Acadian Flycatcher

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 Strategy for the Acadian Flycatcher (Empidonax virescens) in Ontario was completed on December 14, 2016.

Protecting and recovering Acadian Flycatcher

Acadian Flycatcher 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.

Acadian Flycatcher is a neotropical migrant that breeds primarily in the eastern United States, with approximately one percent of its global breeding range occurring in Canada, specifically in southern Ontario. The Carolinian forest region of Ontario is the northern limit of its breeding range. Its winter range extends from the Caribbean and Central America to northwestern South America. It is considered a common bird in the core of its breeding range, with an estimated global population of over 2 million pairs. The Ontario population is estimated at 35 to 50 pairs and has been relatively stable since 1997 when targeted surveys began. This stability is largely attributed to immigration of birds from the United States to Ontario. Outside of Ontario, the species has experienced annual declines since 1966 and habitat losses due to land development, forestry practices and invasive forest insects and pathogens. If these trends cause the species’ range to contract away from the current periphery, the likelihood of continued immigration to Ontario may be reduced.

Prior to the 1970s, the species was considered a rare, but regular, breeder along the north shore of Lake Erie, particularly in Norfolk and Elgin counties. The species’ historical distribution in Ontario may have been larger prior to extensive conversion of Carolinian forest to agricultural cropland and pasture, but this is unknown as the first Canadian nest records for Acadian Flycatcher are from 1884. Breeding locations in addition to those in Norfolk and Elgin counties were discovered through increased survey effort during the first and second Ontario Breeding Birds Atlases (1981-1985 and 2001-2005) and more recent targeted surveys. Observations within the species’ known distribution reported since 2012 include locations in Norfolk, Elgin, Lambton, Essex, Middlesex and Grey counties in southwestern Ontario and the regional municipalities of York, Halton and Durham in central Ontario. The counties with the greatest number of sites with breeding evidence are Norfolk, Elgin and Lambton counties.

Acadian Flycatcher is an area-sensitive species that prefers extensive tracts of undisturbed, mature deciduous or mixed forests, as well as steep-sided forested ravines. Some research indicates that almost all of the habitat patches that support breeding Acadian Flycatchers in Ontario are larger than 25 ha, and more than half are larger than 100 ha. Fragmentation and increased edge habitat can diminish habitat quality. Its preferred forest habitat is closed canopy, with a relatively open understory and sparse ground cover, typically dominated by some combination of Maple (Acer spp.), Beech (Fagus spp.), Eastern Hemlock (Tsuga canadensis) and Oak (Quercus spp.). It uses a variety of trees for nesting, including American Beech (Fagus grandifolia) and Eastern Hemlock. Sites with permanent or ephemeral ponds or streams are also preferred, as nests are often situated over water. Adults and juveniles forage on a wide variety of insects, insect larvae, and other arthropods.

The greatest threat to the species is the removal, fragmentation or alteration of its habitat. This can be caused by land development, changes to the hydrological regime, and harvest of timber and fuelwood, as well as by invasive plants, insects and pathogens. Residential and agricultural land development, both within habitat and in areas adjacent to habitat, can have a variety of effects on Acadian Flycatcher. These types of development may lead to alteration of vegetation composition, reduced abundance and diversity of prey, human disturbances, brood parasitism and increased predation. Activities that change site hydrology, such as subdivision grading, agricultural tiling, drainage and irrigation may also affect Acadian Flycatcher habitat by lowering the water table. When the ground remains dry for long periods, vegetation may fill in the open understorey and alter the habitat structure. The species is particularly sensitive to the harvest of the largest trees in a wood lot (i.e., diameter-limit harvest; harvesting trees larger than a pre-determined size from a forest or woodlot). This practice changes the habitat structure from the closed canopy and open understorey required by Acadian Flycatcher, and can have long lasting effects with the habitat potentially remaining unsuitable for up to 40 years.

Additionally, invasive plants reduce habitat quality by altering the open understorey and sparse ground cover preferred by Acadian Flycatcher. The negative effects of Garlic Mustard (Alliaria petiolata), Multiflora Rose (Rosa multiflora) and Common Buckthorn (Rhamnus cathartica) have been observed in ravine and woodland habitats north of Lake Erie. Invasive forest pests, such as the Hemlock Woolly Adelgid (Adelges tsugae) and Emerald Ash Borer (Agrilus planipennis), and pathogens such as Beech Bark Disease (Neonectria faginata) and Dogwood Anthracnose (Discula sp.) have the potential to kill large numbers of trees, which could cause extensive reductions in preferred nest trees and canopy cover.

Suitable habitat for Acadian Flycatcher is extremely limited in southern Ontario as very little forest cover in the Carolinian region remains. Many of the remaining woodlots are small (two thirds are smaller than 5 ha) and fragmented, or unsuitable for the species based on alteration of the structure and composition. Acknowledging these limitations, approaches to recovery will focus on maintaining, improving or, where feasible, enlarging remaining habitat and restoring connectivity between fragmented habitat areas. The efficacy of these approaches will be supported by increased knowledge of the species’ distribution and abundance in Ontario, studies of habitat conditions at known breeding sites, research on the ways that land development and tree harvesting alter habitat conditions, and taking a collaborative approach to the development of site specific and broad scale habitat management plans. Given the many land owners and varied land uses in the region, outreach materials are needed to increase awareness of Acadian Flycatcher and promote stewardship of its habitat on publicly and privately owned lands.


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 Acadian Flycatcher. 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.

The habitat required by Acadian Flycatcher is extremely limited in southern Ontario and remaining forests are subject to strong development pressure. Timber and fuelwood harvesting occurs at many of the breeding sites in Ontario, including both publicly and privately owned lands. Continued land development and tree harvesting make it important to identify methods to minimize the impacts of these activities on habitat conditions. Where large tracts are not available, there may be opportunities to enlarge smaller habitat areas or restore habitat connectivity through strategic habitat management planning. Given the species’ need for large, contiguous areas of habitat, and the contextual challenges of highly fragmented forest cover and the high proportion of private land ownership in the region, habitat protection and management efforts will benefit from a collaborative approach.


  1. (High) Work collaboratively with public and private land owners, land managers, municipalities, forestry professionals and stewardship organizations to develop, implement and evaluate site-specific management plans to maintain and improve habitat for Acadian Flycatcher, coordinating actions with existing Carolinian forest bird conservation initiatives, where appropriate. Plans may include practices such as:
    • encouraging the use of silvicultural techniques that minimize alteration to Acadian Flycatcher habitat associated with harvest of timber and fuelwood;
    • planning land use and activities to maintain existing, and where feasible increase the availability of, interior habitat (e.g., large circular core areas) for Acadian Flycatcher;
    • enlarging existing habitat areas and restoring connectivity between fragmented habitat areas;
    • creating a gradual transition between cover types in edge habitats by planting native trees and shrubs and reducing mowing;
    • controlling invasive plants (e.g., Garlic Mustard, Multiflora Rose and Common Buckthorn) posing a direct threat to the habitat conditions required by Acadian Flycatcher at confirmed locations; and,
    • monitoring and managing (as appropriate and feasible) invasive insects and pathogens posing a direct threat to the habitat conditions required by Acadian Flycatcher at confirmed locations.
  2. (High) As opportunities arise, work with local land owners and community partners to support the securement of Acadian Flycatcher habitat through existing land securement and stewardship programs.
  3. Develop, implement and evaluate best management practices to reduce alterations to drainage and moisture conditions in the species’ habitat when conducting activities (e.g., installation or modification of ditches or drainage tile, irrigation projects, site grading, or paving), including activities on land adjacent to Acadian Flycatcher habitat.

Considerable surveying has been undertaken, but habitat modeling indicates that substantial amounts of potential habitat have not been surveyed. Given the high proportion of privately owned land in the region, more information about breeding sites on private land is needed to identify locations where collaborative stewardship could result in larger and more connected habitat across property boundaries. Given the species distribution across southwestern and central Ontario, Traditional Ecological Knowledge from these areas would also help inform future recovery efforts.

Addressing knowledge gaps about the species’ habitat requirements is necessary to inform effective habitat restoration and threat mitigation. For example, there is little information on the habitat used by Acadian Flycatchers during post-fledging and pre-migration stages. At the site scale, monitoring data on population size, nesting success and changes to microhabitat conditions will increase knowledge of how land developments (e.g., agricultural land uses) and tree harvesting affect the species’ habitat and the abundance of prey. At the landscape scale, species surveys, monitoring data and spatial analysis will support the identification of priority locations for application of habitat restoration and threat mitigation techniques.


  1. (High) Conduct targeted surveys at known breeding sites and areas with potentially suitable habitat to gather information on the distribution and abundance of the species in Ontario, which may include information on:
    • population size, nest locations and nesting success;
    • characteristics of the habitat occupied in Ontario (particularly during post-fledging and pre-migration), such as forest age, canopy closure, forest structure, and availability of prey; and,
    • changes to microhabitat conditions (including hydrology).
  2. Conduct a spatial analysis using data about Acadian Flycatcher breeding sites and the locations of potentially suitable habitat within the species’ distribution in Ontario to identify:
    • priority locations for conducting additional targeted surveys; and,
    • strategic locations for implementing habitat stewardship and restoration actions to maintain or increase habitat size and connectivity.
  3. Conduct research to determine the potential impacts on Acadian Flycatcher associated with arthropod (e.g., insects and spiders) abundance and diversity. Studies may include:
    • which arthropod species are consumed by Acadian Flycatcher in Ontario; and,
    • changes to the abundance and diversity of prey species in Acadian Flycatcher habitat, including, if detected, the potential causes of those changes.
  4. Encourage the recording, sharing and transfer of Traditional Ecological Knowledge on Acadian Flycatcher, as available, including information on the condition of the species and its habitat to support protection and recovery.

Increased awareness of Acadian Flycatcher and its habitat is important given the high proportion of privately owned land in the species’ breeding range in southwestern Ontario. As this species may be affected by a variety of activity types that occur on the landscape, it is important that land owners are aware of information resources for woodlot owners and land managers, such as the 2011 Ministry of Natural Resources and Forestry publication, A Land Manager’s Guide to Conserving Habitat for Forest Birds in Southern Ontario, among others. Additional information on stewardship practices that may be implemented on their properties, species’ information, and broader stewardship initiatives in the region, can support effective stewardship efforts.


  1. Work collaboratively with land owners, land managers, forestry professionals, municipalities and stewardship organizations to increase awareness about Acadian Flycatcher, by developing and distributing outreach materials that include:
    • how to identify the species;
    • the species' habitat requirements;
    • protection afforded to the species and its habitat under the ESA;
    • actions that can be taken to reduce threats to the species and its habitat; and,
    • information about forest management strategies and silvicultural techniques to reduce alteration of Acadian Flycatcher breeding habitat associated with harvest of timber and fuelwood.

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 Acadian Flycatcher.


We would like to thank all those who participated in the development of the Recovery Strategy for the Acadian Flycatcher (Empidonax virescens) in Ontario for their dedication to protecting and recovering species at risk.

For additional information

Visit the species at risk website at
Contact your MNRF district office
Contact the Natural Resources Information and Support Centre

The government response statement for Acadian Flycatcher is available in PDF format upon request. Please email PDF requests to