Amirault-Langlais and Paul Chamberland (formerly with EC-CWS – Atlantic Region), Marie-Claude Archambault, Angela Darwin, Angela McConnell, Krista Holmes, Jeff Robinson and Tania Morais (EC-CWS – Ontario Region), David Bland, Michael Patrikeev and Stephen McCanny (Parks Canada Agency), Corina Brydar and Sandy Dobbyn (Ontario Ministry of Natural Resources - Ontario Parks), Jodi Benvenuti, Vivian Brownell, Glenn Desy, Leanne Jennings, Chris Risley, Marie-Andrée Carrière, Shaun Thompson, Don Sutherland, Lauren Trute, Doug Tozer and Allen Woodliffe (Ontario Ministry of Natural Resources).

The following individuals provided information on Least Bittern populations and habitat distribution, population trends, life history, survey methods, as well as conservation and management: Nickolas Bartok, Isabelle Beaudoin-Roy, Heidi Bogner, Robert Bowles, Courtney Conway, Glenn Desy, Pierre Fradette, Jonathon French, Christian Friis, Stacey Hay, Gary Huschle, Rudolf Koes, Claudie Latendresse, Soch Lor, Paul Messier, Shawn Meyer, Frank Nelson, Sarah Richer, Dave Roberts, Luc Robillard, Tracy Ruta-Fuchs, François Shaffer, Peter Taylor, Guillaume Tremblay, as well as Breeding Bird Atlas and Marsh Monitoring Program volunteers, and birders in Manitoba, Ontario, Quebec and the Maritimes.

Finally, thanks is given to all other parties including Aboriginal organizations and individuals, landowners, citizens, and stakeholders who provided comments on the present document and/or participated in consultation meetings.

Executive summary

The Least Bittern (Ixobrychus exilis) is North America’s smallest heron. It breeds in freshwater and brackish marshes with tall emergent plants interspersed with open water and occasional clumps of woody vegetation. The species was designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2001 and 2009, and has been listed with the same status under Schedule 1 of the Species at Risk Act (SARA) since 2003.

Around 2-3% of the estimated 43,000 North American pairs are found in Canada, where they are distributed throughout southern Manitoba, Ontario, Quebec, New Brunswick and possibly Nova Scotia. Because of the species' secretive habits and the difficulties of surveying its habitat, population size and trend estimates are imprecise.

Wetland loss and degradation as well as impaired water quality are the primary threats to the Least Bittern throughout its range. Other threats include regulated water levels, invasive species, collisions (with cars and man-made structures), recreational activities, and climate change.

There are unknowns regarding the feasibility of recovery of the Least Bittern. Nevertheless, in keeping with the precautionary principle, a recovery strategy has been prepared as per section 41(1) of SARA as would be done when recovery is determined to be feasible.

The population and distribution objectives for the Least Bittern are to maintain and, where possible, increase the current population size and area of occupancy in Canada. Broad strategies and approaches to achieve these objectives are presented in the Strategic Direction for Recovery section.

Critical habitat is partially identified for the breeding habitat. It corresponds to the suitable habitat within 500 m of records of breeding activity since 2001. A total of 115 critical habitat units are identified, 10 of which are located in Manitoba, 54 in Ontario, 48 in Quebec and 3 in New Brunswick. A schedule of studies outlines key activities to identify additional critical habitat at breeding, foraging, post-breeding dispersal, moulting and migration stopover sites.

One or more action plans will follow this recovery strategy and will be posted on the Species at Risk Public Registry by 2019.

Recovery feasibility summary

In considering the criteria established by the Government of Canada (2009), unknowns remain as to the recovery feasibility of the Least Bittern. Nevertheless, in keeping with the precautionary principle, this recovery strategy has been prepared as per section 41(1) of SARA as would be done when recovery is determined to be feasible. This recovery strategy addresses the unknowns surrounding the feasibility of recovery.

  1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.

    Yes. Breeding individuals are currently distributed throughout the Canadian range as well as in the United States.

  2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.

    Yes. Sufficient wetland habitat is available to support the species at its current level. Unoccupied and apparently suitable habitat is also available and additional sites could become suitable after restoration efforts or wetland creation.

  3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.

    Unknown. The main threats to the species and its breeding habitat as well as methods to avoid or mitigate them are known. However, some of these methods need to be refined and tested in Canada. Furthermore, foraging, post-breeding dispersal, moulting and migration stopover sites have yet to be identified and the threats to those sites will need to be specified.

  4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.

    Unknown. Habitat stewardship, along with wetland management, restoration and creation techniques have proven to be effective for this species although specific management prescriptions need to be developed. Mitigating other threats, such as off-site effects on wetland habitat quality, however, will be a continuing challenge.

1. COSEWIC species assessment information

Date of assessment: April 2009
Common name (population): Least Bittern
Scientific name: Ixobrychus exilis
COSEWIC status: Threatened
Reason for designation: This diminutive member of the heron family has a preference for nesting near pools of open water in relatively large marshes that are dominated by cattail and other robust emergent plants. Its breeding range extends from southeastern Canada through much of the eastern U.S. Information on the population size and exact distribution of this secretive species is somewhat limited. Nevertheless, the best available evidence indicates that the population is small (about 3000 individuals) and declining (> 30% in the last 10 years), largely owing to the loss and degradation of high-quality marsh habitats across its range.
Canadian occurrence: Manitoba, Ontario, Quebec, New Brunswick and Nova Scotia
COSEWIC status history: Designated Special Concern in April 1988. Status re-examined and confirmed in April 1999. Status re-examined and designated Threatened in November 2001 and in April 2009.

2. Species status information

Canada has 2-3% of the Least Bittern reproductive pairs in North America. The species has been listed as Threatened under Schedule 1 of the Species at Risk Act (SARA) (S.C. 2002, c. 29) since 2003. In Quebec, it has been listed as Vulnerable under the Act respecting threatened or vulnerable species (R.S.Q., c. E-12.01) since 2009. In Ontario, it has been listed as Threatened on the Species at risk in Ontario list since 2004 and regulated under the Endangered Species Act, 2007 (S.O. 2007, C. 6) since 2008. As of August 2013, the species had not been listed in Manitoba, New Brunswick or Nova Scotia.

The International Union for the Conservation of Nature ranks the global population of the Least Bittern as "Least Concern" (BirdLife International, 2009). NatureServe (2010) conservation ranks for Canada and the United States vary widely as shown in Table 1.

Table 1. NatureServe (2010) Conservation Ranks for the Least Bittern1,2.

Rank Jurisdiction rank
Global (G) G5 (Secure)
National (N) Canada: N4B (Apparently Secure)
U.S.: N5B, N5N (Secure)
Sub-national (S) Canada: Manitoba (S2S3B) ; Ontario (S4B) ; Quebec (S2S3B); New Brunswick (S1S2B) ; Nova Scotia (SNRB)
U.S.: SH (Utah) ; S1 (California, Delaware, District of Columbia, Kentucky, Massachusetts, New Hampshire, Oregon, Pennsylvania, West Virginia) ; S2 (Arkansas, Colorado, Connecticut, Illinois, Kansas, Maine, Maryland, Michigan, Nevada, Ohio, Rhode Island, South Dakota, Tennessee, Vermont) ; S3 (Arizona, Indiana, Iowa, Mississippi, Missouri, New Jersey, New Mexico, New York, North Carolina, Virginia, Wisconsin)

11: Critically Imperiled; 2: Imperiled; 3: Vulnerable; 4: Apparently Secure; 5: Secure; H: possibly extirpated; NR: Not Ranked. B (following a number): Breeding; N (following a number): Non-breeding.

2In most states along the Gulf coast (e.g., Texas, Louisiana, Florida), where it is resident year-round, the species is not listed, and has been recently removed from the federal list of "Species of Management Concern" (USFWS, 2002).

3. Species information

3.1 Species description

Measuring about 30 cm and weighing 80 g, the Least Bittern is North America’s smallest heron (Kushlan and Hancock, 2005). It is brown and buffy overall, with broad buff streaks on its white underside, and a contrasting back and crown that is glossy black in adult males but lighter in females and juveniles. Buff wing patches, which are especially obvious when the bird flushes, distinguish this species from all other marsh birds. When disturbed, the bird uses a rail-like "rick-rick-rick-rick", otherwise its call consists of a repeated "coo-coo-coo" (Sibley, 2000). Further details are provided in the COSEWIC (2009) status report.

3.2 Population and distribution

Global population and distribution

During the nesting season, the Least Bittern can be found from southern Canada to South America, including the Caribbean. There are year-round resident populations in river valleys and coastal areas farther south to northern Argentina and southern Brazil (COSEWIC, 2009; Poole et al., 2009). Isolated migrant populations also breed in Oregon, California, and New Mexico (Figure 1). There are an estimated 43,000 pairs of Least Bitterns in North America (Delany and Scott, 2006).

The migratory routes of the Least Bittern are unknown, but it is presumed that they migrate in a broad front that is locally funneled by north-south oriented peninsulas and coasts such as found in the closely related Little Bittern (Ixobrychus minutus) of Eurasia (Nankinov, 1999). The distribution of the adults during the moulting phase needs further study but the timing of this phase (mid-September to mid-December) suggests it mostly takes place during migration (Poole et al., 2009).

Least Bitterns winter from California to Florida south to Mexico and Latin America. The winter habitat is poorly known, although the species is presumed to occupy brackish and saline swamps and marshes (Poole et al., 2009).

Figure 1. Global distribution of the Least Bittern (from COSEWIC, 2009).

Figure 1 shows the North American range of the Least Bittern, differentiating breeding range from wintering range and migrant populations from resident ones.

Canadian population and distribution

In Canada, the Least Bittern generally breeds south of the Canadian Shield in Manitoba, Ontario, Quebec, New Brunswick and possibly Nova Scotia (COSEWIC, 2009; Figure 2). The species has been reported as a vagrant in other provinces. The Canadian breeding population is estimated at 1,500 pairs (between 1000 and 2800; COSEWIC, 2009; Table 2).

Figure 2. Breeding distribution of the Least Bittern in Canada as of 2012.

Figure 2 shows the 2010 breeding distribution of the Least Bittern in Canada.

Dots indicate locations isolated from the known breeding range, but where birds have been observed during the breeding season (Canadian Wildlife Service, unpublished data). This figure does not take into account immature individuals, sub-adults and non-breeding adults.

Table 2. Estimated numbers of Least Bittern pairs and Breeding Bird Atlas occurrences in Canada.

Province Number of breeding pairs (estimated) (COSEWIC, 2009) Number of atlas blocks (100 km2) in which the species was detected
Manitoba ~ 200 Unavailable
Ontario >500 210 (during the 2001-2005 period, 2nd atlas); Cadman et al. (2007)
Quebec 200-300 38 (during the 2010-2012 period, 2nd atlas); Atlas des oiseaux nicheurs du Quebec (2012)
New Brunswick unknown 7 (during the 2005-2010 period, 2nd atlas); Bird Studies Canada (2009, 2010)
Nova Scotia unknown 0 (during the 2005-2010 period, 2nd atlas); Bird Studies Canada (2009, 2010)

Despite recent advances in methods to detect the species (Conway, 2009; Johnson et al. 2009, Jobin et al. 2013) which have led to increases in reported numbers of breeding individuals, there is a general consensus that the species has declined (Sandilands and Campbell, 1988; Austen et al., 1994; James, 1999; Environment Canada, 2007; Poole et al., 2009). In Canada, this tendency has been observed in the core of the species' range with an average annual decline of 10.6% (95% CI = -6.9% to -14.3%) in the Great Lakes Basin from 1995 to 2007 (Archer and Jones, 2009). An analysis of the data from the Ontario breeding bird atlases yielded a similar trend (-10%/year, 95% CI = -5% to -16%, 1995-2006; Cadman et al., 2007). Conversely, in the Lake Simcoe-Rideau region (Ontario), there were no significant changes in the probability of observation (Cadman et al., 2007).

3.3 Needs of the Least Bittern

Current understanding of the ecological needs of the Least Bittern may be biased because selection of study sites and associated findings may be influenced by how easily the sites can be accessed and surveyed. Furthermore, the species' apparent habitat needs might be distorted by limitations in what habitat is available now compared to historically.

3.3.1 Habitat and biological needs
Breeding period

In Canada, breeding habitats are occupied from early May to early September (Fragnier, 1995). They consist of freshwater and brackish marshes with dense, tall, robust emergent plants (mainly cattail Typha spp), interspersed with relatively shallow (10-50 cm) open water and occasional clumps of shrubby vegetation (Parsons, 2002; Hay, 2006; Budd, 2007; Jobin et al., 2007; Yocum, 2007; Griffin et al., 2009). Rehm and Baldassarre (2007) refer to these conditions as hemi-marsh.

Water levels approximating those of a natural regime are an important breeding habitat feature as high water levels can flood nests that are constructed just above the water, whereas low levels reduce food availability and facilitate predators' access to nests (Arnold, 2005).

Densities of Least Bitterns appear to be mostly affected by local conditions such as water depth, food abundance, vegetation type and cover availability rather than marsh area or marsh area within the surrounding landscape (Arnold, 2005; Tozer et al. 2010). Indeed, although Least Bitterns usually nest in larger marshes (> 5 ha), territorial individuals have been found in marshes as small as 0.4 ha (Gibbs and Melvin, 1990). The species can also be semi-colonial, particularly in highly productive habitats (Kushlan, 1973; Bogner, 2001; Meyer and Friis, 2008), where they can reach a density of up to five calling birds or nests per hectare (Arnold, 2005; Poole et al., 2009). Although typically territorial, no definitive information exists on territory size and home range for the Least Bittern. Bogner and Baldassarre (2002a) found that breeding individuals moved an average maximum distance of 393 m ± 36 SE between two points while Griffin et al. (2009) found an average maximum distance of more than 2,000 m for breeding individuals in Missouri.

The Least Bittern is a visual predator that forages for prey (e.g., small fish, tadpoles, molluscs, insects) in clear, shallow water near openings in the marsh vegetation, often from platforms it constructs by bending emergent vegetation (Poole et al., 2009). This foraging method probably explains why they prefer marshes interlaced with channels, such as those created by muskrats (Poole et al., 2009).

Non-breeding period

There is little information on ecological needs of Least Bitterns and habitat characteristics in moulting, post-breeding dispersal, migration and wintering sites, although it is presumed that they are similar to those of breeding habitats.

4. Threats

4.1 Threat assessment

Table 3. Threat assessment.

Habitat loss or degradation.

Threat Level of concern a Extent Occurrence Frequency Severityb Causal certaintyc
Wetland destruction and degradation High Widespread Current Recurrent High High
Impaired water quality Medium-High Widespread Current Continuous/ Recurrentd Moderate Medium
Regulated water levels Medium Local Current/ Unknown Recurrent/ Unknown High/ Low Medium

Exotic, invasive or introduced species or genome.

Threat Level of concerna Extent Occurrence Frequency Severityb Causal certaintyc
Invasive species Medium Local Current Continuous High/ Moderate Medium

Accidental mortality.

Threat Level of concern a Extent Occurrence Frequency Severityb Causal certaintyc
Collisions with cars and man-made structures Low Local Current Unknown Unknown Unknown

Disturbance or harm.

Threat Level of concerna Extent Occurrence Frequency Severityb Causal certaintyc
Recreational activities Low Local Current Recurrent Moderate Medium

Climate and natural disasters.

Threat Level of concerna Extent Occurrence Frequency Severityb Causal certaintyc
Climate change Low Widespread Anticipated Unknown Moderate/ Unknown Medium/ Low

Natural processes or activities.

Threat Level of concerna Extent Occurrence Frequency Severityb Causal certaintyc
Diseases Low Widespread Current Unknown High/ Low Low

aLevel of Concern: signifies that managing the threat is of (high, medium or low) concern for the recovery of the species, consistent with the population and distribution objectives. This criterion considers the assessment of all the information in the table.

bSeverity: reflects the population-level effect (High: very large population-level effect, Moderate, Low, Unknown).

cCausal certainty: reflects the degree of evidence that is known for the threat (High: available evidence strongly links the threat to stresses on population viability; Medium: there is a correlation between the threat and population viability e.g. expert opinion; Low: the threat is assumed or plausible).

dEach threat is evaluated at the local level (each site) and at the rangewide level. When two items are present in a box, this means that the threat level is not the same for both scales (Local scale / Rangewide scale).

4.2 Description of threats

Threats are listed in order of decreasing level of concern. However, apart from wetland destruction and degradation and impaired water quality, the level of concern is speculative because the prevalence and impact of threats are poorly documented in Canada. Some threats that occur on wintering grounds and along migration routes may have consequences on Least Bitterns that migrate to Canada for breeding. The absence of muskrats (who open corridors in the marsh vegetation) and the reduction of natural disturbances (e.g., fires that prevent shrubs from invading the habitat) are also limiting factors for the species.

Wetland destruction and degradation

Loss of wetland habitat as a result of human activities is thought to have severely reduced Least Bittern numbers across North America. The rate of large-scale wetland loss in southern Canada appears to have slowed in recent years, but wetlands continue to be drained for housing development and/or conversion to agricultural uses (Ducks Unlimited Canada, 2010). In Quebec, 80% of wetlands along the St. Lawrence River have been lost since European settlement (James, 1999; Painchaud and Villeneuve, 2003). Development up to the edge of marshes as well as fragmentation facilitates access to deeper portions of marshes by some mammalian predators footnote i , particularly raccoons (Jobin and Picman, 1997). Loss and degradation of wetlands is also an important factor in the United States (Dahl, 2006), affecting the migration and wintering habitats of the Canadian breeding population.

Impaired water quality

Run-off, siltation, acid rain and eutrophication can reduce prey abundance (Weller, 1999) and increase the likelihood of disease and toxicity. Any reduction in water clarity will also likely reduce the foraging success of a visual feeder such as the Least Bittern.

Single source pollution events such as toxic spills are particularly likely in marshes that border the busy shipping lanes of the St. Lawrence River and Great Lakes (Chapdelaine and Rail, 2004). The effects of such events on Least Bitterns have not been investigated but could be important since the species is known to bio-accumulate toxins in its eggs and feathers (Causey and Graves, 1969).

Regulated water levels

Since water-level management along the St. Lawrence River and Lake Ontario was established in the 1950s, the average maximum flow has decreased in summer and the average minimum flow has increased in winter (Morin and Leclerc, 1998). However, deviations from the regulation plan occur regularly and can impact the Least Bittern during crucial periods of reproduction (DesGranges et al., 2006). This situation may also be taking place in other important waterways such as the Ottawa River and even inland. Although Least Bitterns mostly occupy sites where water levels are stable during the breeding season, any dramatic change in water levels during this period is liable to affect the species negatively.

Prolonged periods of high water levels can reduce the extent of cattail marshes, both directly through flooding and indirectly by making conditions more favorable for other species such as Wild Rice (Zizania palustris) that are less suitable for nesting Least Bitterns (Sandilands and Campbell, 1988; Timmermans et al., 2008). Conversely, prolonged periods of relatively stable water levels may increase the density of cattail stands and eliminate open pools required by the species. Jobin et al. (2009) showed that the abundance of a Least Bittern population was reduced rapidly following a pronounced decrease of water depth due to a breach in an impounded wetland during the reproductive season followed by a rapid increase in abundance the following year when water depth returned to previous levels.

Invasive species

Several species of invasive plants and animals are increasing in range and abundance in North American marshes, largely due to human interventions. Purple Loosestrife (Lythrum salicaria), Reed Canary Grass (Phalaris arundinacea), European Common Reed (Phragmites autralis spp. australis), Flowering Rush (Butomus umbellatus) as well as a hybrid cattail (Typha x glauca) in the Great Lakes region are crowding out native emergent plants (Lavoie et al., 2003; Hudon, 2004; Jobin, 2006; Jobin et al., 2007; Latendresse and Jobin, 2007; Wilcox et al., 2007). While the Least Bittern can breed in a variety of emergent plants, including stands of invasive species, they preferentially breed in cattails (Poole et al., 2009). Floating invasive plants (e.g., European Frog-bit [Hydrocharis morsus-ranae] and Water Chestnut [Trapa natans]), can also alter habitat structure namely by accelerating marsh succession to drier conditions that are suboptimal for feeding and breeding (Blossey et al., 2001).

Populations of invasive animals such as Common Carp (Cyprinus carpio) are increasing in wetlands occupied by the Least Bittern, especially in southern Ontario and Quebec. In addition to their deleterious effects on ecosystem function, they may impact the Least Bittern more directly when stirring up sediments as they forage thereby reducing water clarity (Wires et al., 2010).

Collisions with cars and man-made structures

Least Bitterns fly at low levels and migrate at night, two characteristics which make them susceptible to collisions with vehicles, buildings, guy wires, power lines, barbed wire fences, and towers. These collisions may be frequent enough at some sites to threaten local populations (Poole et al., 2009). In one case, 12 Least Bitterns were killed in collisions with vehicles and four died after being impaled on a fence during one weekend on a road that passes through a refuge in Louisiana (Guillory, 1973). Least Bitterns have also been found dead along the Long Point (Ontario) causeway on a few occasions (Ashley and Robinson, 1996; J. McCracken personal communication). These incidents suggest that roads or structures built adjacent to suitable wetlands can cause mortality for birds moving between habitat patches or during migration.

Recreational activities

Although the Least Bittern can tolerate a certain level of human activity near wetlands used for breeding, including the occasional passage of small boats near their foraging areas (Poole et al., 2009), they seem to prefer nesting outside high density urban areas (Smith-Cartwright and Chow-Fraser, unpublished results). However, infrequent and unpredictable disturbance may be as disruptive to the Least Bittern as it is for other species that are intolerant of human activity (Nisbet, 2000). Frequent use of call broadcasts by recreational birders in wetlands where birding pressure is intense may also be disruptive to breeding Least Bitterns although the importance of this threat has not been evaluated. Finally, direct impacts such as waves from motorized watercrafts can erode wetland edges and possibly flood or upset nests.

Climate change

Climate change has the potential of having unpredictable, widespread and severe effects on the Least Bittern and its habitat. Climate change could increase the frequency of events such as floods and storms that can destroy nests and habitat, and may also change the overall hydrological and temperature regimes that account for the Least Bitterns' distribution in Canada. For example, the reduction of water levels caused by elevated temperatures will likely reduce the area of wetlands, and lead to reduced prey abundance (Mortsch et al., 2007; Wires et al., 2010). Alternatively, a potential northward expansion by the species could favor the use of numerous wetlands in the boreal forest although the quality of these habitats for breeding purposes would have to be assessed.

Diseases

The impact of various diseases and parasitism have been poorly studied in Least Bittern populations. Presumably, individuals are susceptible to diseases known to affect other wading birds (Friend and Franson, 1999; Wires et al., 2010). The Least Bittern is also one of 326 bird species in which West Nile Virus has been found (Center for Disease Control, 2009).

5. Population and distribution objectives

The population and distribution objectives for the Least Bittern are to maintain and, where possible, increase the current population size and area of occupancy in Canada. These objectives are considered possible in many parts of the range where adequate, yet currently unoccupied, breeding, foraging, post-breeding dispersal, moulting and migration stopover habitat is available or could be restored. Part of these objectives can only be achieved over the long term (>10 years).

The species' historical abundance and distribution are not well known, and specific habitat needs for different life stages and locations across its Canadian range are not understood well enough at present to set quantitative objectives. This may become possible in subsequent iterations of this recovery strategy as knowledge gaps are filled.

6. Broad strategies and general approaches to meet objectives

6.1 Actions already completed or underway

The following activities have been undertaken or completed in Canada since 2000:

  • Literature reviews of all available information on the Least Bittern (McConnell, 2004; Gray Owl Environmental Inc., 2009);
  • National Least Bittern survey protocol for the breeding season (Jobin et al., 2011 a,b);
  • National protocol for capturing, banding, radio-tagging and tissue sampling Least Bitterns in Canada (MacKenzie and McCracken, 2011);
  • Surveys of potential and historical sites have been conducted in southern Manitoba (2003-2008; R. Bazin pers. comm.; Hay, 2006), in Ontario (2001-2012; Bowles, 2002; Desy, 2007; Meyer and Friis, 2008) and in Quebec (2004-2013; Jobin, 2006; Jobin et al., 2007; Latendresse and Jobin, 2007; Jobin and Giguère, 2009);
  • Directed surveys in National Wildlife Areas in Ontario and Quebec;
  • Masters and PhD theses completed on Least Bittern breeding habitat in Ontario (N. Bartok - University of Western Ontario; P. Quesnelle - Carleton University; D. Tozer – Trent University) and Manitoba (S. Hay - University of Manitoba);
  • On-going monitoring programs: Great Lakes Coastal Wetland Monitoring Program (Canadian Wildlife Service-Ontario Region; Meyer et al., 2006); Marsh Monitoring Program in Ontario since 1994 and in Quebec since 2004; Monitoring of Least Bittern presence in several wetlands in southern Quebec as part of the avian species at risk annual breeding sites monitoring (SOS-POP); Prairies and Parkland pilot Marsh Monitoring Program since 2008;
  • Creation of the Samuel-de-Champlain biodiversity reserve (Natural heritage conservation Act of Quebec; R.S.Q. c. C-61.01) which will preserve 487 ha of wetlands on the shores of the Richelieu River near the Quebec/USA border. This will include two of the Least Bittern critical habitat units (Baie McGillivray and Rivière Richelieu-Frontière);
  • Broad efforts to protect, manage, and restore wetlands in Ontario are ongoing, for example, through the Eastern Habitat Joint Venture of the North American Waterfowl Management Plan and the Great Lakes Sustainability Fund;
  • The Walpole Island First Nation is developing an ecosystem protection plan based on the community’s traditional ecological knowledge.

6.2 Strategic direction for recovery

Table 4. Recovery planning for the Least Bittern.

Threats or limiting factor Broad strategy to recovery Priority General description of research and management approaches
All Stewardship and management of the species and its suitable habitat High
  • Apply stewardship measures and management tools (including legal protection) within the suitable habitat as well as in adjacent habitats in order to reduce the impact of various threats
  • Maintain or implement management approaches aiming at stabilizing or increasing the population size and the area of occupancy
Knowledge gaps Surveys and monitoring High
  • Develop a national monitoring strategy that includes:
    1. Least Bittern surveys within critical habitat, in habitats with known occupancy but that are not yet identified as critical habitat, as well as in habitats that are potentially suitable for all life stages in Canada
    2. Standardized techniques to determine population density, size and trend
    3. Standardized techniques to study dispersal and migration routes
    4. Monitoring wetland habitat characteristics as well as adjacent habitats
Wetland destruction; Impaired water quality; Regulated water levels; Knowledge gaps Research High
  • Determine key habitat attributes for all life cycle stages in Canada and how they vary spatially and temporally
All Communication and Partnerships Medium
  • Develop and implement a communication strategy with partner organizations, special interest groups, landowners and the general public

7. Critical habitat

7.1 Identification of the species' critical habitat

Critical habitat is partially identified for the Least Bittern in this recovery strategy. As there is limited information concerning most foraging, moulting, post-breeding dispersal and migration stopover habitats, critical habitat is only identified for the breeding habitat. A schedule of studies (section 7.2) is proposed to complete the identification of critical habitat.

The identification of critical habitat is based on two aspects: habitat suitability and habitat occupancy.

7.1.1 Habitat suitability

Habitat suitability refers to the attributes of habitats in which individuals may carry out breeding activities (e.g., courtship, territory defense, nesting). The biophysical attributes of suitable Least Bittern breeding habitat include:

  • permanent wetlands footnote ii (marshes and shrubby swamps within the boundaries of the high-water mark), And
  • tall and robust emergent herbaceous and/or woody vegetation interspersed with areas of open water (hemi-marsh conditions), And
  • Water level fluctuations close to those of a natural regime

Based on knowledge related to the average maximum movements during the breeding season (~400 m according to Bogner and Baldassarre, 2002b; 2,000 m according to Griffin et al., 2009), the suitable habitat within a 500 m radius was selected as representative of the area used by a Least Bittern individual or pair.

7.1.2 Habitat occupancy

Habitat occupancy relates to areas of suitable habitat that have documented use for breeding purposes in one or multiple years. Confirmed breeding records (see Appendix A for definitions) constitute the highest indication of habitat occupancy and therefore of the presence of suitable habitat. However, since confirming breeding is difficult for this secretive species (Tozer et al., 2007), records of multiple probable breeders in a single year or probable breeders in multiple years can also be used as indicators of habitat suitability, in particular as a demonstration of fidelity to specific wetlands. The remaining records of breeding activities (e.g., possible breeders) were not considered as sufficient indicators of the suitability of the habitat for reproduction since the Least Bittern may use some wetlands sporadically (e.g., for movements) or for non-reproductive purposes.

Given that wetland habitats are dynamic throughout the Canadian range, recent information may be more reliable for evaluating suitable habitat and Least Bittern occupancy. In light of this, the selection of records dating back a maximum of 10 years from when the recovery strategy was being prepared (i.e. starting in 2001) has been identified as appropriate. Furthermore, 2001 was the first year of data collection for the second Ontario Breeding Bird Atlas, which enabled confirmation of the continued use of individual wetlands (fidelity) at the heart of the species' range in Canada. Records older than 2001 will need to be validated to determine the continued presence of suitable habitat and current occupancy by the Least Bittern (see section 7.2).

7.1.3 Critical habitat identification for the Least Bittern

Critical habitat is identified in this recovery strategy as the suitable habitat within 500 m of coordinates corresponding to the following minimum breeding activity:

  • one record of confirmed breeding since 2001; Or
  • two records of probable breeding in any single year since 2001; Or
  • one record of probable breeding in each of two separate years within a 5-year floating window footnote iii since 2001

Depending on its area, structure and the nature of observed reproductive activities, a wetland can be identified as a single critical habitat unit or can include multiple units. Overlapping units are merged together to form a single larger unit.

Using these criteria, 115 critical habitat units containing up to 17 102 ha of Least Bittern critical habitat have been identified (see Appendix B), including 10 in Manitoba (1,856 ha), 54 in Ontario (10,740 ha), 48 in Quebec (4,615 ha) and 3 in New Brunswick (137 ha). Within a critical habitat unit, any man-made structure (e.g., roads, wharves, powerline poles) or areas (e.g., ploughed agricultural land, deep open water) that do not possess the biophysical attributes of suitable habitat are not identified as critical habitat.

7.1.4 Non-critical habitats

The Least Bittern may occasionally nest in non-traditional habitats (e.g., roadside ditches, sewage lagoons) that are anthropogenic in nature and not managed for conservation purposes. These habitats do not provide sustained, high quality breeding conditions given that they may be the object of frequent interventions that could negatively affect breeding individuals. Consequently, they are not identified as critical habitat under SARA, even if breeding is confirmed. However, the general prohibitions under SARA and the Migratory Birds Convention Act, 1994 (S.C., 1994, c. 22) protecting the birds and their residences (nests) from damage or destruction remain in effect.

7.2 Schedule of studies to identify critical habitat

Table 5. Schedule of studies.

Description of activity Rationale Timeline
Conduct surveys in wetlands where:
  • Breeding has been confirmed between 1991-2000a;
  • Least Bitterns are present but the criteria to identify critical habitat have not been met since 1991;
  • There is suitable habitat, but no standardized surveys have been conducted since 1991.
Additional critical habitat units identified, particularly in more remote areas 2014-2019
Characterize foraging, post-breeding dispersal, moulting and migration stopover habitats in Canada and survey Least Bitterns within them in the appropriate periods of the year Additional critical habitat units identified; Needed to conserve the species in throughout its life cycle in Canada 2014-2019

aThe 1991 year has been selected based on the fact that Conservation Data Centres consider records older than 20 years to be historical.

7.3 Activities likely to result in the destruction of critical habitat

Destruction is determined on a case by case basis. Destruction would result if part of the critical habitat was degraded, either permanently or temporarily, such that it would not serve its function when needed by the species (Government of Canada, 2009). Destruction may result from a single activity or multiple activities at one point in time or from the cumulative effects of one or more activities over time. Examples of activities likely to result in the destruction of critical habitat for the Least Bittern are shown in Table 6.

Table 6. Examples of activities likely to destroy Least Bittern critical habitat.

Description of the activity a Description of the effect (biophysical attributes or other) Scale of activity likely to destroy critical habitat b Site Scale of activity likely to destroy critical habitatbArea Scale of activity likely to destroy critical habitatbLandscape Timing considerations
Infilling, excavation or draining of wetlands (e.g., infrastructure development and construction, superficial mineral extraction; underground mineral/hydrocarbon extraction, dredging and channelization)
  • Direct loss of wetland habitats;
  • Changes to the hydrological regime (e.g., water levels);
  • Creation of unsuitable conditions for the growth of wetland vegetation;
  • Introduction of exotic or invasive species
X X - Applicable at all times
Activities that generate soil run-off and increased water turbidity or nutrient influx (e.g., cultivating the land next to a wetland without proper vegetation buffers)
  • Proliferation of vegetation associated with eutrophication (floating or emergent);
  • Habitat alteration (e.g., increased turbidity reduces foraging success)
X X - Applicable at all times
Introduction of invasive vegetation, fish and invertebrate species
  • Habitat alteration (e.g., increased turbidity or changes in prey availability reduces foraging success);
  • Changes to the conditions for nest building (e.g., structure and/or composition of the vegetation)
X - - Applicable at all times
Repeated use of vehicles and motor boats within or close to wetlands
  • Habitat degradation (via erosion)
  • Generation of waves that can flood nests (reduced suitable breeding habitat)
X - - Applicable at all times in relation to erosion ; Applicable during the breeding period in relation to the flooding of nest component
Prescribed burns or other means of natural vegetation removal within wetland habitats
  • Removal of elements that are used for nest construction or other activities (e.g., foraging)
X - - Can be conducted when individuals have left the habitat (after the fall migration)
Deposition of deleterious substances (including snow), either directly (in water) or indirectly (upstream, soil)
  • Reduced water quality (e.g., turbidity, pollution) decreases prey availability and foraging success;
  • Bioaccumulation of toxic substances in feathers and eggs
X X - Applicable at all times
Construction of infrastructures (e.g., roads, houses, boat ramps) which increase the access to critical habitat
  • Disturbance of breeding activities by an increased use of wetlands (reduced suitable breeding habitat);
  • Can increase predation by facilitating access to nests;
  • Increased occurrence of other threats (e.g., collisions)
X X - Applicable at all times
Presence of livestock that removes or tramples the vegetation
  • Destruction of emergent aquatic vegetation (directly and via erosion and soil compaction)
X - - Applicable at all times

aActivities required to manage, inspect and maintain existing infrastructures that are not critical habitat but whose footprints may be within or adjacent to critical habitat units are not examples of activities likely to result in the destruction of critical habitat provided that they are carried out in a manner consistent with Least Bittern critical habitat conservation. Furthermore, management of wetlands for wildlife conservation purposes does not typically result in destruction of critical habitat if activities take place when the individuals are not present in the habitat (after migration). For additional information, communicate with Environment Canada – Canadian Wildlife Service at : enviroinfo@ec.gc.ca.

bSite: anticipated effect close to 1 x 1 km; Area: 10 x 10 km; Landscape: 100 x 100 km.

8. Measuring progress

The performance indicators presented below provide a way to define and measure progress toward achieving the population and distribution objectives.

  • the population size of Least Bittern is maintained and, where possible, increased;
  • the area of occupancy is maintained and, where possible, increased.

9. Statement on action plans

One or more action plans associated with the recovery strategy will be elaborated in the coming years. They will be posted on the Species at Risk Public Registry by 2019.

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Jobin, B., C. Latendresse et L. Robillard. 2007. Habitats et inventaires du Petit Blongios sur les terres du ministère de la Défense nationale à Nicolet, Quebec, étés 2004, 2005 et 2006. Série de rapports techniques no 482, Service canadien de la faune, région du Quebec, Environnement Canada, Sainte-Foy, Quebec, 85 pp. et annexes.

Jobin, B., L. Robillard and C. Latendresse. 2009. Response of a Least Bittern (Ixobrychus exilis) population to interannual water level fluctuations. Waterbirds 32: 73-80.

Jobin, B., M.J. Mazerolle, N.D. Bartok and Bazin, R. 2013. Least Bittern occupancy dynamics and detectability in Manitoba, Ontario and Québec. Wilson Journal of Ornithology 125: 62-69.

Jobin, B., R. Bazin, L. Maynard, A. McConnell and J. Stewart. 2011a. National Least Bittern Survey Protocol. Technical Report Series No. 519, Environment Canada, Canadian Wildlife Service, Quebec Region, Quebec. 26 pp.

Jobin, B., R. Bazin, L. Maynard, A. McConnell and J. Stewart. 2011b. Least Bittern (Ixobrychus exilis) survey protocol. Waterbirds 34: 225-233.

Johnson, D.J., J.P. Gibbs, M. Herzog, S. Lor, N.D. Niemuth, C.A. Ribic, M. Seamans, T.L. Schaffer, G. Shriver, S. Stehman, and W.L. Thompson. 2009. A sampling design framework for monitoring secretive marshbirds. Waterbirds 32: 203-215.

Kushlan, J. A. 1973. Least Bittern nesting colonially. Auk 90: 685-686.

Kushlan, J.A., and J.A. Hancock. 2005. Herons. Oxford University Press, Oxford.

Latendresse, C., and B. Jobin. 2007. Inventaire du Petit Blongios à la baie McLaurin et au marais aux Massettes, région de l'Outaouais, été 2006. Environnement Canada, Service canadien de la faune, région du Quebec, Sainte-Foy. Rapport inédit. 40 p. et annexes.

Lavoie, C., M. Jean, F. Delisle, and G. Létourneau. 2003. Exotic plant species of the St.Lawrence River wetlands: a spatial and historical analysis. Journal of Biogeography 30: 537-49.

Mackenzie, S.A., and J.D. McCracken. 2011. National protocol for capturing, banding, radio-tagging and tissue sampling Least Bitterns in Canada. Prepared for Environment Canada, Canadian Wildlife Service and the National Least Bittern Recovery Team. Bird Studies Canada, 30 pp.

McConnell, A. 2004. Draft Least Bittern Background Report, Version 1.0. Prepared for the Canadian Wildlife Service, Environment Canada, Ontario Region.

McKercher, R.B., and B. Wolf. 1986. Understanding Western Canada’s Dominion Land Survey System. Saskatoon: Division of Extension and Community Relations, University of Saskatchewan.

Meyer, S.W. and C.A. Friis. 2008. Occurrence and habitat of breeding Least Bitterns at St. Clair National Wildlife Area. Ontario Birds 26: 146-164.

Meyer, S.W., J.W. Ingram, and G.P. Grabas. 2006. The Marsh Monitoring Program: Evaluating marsh bird survey protocol modifications to assess Lake Ontario coastal wetlands at a site-level. Technical Report Series 465. Canadian Wildlife Service, Ontario region, Ontario.

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Yocum, B.J. 2007. Breeding biology of and nest site selection by Least Bitterns (Ixobrychus exilis) near Saginaw Bay, Michigan. M.Sc. thesis, Central Michigan University, Mount Pleasant, Michigan, USA.

Appendix A: Standard Breeding Bird Atlas codes

Breeding designation Atlas codea and description
Probable breeding P: Pair observed in their breeding season in suitable nesting habitat
T: Permanent territory presumed through registration of territorial behaviour (song, etc.), or the occurrence of an adult bird, on at least two days, a week or more apart, at the same place, in suitable nesting habitat during the breeding season
D: Courtship or display between a male and a female or two males including courtship, feeding or copulation
V: Visiting probable nest site
A: Agitated behaviour or anxiety calls of an adult indicating nest-site or young in the vicinity
B: Brood patch on adult female or cloacal protuberance on adult male
Confirmed breeding NB: Nest building or carrying nest materials
DD: Distraction display or injury feigning
NU: Used nest or egg shells found (occupied or laid within the period of the survey). Use only for unique and unmistakable nests or shells
FY: Recently fledged young or downy young
AE: Adults leaving or entering nest sites in circumstances indicating occupied nest (including nests which content cannot be seen)
FS: Adult carrying fecal sac
CF: Adult carrying food for young during its breeding season
NE: Nest containing eggs
NY: Nest containing young seen or heard

aAtlas codes and descriptions can vary slightly from one province to another but convey similar meanings. Atlas codes for possible breeding are not presented here.

Appendix B: Critical habitat for the Least Bittern in Canada

Table B-1. Description of the 10 x 10 km Standardized UTM Grid, Quarter Sections and Critical Habitat Units for the Least Bittern in Manitoba.

Name of the critical habitat unit 10 x 10 km UTM grid ID a UTM grid coordinates b Easting UTM grid coordinatesbNorthing Quarter sectionsccontaining critical habitat Quarter sectionsc containing critical habitat Critical habitat unit area (ha)d Description Land tenuree
Brokenhead Swamp 14PA82 680000 5520000 NE-12-10-08-E1
NW-07-10-09-E1
NW-18-10-09-E1
SW-18-10-09-E1
SE-13-10-08-E1
NE-13-10-08-E1
111 Located in a freshwater wetland east of PR302, north of Hwy 1 and south of Hwy 15 near the town of Ross Non federal
Buffalo Lake 14NB92 590000 5620000 NW-10-21-02-W1
NE-10-21-02-W1
SE-15-21-02-W1
NE-15-21-02-W1
SW-15-21-02-W1
NW-14-21-02-W1
SW-14-21-02-W1
NW-11-21-02-W1
241 Located in a freshwater wetland north of PR419, east of PR512 and north of Hwy 17 near the town of Chatfield Non federal
Fish Lake 14PB12 610000 5620000 SW-30-20-02-E1
NW-30-20-02-E1
SE-25-20-01-E1
NE-25-20-01-E1
131 Located in a freshwater wetland east of Hwy 17 and west of Hwy 7 near the town of Meleb Non federal
Little Birch Lake West 14NB66 560000 5660000 SW-11-25-05-W1
SE-11-25-05-W1
NW-11-25-05-W1
NE-11-25-05-W1
SE-14-25-05-W1
SW-14-25-05-W1
104 Located in a freshwater wetland south of PR325 and north of Sleeve Lake near the town of Ashern Non federal
Little Birch Lake East 14NB66 560000 5660000 SE-12-25-05-W1
SW-12-25-05-W1
NE-01-25-05-W1
NW-01-25-05-W1
79 Located in a freshwater wetland south of PR325 and north of Sleeve Lake near the town of Ashern Non federal
Rat River Swamp West 14PV65 660000 5450000 NW-20-03-06-E1
SE-29-03-06-E1
NE-29-03-06-E1
NE-20-03-06-E1
SE-21-03-06-E1
SW-20-03-06-E1
NW-16-03-06-E1
SE-20-03-06-E1
NE-21-03-06-E1
NW-21-03-06-E1
NE-17-03-06-E1
NW-17-03-06-E1
SW-27-03-06-E1
SE-19-03-06-E1
NW-27-03-06-E1
SW-28-03-06-E1
NW-28-03-06-E1
SE-28-03-06-E1
NE-28-03-06-E1
NE-18-03-06-E1
693 Located in a freshwater wetland east of Hwy 59, west of PR302 and north of the Vita Drain along the Rat River near the towns of Rosa and Zhoda Non federal
Rat River Swamp Centre 14PV65 660000 5450000 NW-26-03-06-E1 NE-27-03-06-E1 NE-34-03-06-E1 SE-34-03-06-E1
NW-35-03-06-E1
SW-35-03-06-E1
125 Located in a freshwater wetland east of Hwy 59, west of PR302 and north of the Vita Drain along the Rat River near the towns of Rosa and Zhoda Non federal
Rat River Swamp East 14PV75 14PV76 670000 670000 5450000
5460000
NW-34-03-07-E1
NE-33-03-07-E1
NW-33-03-07-E1
SW-04-04-07-E1 SE-04-04-07-E1 SW-03-04-07-E1 190 Located in a freshwater wetland east of Hwy 59, west of PR302 and north of the Vita Drain along the Rat River near the towns of Rosa and Zhoda Non federal
Sleeve Lake 14NB66 560000 5660000 NW-19-24-04-W1 NE-19-24-04-W1 SE-30-24-04-W1
SW-30-24-04-W1
79 Located in a freshwater wetland south of PR325 and south of Little Birch Lake near the town of Ashern Non federal
Unnamed Lake (locally called Little Sleeve Lake) 14NB66 560000 5660000 NE-36-24-05-W1
SE-01-25-05-W1
SE-06-25-04-W1
NW-31-24-04-W1
SW-06-25-04-W1
103 Located in a freshwater wetland south of PR325 between Little Birch Lake and Sleeve Lake near the town of Ashern Non federal
Totals N/A N/A N/A N/A N/A Total 1,856 ha in 10 critical habitat units N/A N/A

aGrid ID is based on the standard Universal Transverse Mercator (UTM) Military Grid Reference System, where the first two digits represent the UTM Zone, the following two letters indicate the 100 x 100 km standardized UTM grid, followed by two digits to represent the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. This unique alphanumeric code is based on the methodology produced from the Breeding Bird Atlases of Canada (See Bird Studies Canada’s website for more information on breeding bird atlases).

bThe listed coordinates represent the southwest corner of the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. The coordinates may not fall within critical habitat and are provided as a general location only.

cQuarter section descriptions are based on the Dominion Land Survey System, whereby most of western Canada is legally divided into townships based on longitudinal meridians and latitudinal base lines. Each township is given a township number and range number. Townships are approximately 9.7 x 9.7 km (6 x 6 mi) and are further divided into thirty-six sections, each about 1.6 x 1.6 km (1 x 1 mi). In turn, each section is divided into four quarter sections: southeast, southwest, northwest and northeast, which are 0.8 x 0.8 km (0.5 x 0.5 mi). For example, the full legal description of quarter section NW-36-002-06-E is the Northwest Quarter of Section 36, Township 002, Range 06, east of the First Meridian (see McKercher and Wolf, 1986 for more information).

dThe area presented is that of the critical habitat unit boundary (rounded up to the nearest 1 ha); an approximation based on a maximum extent that may contain critical habitat. The actual area of critical habitat may be much less depending on where the criteria for critical habitat are met. Refer to section 7.1 for a description of how critical habitat within these areas is defined. Field verification may be required to determine the precise area of critical habitat.

eLand Tenure is provided as an approximation of land ownership of the critical habitat unit and should be used for guidance purposes only. Accurate land tenure will require cross referencing critical habitat boundaries with surveyed land unit information.

Table B-2. Description of the 10 x 10 km Standardized UTM Grid and Critical Habitat Units for the Least Bittern in Ontario.

Name of the critical habitat unit 10 x 10 km UTM grid ID a UTM grid coordinates b Easting UTM grid coordinatesbNorthing Critical habitat unit area (ha)c Description Land tenured
Rainy Lake 15VP99 490000 5390000 104 Rainy Lake, District of Rainy River Non federal
Lighthouse Point Provincial Nature Reserve 17LG63 360000 4630000 84 Lighthouse Point Provincial Park, Essex County Non federal
Hillman Marsh Conservation Area 17LG75 370000 4650000 154 Hillman Marsh Conservation Area, Essex County Non federal
Wheatley East Two Creeks 17LG85
17LG86
380000
380000
4650000
4660000
84 Wheatley Provincial Park, Municipality of Chatham-Kent Non federal
St. Clair NWA Marsh Complex - St. Clair Unit 17LG89 380000 4690000 712 St. Clair NWA - St. Clair Unit, Municipality of Chatham-Kent Federal and Non federal
St. Clair Marsh Complex 17LH80 380000 4700000 155 Middle section St. Clair Marsh, Municipality of Chatham-Kent Non federal
Mitchell’s Bay, Lake St. Clair 17LH80 380000 4700000 141 Mitchell’s Bay, Lake St. Clair, Municipality of Chatham-Kent Non federal
St. Clair NWA Marsh Complex - Bear Creek Unit 17LH80
17LH81
380000
380000
4700000
4710000
300 St. Clair NWA - Bear Creek Unit, Municipality of Chatham-Kent Federal and Non federal
Rondeau Provincial Park 1 17MG28 420000 4680000 165 West side of Rondeau Provincial Park, Municipality of Chatham-Kent Non federal
Rondeau Provincial Park 2 17MG28
17MG38
420000
430000
4680000
4680000
83 Rondeau Provincial Park, Municipality of Chatham-Kent Non federal
Hullett Marsh Complex 17MJ63 460000 4830000 82 East of Clinton, Huron County Non federal
Rankin River Wetland 17MK76
17MK86
470000
480000
4960000
4960000
92 South of Sky Lake Management Area, Bruce County Non federal
Big Creek NWA, Crown Marsh, Long Point Provincial Park 17NH41
17NH51
540000
550000
4710000
4710000
1281 West end of Long Point Sandspit, Norfolk County Federal and Non federal
Unnamed Wetland - Haldimand-Norfolk County 17NH41 540000 4710000 83 Wetland east of Long Point Road, Norfolk County and portion of wetland in Big Creek NWA -Big Creek Unit Federal and Non federal
Little Rice Bay Marsh - Thoroughfare Unit, Long Point NWA 17NH51 550000 4710000 141 Little Rice Bay Marsh area of Thoroughfare Unit, Norfolk County Federal and Non federal
Big Rice Bay Marsh - Thoroughfare Unit, Long Point NWA 17NH51 550000 4710000 418 Big Rice Bay Marsh area of Thoroughfare Unit, Norfolk County Federal and Non federal
Long Point Provincial Park 17NH51 550000 4710000 119 Wetland in Long Point Provincial Park, Norfolk County with portion extending into Long Point NWA-Thoroughfare Unit Federal and Non federal
Indian Creek Wetland 17NH52 550000 4720000 1234 West of Turkey Point, Norfolk County Non federal
Long Point Unit - Long Point NWA 17NH61
17NH71
560000
570000
4710000
4710000
1068 Along north shoreline of Long Point Unit, Norfolk County Federal
Luther Marsh 17NJ46 540000 4860000 82 East part of Luther Marsh Conservation Area, Wellington County Non federal
Arkell - Corwhin Wetland Complex 17NJ62
17NJ72
560000
570000
4820000
4820000
82 South of Eden Mills, Regional Municipality of Halton Non federal
Tiny Marsh (Ti7) 17NK83 580000 4930000 310 Northeast of Allenwood, Simcoe County Non federal
Wye Marsh (TA2) 17NK84
17NK85
17NK95
580000
580000
590000
4940000
4950000
4950000
323 Southwest section of Wye Marsh, Simcoe County Non federal
Sturgeon Bay Marsh 17NK95
17PK05
590000
600000
4950000
4950000
104 Southwest end of the Trent Severn Waterway, Simcoe County Federal and Non federal
Cache Bay Wetland 17NM73 570000 5130000 123 Cache Bay Wetland, District Municipality of Nipissing Non federal
Beaverton River Wetland Complex 17PJ59 650000 4890000 82 Beaverton River Wetland Complex, Regional Municipality of Durham Non federal
Matchedash Bay Wetland (SE11) 17PK05 600000 4950000 115 North end of Matchedash Bay Wetland, Simcoe County Non federal
Wenona Marsh 17PK26 620000 4960000 81 South of Gravenhurst, District Municipality of Muskoka Non federal
Sturgeon Lake No. 26 17PK71
17PK72
670000
670000
4910000
4920000
190 North of Lindsay, City of Kawartha Lakes Federal and Non federal
Miller Creek Wildlife Area 17QK11 710000 4910000 82 Miller Creek Wildlife Area, County of Peterborough Non federal
Snelgrove Brook 17QK11
17QK12
710000
710000
4910000
4920000
82 East of Bridgenorth, County of Peterborough Non federal
Woodview Swamp 17QK21 720000 4910000 82 West of Jermyn, County of Peterborough Non federal
Birdsalls Creek 17QK30 730000 4900000 82 South of Westwood, County of Peterborough Non federal
Presqu'ile Bay Marsh 1 18TP87 270000 4870000 329 Middle section of Presqu'ile Provincial Park, Northumberland County Non federal
Presqu'ile Bay Marsh 2 18TP77
18TP87
270000
280000
4870000
4870000
138 North end of Presqu'ile Provincial Park, Northumberland County Non federal
Presqu'ile Bay Marsh 3 18TP87 280000 4870000 189 Presqu'ile Bay Marshes, Northumberland County Non federal
Unnamed Wetland - City of Quinte West 18TP99 290000 4890000 92 Northeast of Johnstown, City of Quinte West Non federal
Hoards Creek 18TQ80 280000 4900000 82 South of Hoards, Northumberland County Federal and Non federal
Sawguin Creek Marsh 18UP18 310000 4880000 125 North of Ameliasburg, City of Prince Edward County Non federal
Sandbanks Provincial Park 18UP26 320000 4860000 82 Southeast section of Sandbank Provincial Park, City of Prince Edward County Non federal
Marysville Creek Wetland 18UP29 320000 4890000 131 East of Big Bay, Tyendinaga Mohawk Territory Federal
Unnamed Wetland 1 - City of Prince Edward County 18UP35
18UP36
330000
330000
4850000
4860000
101 East of Point Petre Militaries Reserves Site, City of Prince Edward County Non federal
Unnamed Wetland 2 - City of Prince Edward County 18UP39 330000 4890000 82 North of Solmesville, City of Prince Edward County Non federal
Big Sand Bay 18UP46 340000 4860000 146 West of Prince Edward Point National Wildlife Area, City of Prince Edward County Non federal
Ross Lake Wetland 18UQ01 300000 4910000 103 North of Madoc Junction, Hastings County Non federal
Parks Creek 18UQ10 310000 4900000 82 South of Halston, Hastings County Non federal
Thrashers Corners Wetland 18UQ10 310000 4900000 119 Northeast of Thurlow, City of Belleville Non federal
Hutton Creek Wetland 18VQ15
18VQ16
410000
410000
4950000
4960000
81 West of Motts Mills, United Counties of Leeds and Grenville Non federal
The Swale Wetland 18VQ17 410000 4970000 81 West of Smiths Falls, Lanark County Federal and Non federal
Mud Creek 18VQ35 430000 4950000 138 West of North Augusta, United Counties of Stormont, Dundas and Glengarry Non federal
Upper Canada Migratory Bird Sanctuary 18VQ97 490000 4970000 81 Upper Canada Migratory Bird Sanctuary, United Counties of Stormont, Dundas and Glengarry Non federal
Mississippi River Snye 18VR03 400000 5030000 81 South of Fitzroy Harbour, City of Ottawa Non federal
Cooper Marsh 18WQ39 530000 4990000 81 West of South Lancaster, United Counties of Stormont, Dundas and Glengarry Non federal
Loch Garry 18WR21 520000 5010000 81 South of Greenfield, United Counties of Stormont, Dundas and Glengarry Non federal
Totals N/A N/A N/A Total 10,745 ha in 54 critical habitat units N/A N/A

aGrid ID is based on the standard Universal Transverse Mercator (UTM) Military Grid Reference System, where the first two digits represent the UTM Zone, the following two letters indicate the 100 x 100 km standardized UTM grid, followed by two digits to represent the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. This unique alphanumeric code is based on the methodology produced from the Breeding Bird Atlases of Canada (See Bird Studies Canada’s website for more information on breeding bird atlases).

b The listed coordinates represent the southwest corner of the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. The coordinates may not fall within critical habitat and are provided as a general location only.

cThe area presented is that of the critical habitat unit boundary (rounded up to the nearest 1 ha); an approximation based on a maximum extent that may contain critical habitat. The actual area of critical habitat may be much less depending on where the criteria for critical habitat are met. Refer to section 7.1 for a description of how critical habitat within these areas is defined. Field verification may be required to determine the precise area of critical habitat.

dLand Tenure is provided as an approximation of land ownership of the critical habitat unit and should be used for guidance purposes only. Accurate land tenure will require cross referencing critical habitat boundaries with surveyed land unit information.

Table B-3. Description of the 10 x 10 km Standardized UTM Grid and Critical Habitat Units for the Least Bittern in Quebec.

Name of the critical habitat unit 10 x 10 km UTM grid ID a UTM grid coordinates b Easting UTM grid coordinatesbNorthing Critical habitat unit area (ha)c Description Land tenured
Marais du Chemin du Lac Curley 18VR05 400000 5050000 79 North of the city of Gatineau; within Gatineau Park Federal
Lac La Pêche 18VR05 400000 5050000 12 North of the city of Gatineau; within Gatineau Park Federal
North Onslow (sud-ouest) 18VR05 400000 5050000 79 North of the city of Gatineau; within Gatineau Park Federal
Marais du Lac Brown 18VR25 420000 5050000 79 West of Highway 5, near Wakefield; within Gatineau Park Federal
Marais McLaurin Ouest 18VR53 450000 5030000 152 East of the city of Gatineau Non federal
Marais McLaurin Est 18VR53 450000 5030000 220 East of the city of Gatineau Non federal
Marais des Laîches 18VR53 450000 5030000 79 East of the city of Gatineau Non federal
Marais aux Grenouillettes 18VR53
18VR63
18VR64
450000
460000
460000
5030000
5030000
5040000
40 Managed wetland East of the city of Gatineau Non federal
Marais aux Massettes 18VR74 470000 5040000 99 Managed wetland East of the city of Gatineau Non federal
Marais aux rubaniers 18VR94 490000 5040000 79 South of the city of Plaisance Non federal
La Grande Baie (parc provincial d'Oka) 18WR73 570000 5030000 79 In Oka provincial Park Non federal
Parc-nature du Bois-de-l'île-Bizard 18WR84 580000 5040000 12 Regional park in Montreal Non federal
Grand marais de Beauharnois 18WR81 580000 5010000 102 Managed wetland in Beauharnois Non federal
Marais de Beauharnois N.-O. et S.-O. – Étang 1 18WR81 580000 5010000 79 Managed wetland in Beauharnois Non federal
Marais de Beauharnois N.-O. et S.-O. – Étang 2 18WR81 580000 5010000 159 Managed wetland in Beauharnois Non federal
Île Saint-Bernard 18WR92 590000 5020000 213 Managed wetland in Chateauguay Non federal
Ruisseau Saint-Jean 18WR92 590000 5020000 23 West of Chateauguay Non federal
Île des Sœurs 18XR13 610000 5030000 8 On Nun’s island in the city of Montréal Non federal
Marais du Bois 440 18XR05 600000 5050000 9 Wetland in the city of Laval Non federal
Île aux Fermiers 18XR25 620000 5050000 133 On an island East of Montréal Federal
Rivière aux Pins (La Frayère) 18XR25 620000 5050000 12 North of Boucherville Non federal
Rue Alfred (Saint-Amable) 18XR25
18XR35
620000
630000
5050000
5050000
158 At the end of Alfred street in Saint-Amable Non federal
Île Tourte Blanche 18XR15 610000 5050000 3 West of Parc national des Îles de Boucherville Federal
Pointe à la Meule 18XR30
18XR31
630000
630000
5000000
5010000
118 Along the Richelieu river; south of Saint-Jean-sur-Richelieu Non federal
Baie McGillivray 18XR30 630000 5000000 102 Along the Richelieu river; East of l'Île aux noix Non federal
Rivière du Sud - A 18XQ39 630000 4990000 328 East of the Richelieu River near the Quebec/USA border; Downstream portion of the river Non federal
Rivière du Sud - B 18XQ49 640000 4990000 130 East of the Richelieu River near the Quebec/USA border; Upstream portion of the river Non federal
Anse à l'Esturgeon 18XQ39 630000 4990000 118 Along the Richelieu river; south of l'Île aux noix Non federal
Rivière Richelieu (frontière) 18XQ28
18XQ38
620000
630000
4980000
4980000
94 Along the Richelieu river at the Quebec/USA border Non federal
Baie Missisquoi (rivière aux Brochets) 18XQ49
18XQ59
640000
650000
4990000
4990000
170 North of Lake Champlain Non federal
Ruisseau Black (La Swamp) 18XQ49 640000 4990000 122 North of Lake Champlain Non federal
Étang Streit (Refuge d'oiseaux migrateurs de Phillipsburg) 18XQ58 650000 4980000 79 Philipsburg Migratory Bird Sanctuary, east of Lake Champlain Non federal
Farnham (base militaire 7B) 18XR51
18XR52
650000
650000
5010000
5020000
10 North of Farnham Federal
Farnham (base militaire 6B) 18XR51 650000 5010000 17 North of Farnham Federal
Marais de l'Estriade 18XR82
18XR83
680000
680000
5020000
5030000
79 East of Granby Non federal
Marais de la rivière aux cerises 18YR21 720000 5010000 140 In Magog Non federal
Marais Réal-D. Carbonneau 19BL73 270000 5030000 11 Managed wetland in Sherbrooke Non federal
Île du Moine 18XS50 650000 5100000 122 Managed wetland on an island East Sorel-Tracy Federal / Non federal
Baie Lavallière 18XS50 650000 5100000 91 Northern portion of the wetland East of Sorel-Tracy Non federal
Île des Barques 18XS50 650000 5100000 51 Managed wetland on an island East of Sorel-Tracy Federal
Baie Saint-François 18XS50
18XS60
650000
660000
5100000
5100000
367 East of Sorel-Tracy Non federal
Rivière Saint-Joseph 18XR39 630000 5090000 143 Southwest of Berthierville Non federal
Saint-Barthélémy (bassin Ouest) 18XS51 650000 5110000 18 Managed wetland south of Saint-Barthélémy Non federal
Saint-Barthélémy (bassin Est) 18XS51 650000 5110000 27 Managed wetland south of Saint-Barthélémy Non federal
Marais de la Commune 18XS71 670000 5110000 31 Managed wetland East of Sorel-Tracy Non federal
Marais aménagés du refuge d'oiseaux migrateurs de Nicolet 18XS71 670000 5110000 317 Managed wetlands West of Nicolet within Nicolet Migratory Bird Sanctuary Federal / Non federal
Marais Provencher 19CM07 300000 5170000 19 Managed wetland in Neuville Non federal
Étang de la Grande Ferme (Réserve nationale de faune du cap Tourmente) 19CN61 360000 5210000 3 Managed wetland in Cap Tourmente National Wildlife Area Federal
Totals N/A N/A N/A Total of 4,615 ha in 48 critical habitat units N/A N/A

aGrid ID is based on the standard Universal Transverse Mercator (UTM) Military Grid Reference System, where the first two digits represent the UTM Zone, the following two letters indicate the 100 x 100 km standardized UTM grid, followed by two digits to represent the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. This unique alphanumeric code is based on the methodology produced from the Breeding Bird Atlases of Canada (See Bird Studies Canada’s website for more information on breeding bird atlases).

bThe listed coordinates represent the southwest corner of the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. The coordinates may not fall within critical habitat and are provided as a general location only.

cThe area presented is that of the critical habitat unit boundary (rounded up to the nearest 1 ha); an approximation based on a maximum extent that may contain critical habitat. The actual area of critical habitat may be much less depending on where the criteria for critical habitat are met. Refer to section 7.1 for a description of how critical habitat within these areas is defined. Field verification may be required to determine the precise area of critical habitat.

dLand Tenure is provided as an approximation of land ownership of the critical habitat unit and should be used for guidance purposes only. Accurate land tenure will require cross referencing critical habitat boundaries with surveyed land unit information.

Table B-4. Description of the 10 x 10 km Standardized UTM Grid, Atlas Blocks and Critical Habitat Units for the Least Bittern in New Brunswick.

Name of the critical habitat unit 10 x 10 km UTM grid ID a New Brunswick Atlas block reference b UTM grid coordinates c Easting UTM grid coordinatescNorthing Critical habitat unit area (ha)d Description Land tenuree
St. George’s Marsh 19FL70
19FK79
NB Atlas p. 90
square B3
670000
670000
5000000
4990000
38 The St. George marsh is located in St. George and borders the Trans Canada highway Non federal
Germantown Marsh (Shepody National Wildlife Area) 20LR66 NB Atlas p. 82
square C1
360000 5060000 20 The two northern most controlled water level impoundments (A and A-1) east of the Shepody River within the north east corner of the Germantown Marsh unit (NB Atlas p. 82, Square C1) within the Shepody National Wildlife Area Federal
Bell Marsh 20LS50 NB Atlas p. 65 squares B4, B5 350000 5100000 79 The Bell Marsh borders the north shore of the Petitcodiac river and is situated south of Marsh Junction near Moncton Non federal
Totals N/A N/A N/A N/A Total of 137 ha in 3 critical habitat units N/A N/A

aGrid ID is based on the standard Universal Transverse Mercator (UTM) Military Grid Reference System, where the first two digits represent the UTM Zone, the following two letters indicate the 100 x 100 km standardized UTM grid, followed by two digits to represent the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. This unique alphanumeric code is based on the methodology produced from the Breeding Bird Atlases of Canada (See Bird Studies Canada’s website for more information on breeding bird atlases).

bReference number consists of the page number and block(s) where the critical habitat is located as identified in the 2002 edition of the New Brunswick Atlas (Province of New Brunswick, 2002).

cThe listed coordinates represent the southwest corner of the 10 x 10 km standardized UTM grid containing all or a portion of the critical habitat unit. The coordinates may not fall within critical habitat and are provided as a general location only.

dThe area presented is that of the critical habitat unit boundary (rounded up to the nearest 1 ha); an approximation based on a maximum extent that may contain critical habitat. The actual area of critical habitat may be much less depending on where the criteria for critical habitat are met. Refer to section 7.1 for a description of how critical habitat within these areas is defined. Field verification may be required to determine the precise area of critical habitat.

eLand Tenure is provided as an approximation of land ownership of the critical habitat unit and should be used for guidance purposes only. Accurate land tenure will require cross referencing critical habitat boundaries with surveyed land unit information.

Appendix C: Effects on the environment and other species

A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making.

Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that recovery strategies may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the recovery strategy itself, but are also summarized below in this statement.

The Least Bittern’s preference for a combination of dense emergent vegetation interspersed with areas of relatively shallow open water, often in remote portions of extensive marshes means that protection of its habitat is largely synonymous with general wetland protection, which would benefit several wetland species (e.g., waterfowl, marsh birds, shorebirds) that use these wetlands for foraging, breeding, staging, resting and/or moulting at certain periods of their annual cycle. Maintenance of the hemi-marsh conditions that Least Bitterns prefer is generally consistent with approaches to enhancing waterfowl and marshbirds habitat (Post and Seals, 2000: Tori et al., 2002; Rehm and Baldassarre, 2007).

It should be recognized, however, that several other species at risk including birds [King Rail (Rallus elegans), Yellow Rail (Coturnicops noveboracensis) and Prothonotary Warbler (Protonotariacitrea)], fishes [Lake Chubsucker (Erimyzon sucetta), Spotted Gar (Lepisosteusoculatus), Pugnose Shiner (Notropisanogenus)], turtles [Blanding’s Turtle (Emydoideablandingii), Spotted Turtle (Clemmysguttata)] and snakes (Eastern Foxsnake (Pantherophis gloydi)] may prefer other types of wetland conditions than Least Bitterns. Management actions should take these competing needs into account, while also recognizing the potential for synergistic recovery actions. Wherever possible, natural ecosystem processes should be maintained and allowed to evolve without human interference as these are the processes that marsh inhabitants are naturally adapted to.

The possibility that the present recovery strategy inadvertently generates negative effects on the environment and on other species was considered. The majority of recommended actions are non-intrusive in nature, including surveys and outreach. We conclude that the present recovery strategy is unlikely to produce significant negative effects.

Abbreviations used in document

AZ: Arizona

CI: confidence interval

COSEWIC: Committee on the Status of Endangered Wildlife in Canada

COSSARO: Committee on the Status of Species at Risk in Ontario

CWS: Canadian Wildlife Service

EC: Environment Canada

ESA: Ontario’s Endangered Species Act, 2007

GRANK: global conservation status rank

HTML: Hyper Text Markup Language

ISBN: International Standard Book Number

IUCN: International Union for Conservation of Nature

ME: Maine

MN: Minnesota

NB: New Brunswick

NHIC: Natural Heritage and Information Centre

NR: not yet ranked

NRANK: national conservation status rank

NWA: National Wildlife Area

ON: Ontario

PDF: Portable Document Format

SAR: Species at Risk

SARA: Canada’s Species at Risk Act

SARO: Species at Risk in Ontario

SE: standard error

SEA: strategic environmental assessment

SOS-POP: Suivi de l'occupation des stations de nidification des populations d'oiseaux en péril du Québec

SRANK: subnational conservation status rank

USFWS: U.S. Fish and Wildlife Service

UTM: Universal Transverse Mercator


Footnotes

  • footnote[i] Back to paragraph Such predators are probably more abundant than they were previously because of subsidized feeding opportunities around human settlements.
  • footnote[ii] Back to paragraph Permanent wetlands include naturally occurring wetlands as well as artificial wetlands managed for conservation purposes.
  • footnote[iii] Back to paragraph This criterion is used by the Quebec Conservation Data Center (NatureServe network) and was recommended by the National Least Bittern Recovery Team in 2009 as the minimum requirement to indicate site fidelity.
Updated: June 17, 2021
Published: November 08, 2016