Kirtland’s Warbler government response statement

Protecting and recovering species at risk in Ontario

Species at risk recovery is a key part of protecting Ontario’s biodiversity. The Endangered Species Act, 2007 (ESA) is the Government of Ontario’s legislative commitment to protecting and recovering species at risk and their habitats.

Under the ESA, the Ministry of Natural Resources and Forestry (the Ministry) must ensure that a recovery strategy is prepared for each species that is listed as endangered or threatened. A recovery strategy provides science-based advice to government on what is required to achieve recovery of a species.

Within nine months after a recovery strategy is prepared, the ESA requires the Ministry to publish a statement summarizing the government’s intended actions and priorities in response to the recovery strategy. The response statement is the government’s policy response to the scientific advice provided in the recovery strategy. In addition to the strategy, the government response statement considered (where available) input from stakeholders, other jurisdictions, Indigenous communities and organizations, and members of the public. It reflects the best available local and scientific knowledge, including Traditional Ecological Knowledge, at this time and may be adapted if new information becomes available. In implementing the actions in the response statement, the ESA allows the Ministry to determine what is feasible, taking into account social and economic factors.

Protecting and recovering Kirtland’s Warbler

Kirtland’s Warbler is listed as an endangered species under the ESA, which protects both the bird and its habitat. The ESA prohibits harm or harassment of the species and damage or destruction of its habitat without authorization. Such authorization would require that conditions established by the Ministry be met.

Kirtland’s Warbler is a globally rare, forest songbird that breeds primarily in Michigan, with small breeding populations in Wisconsin and Ontario. In Canada, observations of the species are limited to Ontario and Québec, with breeding only confirmed in Ontario. It is a neotropical migrant that winters in the Bahamas. The Michigan population was in steep decline in the 1960s but has rebounded following creation of additional Jack Pine (Pinus banksiana) habitat by wildfire and specially managed plantations, as well as management of Brown-headed Cowbirds (Molothrus ater) that were parasitizing the nests of Kirtland’s Warbler. The global population has steadily increased from a low of 167 singing males in 1974 to 2,365 singing males reported in the 2015 United States - Canada census area, with the majority observed in Michigan.

Kirtland’s Warbler occurs in very small numbers in Ontario. A Kirtland’s Warbler nest was discovered in 2007 on Department of National Defence lands at Garrison Petawawa in Renfrew County. Additional nests have since been found at this location, with confirmed evidence of breeding for five consecutive years between 2007 and 2011 and the population has persisted since that time. Prior to this discovery, few observations had been reported in Ontario other than an ambiguous report in 1945 from the Barrie area. Recently, observations of Kirtland’s Warblers have been reported at additional locations in central Ontario, including Georgian Bay Township, the District of Parry Sound, the Algoma region, and Simcoe County.

Kirtland’s Warbler has very specific breeding habitat requirements. It prefers expansive tracts of early successional, even-aged, densely stocked Jack Pine with patches of open to sparsely treed areas, but may also occupy Red Pine (Pinus resinosa) in some locations. In terms of stand size, studies have shown that stands 32 hectares or larger are preferred, with improved nesting success in stands larger than 80 hectares. The species is known to occupy areas created by wildfire or plantations designed to mimic wildfires, first appearing when trees are 1.5 m to 2.0 m tall and using the area for 15 to 20 years or until the trees reach 3 m to 5 m in height. As the trees age and the height of their lowest live branches rises, the habitat becomes unsuitable for this ground-nesting bird. Lower branches and ground vegetation are important habitat features as cover for ground nests and as perches. Open patches allow growth of herbaceous ground vegetation, such as Low Sweet Blueberry (Vaccinium angustifolium), Sweet Fern (Comptonia peregrina), Canada Mayflower (Maianthemum canadensis) and various grasses, which conceal nests and provide fruit and insects for foraging. Open and sparsely treed areas provide dispersal areas for Kirtland’s Warbler. Yearlings disperse to younger habitat and sparsely treed areas as the species redistributes from aging habitat into developing habitat areas.

The main threats to Kirtland’s Warbler are a lack of suitable habitat (with fire suppression and forest succession as contributing factors) and brood parasitism. These threats have been well-demonstrated in the Michigan population, but knowledge gaps exist about threats to the species in Ontario. Habitat availability on the wintering grounds has not been identified as a limiting factor to date. Suppression of fire and the resulting forest succession limits the availability of forests that are in the early successional stage needed by Kirtland’s Warbler (i.e., for Jack Pine stand age of approximately 5 to 25 years, for Red Pine approximately 10 to 15 years). The species’ preference for expansive habitat adds to this challenge as sufficiently large tracts of suitable forest are limited in Ontario. Tracts with potentially suitable habitat have been documented in central and northern Ontario, but continued surveying and annual monitoring is needed to determine whether they are occupied by Kirtland’s Warbler.

Knowledge gaps about the habitat requirements of Kirtland’s Warbler in Ontario exist, as research has shown there may be differences between the habitats occupied in Michigan and those in Ontario. The extent to which brood parasitism, which has been a threat to the species in Michigan, is affecting Kirtland’s Warbler at breeding locations in Ontario is unknown.

Given that Kirtland’s Warbler was confirmed to be breeding in Ontario in 2007 and verification is still pending for the observations recently reported at other Ontario locations, information is not yet available to reasonably predict the potential future population size or distribution of this species in Ontario. Continued inventory, monitoring and research is required to increase knowledge about the abundance and distribution of the species, habitat requirements specific to Ontario, and the significance of potential threats to the species in Ontario. As this species depends on early successional habitat, approaches to recovery will also focus on habitat management to support continued availability of suitable habitat in Ontario as occupied forest stands age.

Actions

Protecting and recovering species at risk is a shared responsibility. No single agency or organization has the knowledge, authority or financial resources to protect and recover all of Ontario’s species at risk. Successful recovery requires inter-governmental co-operation and the involvement of many individuals, organizations and communities. In developing the government response statement, the Ministry considered what actions are feasible for the government to lead directly and what actions are feasible for the government to support its conservation partners to undertake.

Government-supported actions

The government endorses the following actions as being necessary for the protection and recovery of Kirtland’s Warbler. Actions identified as “high” will be given priority consideration for funding under the ESA. Where reasonable, the government will also consider the priority assigned to these actions when reviewing and issuing authorizations under the ESA. Other organizations are encouraged to consider these priorities when developing projects or mitigation plans related to species at risk. The government will focus its support on these high-priority actions over the next five years.

As the quality and quantity of Kirtland’s Warbler habitat is diminished over time by forest succession, habitat management will be essential to maintain, and where feasible, increase the availability of suitable habitat to support the persistence of the species in Ontario. Fire suppression and the resulting forest succession changes the habitat from the early successional stage that is required by the species. Habitat has been created on Garrison Petawawa through military training related fires and regeneration of Jack Pine through aerial seeding and hand-planting. In central and northern Ontario, increased representation of Jack Pine and Red Pine has been encouraged through forest management planning in collaboration with foresters, biologists and the forest industry. There may be further opportunities to increase the quality or quantity of suitable habitat in areas where the species has been observed in Ontario, and ongoing habitat management will support continued availability of suitable habitat for the species as currently occupied forest stands age. Where large tracts are not available, smaller sites could potentially be used to contribute to a rotational patchwork of sites that provide habitat and dispersal areas.

Actions:

1. (High) Work collaboratively with public and private land owners, land managers, species specialists, forestry professionals and stewardship organizations to develop, implement and evaluate site-specific habitat management plans in areas where the species has been observed, in particular, locations with confirmed breeding. Plans may include practices such as:
   • identifying habitat-based threats observed at breeding locations (e.g., succession to understorey structure and composition not suitable for the species);
   • enhancing and managing suitable habitat or specially designed plantations with the appropriate tree species, densities and ground vegetation as required by Kirtland’s Warbler using methods deemed to be effective and appropriate for the site (e.g., prescribed burning, removal of trees to create open patches, planting Jack Pine or Red Pine);
   • identifying opportunities to increase habitat availability (in terms of patch size and the availability of dispersal habitat over time);
   • restoring areas with the potential to be suitable habitat near occupied habitat to enlarge the habitat or improve connectivity between habitats; and,
   • implementing best management practices to reduce the level of human activity in occupied breeding habitat during nesting and fledging periods.

There has been confirmed evidence of breeding for five consecutive years (between 2007 and 2011) at Garrison Petawawa, and the population has persisted. It is unknown whether the species is breeding at the locations of the other recent observations in Ontario. Surveys have been conducted to confirm the suitability of potential habitat in large areas of Jack Pine identified through analysis. Continued surveying and monitoring is needed at high-potential sites to determine whether Kirtland’s Warbler are using the habitat for breeding, including the areas of Thessalon, Chapleau, Gowganda, Cartier, Lake Wanapitei, Renfrew County, eastern Algonquin Provincial Park, Manitoulin Island, the Bruce Peninsula, eastern Georgian Bay, North Bay, Barrie and Orillia. Increased knowledge of the species’ abundance and distribution will support more effective implementation of habitat management and threat mitigation actions.

Actions:

2. (High) Inventory and monitor the locations and sizes of breeding populations of Kirtland’s Warbler in Ontario, using standard survey and monitoring protocols, by:
   • conducting targeted surveys at locations with confirmed breeding to monitor changes to the population (e.g., nesting success);
   • conducting presence/absence surveys at locations with reported observations and locations with high probability of suitable habitat; and,
   • documenting habitat characteristics at locations with confirmed breeding and locations with reported observations.

Recent surveys have shown the species occupying what was thought to be suboptimal habitat in Ontario, including stands dominated by Red Pine. Previously, the species was thought to occupy Jack Pine stands almost exclusively. Research is needed to determine whether there are additional habitat differences between the Michigan and Ontario populations. A better understanding of the species’ habitat requirements that are specific to Ontario, including the microclimate and structural features of breeding habitat, will assist in the identification of areas of potentially suitable habitat and priority areas for conducting species surveys and monitoring. Similarly, further research is needed to determine the extent to which the threats experienced by the species in Michigan are threatening the species in Ontario and to inform potential threat mitigation actions. In Michigan, Brown-headed Cowbirds were parasitizing the nests of Kirtland’s Warbler (and the nests of other species) by laying their eggs in the hosts’ nests. This behaviour negatively affects the hosts’ nesting success because the Brown-headed Cowbird hatchlings are fed at the expense of the hosts’ hatchlings. Ongoing collaboration and information-sharing between agencies engaged in species recovery efforts in the United States and Canada can provide information to support the planning of recovery efforts for Kirtland’s Warbler in Ontario.

Actions:

3. Conduct research to determine the extent to which brood parasitism is affecting Kirtland’s Warbler in Ontario. If brood parasitism is confirmed to be a significant threat to Kirtland’s Warbler at Ontario breeding locations, actions may include the development, implementation and evaluation of appropriate methods to mitigate the impacts of brood parasitism.
4. Conduct research to determine the preferred breeding habitat characteristics of Kirtland’s Warbler, including microclimate and structural features. This may include comparing habitat characteristics and population data (e.g., nesting and fledging success, dispersal tendencies, site fidelity) with similar Michigan sites to determine whether there are habitat characteristics that are specific to Ontario.
5. Continue to collaborate and share information between agencies involved with recovery efforts conducted in the United States and Canada to evaluate habitat management techniques for their potential applicability to Kirtland’s Warbler habitat in Ontario and to update survey and monitoring protocols.

Implementing actions

Financial support for the implementation of actions may be available through the Species at Risk Stewardship Program. Conservation partners are encouraged to discuss project proposals related to the actions in this response statement with the Ministry. The Ministry can also advise if any authorizations under the ESA or other legislation may be required to undertake the project.

Implementation of the actions may be subject to changing priorities across the multitude of species at risk, available resources and the capacity of partners to undertake recovery activities. Where appropriate, the implementation of actions for multiple species will be co-ordinated across government response statements.

Reviewing progress

The ESA requires the Ministry to conduct a review of progress towards protecting and recovering a species not later than five years from the publication of this response statement. The review will help identify if adjustments are needed to achieve the protection and recovery of Kirtland’s Warbler.

Acknowledgement

We would like to thank all those who participated in the development of the Recovery Strategy for the Kirtland’s Warbler (Setophaga kirtlandii) in Ontario for their dedication to protecting and recovering species at risk.

For additional information

The government response statement for Kirtland’s Warbler is available in PDF format upon request. Please email PDF requests to recovery.planning@ontario.ca.