Description of residence for Acadian Flycatcher (Empidonax virescens) in Canada

Section 33 of the Species at Risk Act (SARA) prohibits damaging or destroying the residence of a listed threatened, endangered, or extirpated species. SARA defines residence as "a dwelling-place, such as a den, nest or other similar area or place, that is occupied or habitually occupied by one or more individuals during all or part of their life cycles, including breeding, rearing, staging, wintering, feeding or hibernating" [s.2(1)]. With respect to a listed wildlife species that is an aquatic species or a species of bird protected under the Migratory Birds Convention Act, 1994, the prohibition applies wherever residence of the species is found. For any other listed wildlife species, the prohibition applies automatically when the residence of the species is on federal lands and will only apply on non-federal lands if an order is made pursuant to sections 34 or 35 of SARA. Under section 97 of SARA every person who contravenes section 33 of the Act commits an offence.

The following is a description of residence for the Acadian Flycatcher (Empidonax virescens), created for the purposes of increasing public awareness and aiding enforcement of the above prohibition. Acadian Flycatchers are known to have one type of residence – the nest.

Species information

Scientific name
Empidonax virescens
Common name
Acadian Flycatcher
Current COSEWIC status & year of designation
Endangered 2000
Occurrence in Canada
Rationale for designation
This species breeds in Canada in very small numbers. There are few remaining patches of habitat sufficiently large and of adequate quality to sustain breeding populations; threats to this habitat are continuing.Footnote 1
Figure 1. Known distribution of the Acadian Flycatcher (Empidonax virescens) in Canada.
Image of map (see long description below)
Long description for Figure 1

Figure 1 shows a map of southern Ontario where the species distribution occurs. It occurs within most of the southern tip of Ontario; from Hamilton to Sarnia and from Niagara falls to Leamington. It does not occur near Windsor Ontario. Four other small patches are found: in Toronto, near Orangeville, near Cannington, and near Nephton.

1 The nest

Physical appearance and context

Any place used as a nest by the Acadian Flycatcher is considered a residence. The Acadian Flycatcher is an area-sensitive, neotropical migrant songbird that, in Ontario, typically nests in large, mature, swampy woods and mature, well-wooded ravinesFootnote 2. The nest is located in a forest having a closed, or nearly closed (>70%) canopy, and an open understoryFootnote 2,Footnote 3. The cup-like nest is generally built at low heights (2–4 m) in the fork of a horizontal branch which is often suspended over water and sometimes over a path or a small clearingFootnote 2,Footnote 8. Nests appear unkempt and loosely built, with grass and other nest materials sometimes hanging in streamers below the nestFootnote 6. At least fourteen nest tree species are used in Ontario, including American beech (Fagus grandifolia), sugar maple (Acer saccharum), hawthorn (Crataegus) and eastern hemlock (Tsuga canadensis) Footnote 4,Footnote 5,Footnote 7.

Figure 2. Acadian Flycatcher nest
photo of Acadian Flycatcher nest


The nest provides a container in which adult flycatchers lay and incubate eggs, and rear hatchlings. The nest may also play a role in courtship and pair formation during nest constructionFootnote 6. The adult female builds the nest, usually over 3-4 days but sometimes over two weeksFootnote 6. Clutch size in Ontario averages about 3 eggsFootnote 7, which are creamy or buffy white in colour and sparingly marked with small brownish spots mainly at the larger endFootnote 4. Eggs are incubated for 13-15 days by only the femaleFootnote 4. All young tend to hatch within a single day and remain in the nest for 12-18 daysFootnote 4.

Damage/destruction of residence

Federal Policy defines damage or destruction of a residence as:

Any alteration to the topography, geology, soil conditions, vegetation, chemical composition of air/water, surface or groundwater hydrology, micro-climate, or sound environment which either temporarily or permanently impairs the function(s) of the residence of one of more individuals.

Any activity that destroys the function of the nest would constitute damage or destruction of the residence. This would include, but is not limited to, moving or otherwise disturbing the eggs, nest, and nest tree; changing the microclimate of the nest (such as the amount of light or internal temperature); or blocking access to the nest. The reasons why Acadian Flycatchers prefer nest sites with intact, or nearly intact, canopy cover and proximity to water are not well understood but may be related to food availability and/or nest microclimateFootnote 8. Activities that remove canopy cover or eliminate water availability near the nest can damage its ability to function as a residence.

Period and frequency of occupancy

Acadian Flycatchers return to Ontario from wintering areas in mid MayFootnote 4, with females typically arriving a few days later than malesFootnote 6. Nest construction begins in late May or early June, and the nest site can be used for a minimum of five weeksFootnote 4,Footnote 8. Double-brooding is a common occurrence in OntarioFootnote 7; parents usually build another nest and extend the active breeding season to the end of August. Adults exhibit high fidelity to breeding sites, regularly returning to previously used habitats in subsequent yearsFootnote 4,Footnote 8. Protection should include nest building, egg laying, incubation, hatching, nestling, and brood rearing periods – a total time frame of approximately 90 days.

Additional information

For more information on the Acadian Flycatcher, please visit the species' profile.

For more information on SARA, please visit the SAR Registry.

Recommended citation

Please cite this document as:

Government of Canada. Species at Risk Act Public Registry. Residence Descriptions. Description of residence for Acadian Flycatcher (Empidonax virescens) in Canada. July 2007. (Access date).


Footnote 1

James, R.D. 2000. Update COSEWIC Status Report on Acadian Flycatcher, Empidonax virescens, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 8 pp.

Return to footnote 1 referrer

Footnote 2

Martin, D., J. McCracken and M.Cadman. 1999. Acadian Flycatchers in Ontario ravines. OFO News 17(2): 10-12.

Return to footnote 2 referrer

Footnote 3

Friesen, L.E., D. Martin, M.D. Cadman, P. Carson, K. Elliott, M. Gartshore, J. McCracken, P. Prevett, B. Stutchbury, D. Sutherland and A. Woodliffe. 2000. National recovery plan for Acadian Flycatcher (Empidonax virescens) and Hooded Warbler (Wilsonia citrina). National Recovery Plan No. 20. Recovery of Nationally Endangered Wildlife (RENEW). Ottawa, Ontario.

Return to footnote 3 referrer

Footnote 4

Dave Martin, personal communication.

Return to footnote 4 referrer

Footnote 5

Bisson, I.A., D. Martin, and B.J.M. Stutchbury. 2000. Acadian Flycatcher, Empidonax virescens, nest site characteristics at the northern edge of its range. Canadian Field-Naturalist 114: 689-691.

Return to footnote 5 referrer

Footnote 6

Whitehead, D. R. and T. Taylor. 2002. Acadian Flycatcher. In The Birds of North America, No. 614 (A.Poole and F.Gill, eds.) Philadelphia: The Academy of Natural Sciences; Washington, D.C.

Return to footnote 6 referrer

Footnote 7

Woolfenden, B. and B. Stutchbury. 2004. Population status and productivity of Acadian Flycatchers in the Carolinian forest. Report to the Acadian Flycatcher/Hooded Warbler Recovery Team.

Return to footnote 7 referrer

Footnote 8

Bonnie Woolfenden, personal communication.

Return to footnote 8 referrer