King Rail and Least Bittern

Photo: Robert Royce

King Rail and Least Bittern

Photo: Mike Burrell

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.

The recovery strategies for the King Rail (Rallus elegans) and the Least Bittern (Ixobrychus exilis) in Ontario were completed on December 14, 2016. A multi-species approach is being used to efficiently develop the government response statement for these species based on shared ecosystems, threats and biological needs.

Protecting and recovering King Rail and Least Bittern

The King Rail is listed as an endangered species and the Least Bittern is listed as a threatened species under the ESA, which protects both the birds and their habitat. The ESA prohibits harm or harassment of the species and damage or destruction of their habitat without authorization. Such authorization would require that conditions established by the Ministry be met.

King Rail

The King Rail is found as far south as Cuba and Mexico and extending up to southern Ontario. The United States range is patchy and covers much of the eastern half of the U.S. excluding the Appalachian Mountains and most of New England. The species overwinters and resides year-round along the coastal Eastern Seaboard, and in the southern states as far west as Texas, south to Cuba, the Mexican Gulf coast and interior Mexico. In Canada, the King Rail occurs only in Ontario and migrates south following the breeding season. The species has been reported across southern Ontario in the marshes of Bkejwanong (Walpole Island First Nation), in the St. Clair River delta and adjacent Lake St. Clair, in a number of Great Lakes coastal marshes of Lake Erie and Lake Ontario, and in isolated locations in Bruce, Durham, Frontenac, Hastings, Lennox and Addington, Simcoe and York counties.

The King Rail is rare, hard to detect and difficult to observe due to its secretive nature and the relatively inaccessible marshes that it inhabits. Since 2007, there have been a small number of observations of the King Rail in Ontario which inform our current understanding of the species’ distribution. Breeding has not been confirmed in Ontario for over 20 years, but this is likely due to a lack of targeted surveys and monitoring to confirm breeding locations. As a result, little information is available to determine the current abundance and population trends. However, there are no data to indicate a significant change in the distribution and abundance of the species in the province since 2000 when the population was estimated to consist of 30 to 50 pairs. The Ontario population is at the northern periphery of the species’ range and the vast majority of its continental distribution and population occurs further south in the United States. All states neighbouring Ontario have a state status of endangered for King Rail, with the exception of New York where its status is threatened. Populations throughout the species range are suspected to be undergoing a moderate decline. Should the continental population of King Rail continue to experience declines, the species’ range may be expected to contract at its periphery (e.g., Ontario) and shift towards the centre of its range.

Least Bittern

The Least Bittern can be found from southeastern Canada south to Costa Rica, including the Caribbean (Cuba, Hispaniola, Jamaica). Populations in most of its range are migratory but the Least Bittern is a permanent resident from south Florida and coastal Texas south through Central America and the Caribbean. In Canada, the species occurs in Manitoba, Québec, New Brunswick, Ontario, and possibly Nova Scotia, with the majority of Least Bitterns occurring in Ontario. The migratory route of the Least Bittern is unknown, however the species winters from Florida and coastal Texas south through Central America. In Ontario, the species breeds throughout the south, largely south of the Canadian Shield, and locally in the north in the areas of Lake Nipissing, eastern Lake Superior (near Sault Ste. Marie) and in western Rainy River and Kenora Districts near Lake of the Woods.

The 2009 Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessment and status report for the species estimated that there were greater than 500 Least Bittern pairs in Ontario. Additionally, the Ontario Breeding Bird Atlas reported a significant decline of 44% in the probability of observation for the species in the Carolinian region and reported declines that were not statistically significant in the rest of the province between the first atlas (1981-1985) and the second atlas (2001-2005). The Great Lakes Marsh Monitoring Program also found a significant decline in occurrence rates in some areas for the Least Bittern over the past two decades.

Numbers of the species seem to be stable globally, but historically they have declined in Canada and in the northern and central United States. The state status for the species varies widely throughout the United States and in the states surrounding Ontario; its status ranges from endangered to not listed as at risk. While immigration from the United States into Ontario is possible, sufficient habitat would be required to sustain them.

King Rail and Least Bittern

In Ontario, King Rails and Least Bitterns nest in freshwater marshes within emergent vegetation (i.e., aquatic plants rooted in soil with the base of the plant beneath the surface of the water, but with leaves or stems above the water surface) interspersed with areas of open water. Although minimum area requirements are unknown, both species occur most frequently in large marshes, particularly those dominated by cattails (Typha spp.).

Water level depth at nesting sites is important for both species. King Rails require a range of water level conditions as nesting for the species takes place in areas with water depths generally less than 25 cm, but have been observed up to 96 cm and foraging areas generally have shallower water depths than nesting, with some dry areas and dense cover. Least Bitterns nest in areas with water depths ranging between 10-50 cm. Water levels must be relatively stable throughout nesting as sudden changes can flood nests, reduce foraging opportunities and enhance access for predators.

Both King Rail and Least Bittern are subject to similar threats based on their habitat and biological needs. The species are threatened by the loss or degradation of suitable habitat, primarily due to human impacts. Loss or degradation of habitat may be caused by development, conversion of land to agricultural uses, introduction of invasive species, declines in species that create and maintain preferred habitat conditions (e.g., Common Muskrat (Ondatra zibethicus)), impaired water quality and improper water level management. Fragmentation of habitat may also result in increased predation, which has been identified as a threat to King Rail recovery, by allowing enhanced access for predators. In addition, in some areas of the United States, hunting for King Rails is permitted and the impact of this on migration corridors and wintering grounds remains undocumented. Infrequent and unpredictable disturbances due to recreational activities (e.g., waves from motorized watercrafts) or collisions with cars and man-made structures may also be potential threats to both species.

Invasive species such as European Common Reed (Phragmites australis ssp. australis), Purple Loosestrife (Lythrum salicaria), Reed Canary Grass (Phalaris arundinacea), Eurasian Frog-bit (Hydrocharis morsus-ranae), Eurasian Water-milfoil (Myriphyllum spicatum), and a hybrid version of cattails (Typha x glauca) can alter and degrade wetland habitat. Large populations of the invasive Common Carp (Cyprinus carpio) create turbid, cloudy water conditions in wetlands, with decreased submerged aquatic growth and less prey. For species such as the Least Bittern that uses visual cues to detect their prey, this may impact their ability to forage.

Furthermore, the alteration or regulation of water levels influences the amount of suitable habitat for both species, as water level fluctuations influence the overall diversity and condition of wetland plant communities. Water levels with natural variations (i.e., containing more year-to-year variation) are important for maintaining long-term breeding habitat within Great Lakes coastal wetland marshes. For Lake Ontario and the upper St. Lawrence River, the regulation plan that had been in place had limited water level variation and altered coastal ecosystems. In December 2016, the International Joint Commission approved Plan 2014, a new plan for managing water levels in Lake Ontario and the St. Lawrence River. Plan 2014 helps restore plant diversity and habitat for fish and wildlife, such as the King Rail and Least Bittern in Lake Ontario and the St. Lawrence River by allowing more natural variability in water levels.

It is uncertain how much suitable habitat is available to King Rail in Ontario, as specific habitat requirements are not known and apparently suitable habitat is not known to beoccupied. Research is needed into the biology and habitat requirements of the species to determine where habitat management, restoration and threat mitigation would be most effective. Habitat protection and mitigation of threats is essential to the recovery of the Least Bittern. Marsh management programs and habitat stewardship have been important in the restoration and maintenance of suitable habitat for both the Least Bittern and King Rail. In particular, habitat management that supports fluctuating water levels and creates interspersion are important. In addition to the continued conservation of natural wetlands, restoration or creation of wetlands may create additional suitable habitat, which may enable increases to the species’ populations or distributions.

Approaches to recovery for both species will include protecting the species and their habitat, managing threats and implementing best management practices in collaboration with local landowners, partners, and Indigenous communities and organizations. Furthermore, approaches will include filling knowledge gaps by conducting monitoring to determine distribution and abundance, and conducting research on habitat requirements, threats and effectiveness of threat mitigation. The Ontario population of both species occurs at the periphery of their continental range, and distribution of the species in Ontario may be influenced by population changes at a continental level. This effect may be more pronounced for the King Rail, as populations in the neighbouring states are small and declining. Therefore, working collaboratively with other jurisdictions will be important for the recovery of the species.


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 the King Rail and Least Bittern. 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.

Research gaps remain on habitat requirements for the King Rail and Least Bittern in Ontario. A greater understanding of the species’ habitat requirements will help to target where threat management will be the most effective and help to identify and investigate threats to the species. One such threat includes native vegetation being replaced or outcompeted by invasive emergent vegetation such as European Common Reed. Paired with a lack of water level fluctuations, invasive emergent vegetation can form single-species vegetation stands that decrease the patches of open water, decrease the diversity of vegetation, reduce the availability of prey, as well as reduce the availability of nesting sites. Implementing best management practices in appropriate habitat will help to mitigate this and other threats. The Government of Ontario has developed best management practices to control the invasive plant European Common Reed. Additionally, under the Invasive Species Act, it is illegal to import, breed/grow, buy, sell, lease or trade European Common Reed. Best management practices have also been developed for Reed Canary Grass. Restoration of wetlands and adjacent areas used by the species will add resiliency and may increase the quality of habitat. Additionally, research into factors that may be limiting the distribution and abundance of the King Rail will help to identify approaches to assist in recovery.


  1. (High) Develop, promote, implement and evaluate best management practices to maintain and restore habitat for King Rail and Least Bittern such as:
    • implementing best management practices for invasive species prevention or control (e.g., European Common Reed), in areas where invasive species pose a direct threat, while evaluating and adapting approaches to minimize impacts on specialist marsh birds such as King Rail and Least Bittern;
    • implementing best management practices to reduce effects of siltation, turbidity, nutrient loading, and pollutants (e.g., shoreline stabilization techniques, implementing Environmental Farm Plans and Nutrient Management Plans) on wetlands; and,
    • developing, implementing and evaluating techniques for wetland restoration, wetland creation and restoration of areas adjacent to wetlands.
  2. Identify and describe King Rail and Least Bittern habitat and micro-habitat conditions, including:
    • identifying habitat characteristics for all life stages such as foraging, post-breeding dispersal, moulting (i.e., replacing old feathers with new feathers) and migration stopover in Ontario;
    • identifying territory, home range size and if feasible minimum area requirements;
    • estimating available suitable habitat to determine if habitat specificity is a limiting factor for the King Rail; and,
    • investigating use and habitat availability changes with increasing and compounding threats (e.g., climate change, water level alterations, invading and established species).
  3. Research potential factors that may be influencing the distribution or abundance of King Rails and Least Bittern such as:
    • investigating prey specialization, competition with other species for prey or nesting locations, and predator density for King Rails; and,
    • researching dispersal and migration routes.
  4. Examine the interaction between occupancy or nesting success and water level fluctuations over appropriate time scales to investigate how water level management (e.g., dykes, dams or regulated water levels) impacts habitat availability.

The King Rail and Least Bittern are secretive species that inhabit large marshes, which are difficult to survey and detect. Conducting surveys either through volunteer monitoring programs or using a species-specific survey will help to provide information on the distribution and population size of the species. Ongoing monitoring is required to track progress and effectiveness of recovery actions. Using consistent species-specific methods will result in higher detection rates and help support a greater understanding of species trends.


  1. (High) Develop and implement a species-specific monitoring program using standardized protocols in areas with confirmed observations of King Rail and Least Bittern in order to model population densities, population trends and habitat trends.
  2. (High) Conduct species-specific surveys in King Rail suitable habitat to determine the presence/absence of the species and better understand the species’ distribution and population size.
  3. Collaborate with volunteer monitoring programs to better assess the population size and distribution of Least Bittern and address gaps in the current known range.
  4. Encourage the recording, sharing and transfer of Traditional Ecological Knowledge on King Rail and Least Bittern, as available, including information on the condition of the species and its habitat to support protection and recovery.

Many wetlands, particularly in southern Ontario are privately owned. Wetland conservation for the King Rail and Least Bittern will be strengthened by the support of various partners, landowners, land managers and Indigenous communities and organizations. Providing information on the species biology may help landowners mitigate potential threats to the species. For instance, disturbances from recreational activities can disrupt activities such as foraging or cause nest abandonment. In addition, the Least Bittern flies at low heights and migrates at night making the species susceptible to collisions with vehicles and infrastructure. King Rail may also be susceptible to similar collisions. Many organizations and institutions are already involved in the conservation of wetlands and conducting wetland stewardship work. Leveraging existing programs and working collaboratively across jurisdictions will help us to coordinate efforts for the recovery of these species.


  1. (High) Coordinate efforts to share information with other jurisdictions, including national and international partners for wetland conservation, to increase understanding of potential range contractions across the continent and of the protection of migratory and overwintering habitat of King Rail and Least Bittern.
  2. As opportunities arise, support the securement of habitat of King Rail and Least Bittern through existing land securement and stewardship programs.
  3. Promote local stewardship of King Rail and Least Bittern habitat and increase awareness of the species’ biology to landowners and land managers by:
    • collaborating with existing wetland conservation programs to promote the stewardship and conservation of wetland habitat;
    • developing and implementing strategies (e.g., information distribution, road signage) to minimize collisions with vehicles or infrastructure;
    • encouraging landowner and land manager participation in citizen science programs; and,
    • reducing the effects of recreational activities (e.g., motorized boat waves near marshes).

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 the King Rail and Least Bittern.


We would like to thank all those who participated in the development of the Recovery Strategy for the King Rail (Rallus elegans) in Ontario, and the Recovery Strategy for the Least Bittern (Ixobrychus exilis) in Ontario for their dedication to protecting and recovering species at risk.

For additional information

The government response statement for King Rail and Least Bittern is available in PDF format upon request. Please email PDF requests to