Eastern Whip-poor-will
(Antrostomus vociferus)
Status: Threatened (COSEWIC 2009, SARA 2011, Ontario ESA 2009)
Species Identification:
The Eastern Whip-poor-will is a nocturnal, insectivorous bird in the nightjar family. It was considered a subspecies of the Mexican Whip-poor-will (Caprimulgus arizonea) until 2010 when it was recognized as a distinct species. The Eastern Whip-poor-will weighs 50 to 55 grams. Their plumage is mottled gray and brown, allowing for camouflage in the forest underbrush. They have large eyes, a small bill, and a wide mouth. Since the Eastern Whip-poor-will is nocturnal they are much more easily heard than seen. During the day it perches silently on a branch or on the ground. They make the sound “Whip-poor-will” loudly and repeatedly throughout dawn and dusk during breeding season, especially on clear nights during a full moon.
Diet:
The Eastern Whip-poor-will swoops from tall branches and catches flying insects with their large open mouths. Their diet is made up of moths, beetles, grasshoppers, stoneflies, and weevils. Foraging time starts 30 minutes after sunset and will continue until they can no longer see their prey, and they will resume feeding about an hour before sunrise. Whip-poor-wills use a “sallying” motion, which means they will keep watch in the treeline and swoop down to catch prey, then return to their perch to feed. Whip-poor-wills will forage in open areas and use mature forests for nesting.
Habitat and Range:
The Eastern Whip-poor-will’s breeding range includes central Saskatchewan, southern Manitoba, Ontario, Quebec, and the Atlantic provinces. It extends into the United States, including most of the northeastern states. Their overwintering range includes the southern parts of Florida and South Carolina, eastern Mexico, and parts of the Caribbean into Panama. Within Ontario, most breeding populations are concentrated in The Land Between, and along the Georgian Bay coastline.
For feeding, Whip-poor-wills do not like forests that are too dense or open areas without any trees. Preferred habitat includes forest edges, regenerating stands (e.g. after a fire), oak savannas, and pine plantations. Breeding sites need to have open ground with canopy cover, shade, and nearby open space for feeding.
Biology and Behaviour:
Whip-poor-wills lay an average of two eggs directly on the forest floor or onto a leaf pile under the protection of shrubs. At about eight days old, hatchlings will molt into plumage that allows them to remain hidden from predators on the forest floor. The female will leave the male to care for the young while she searches for food. Double clutches are more common in southern parts of their range, but sometimes occur in Ontario. Nest sites are hard to locate since they are so well hidden, and can be moved often to avoid predators or other dangers. Both parents will fake an injury to lead predators away from their young. These birds are mostly solitary, but they will form loose flocks during migration.
Similar Species:
- Chuck-will’s-widow: they are a larger bird that is more reddish overall, and they have a white necklace. They are occasionally observed in the southwest corner of Ontario, but historically have been seen in The Land Between
- Common Nighthawk: they differ from the Eastern Whip-poor-will since they have a forked tail and white wing patches
- Common Poorwill: looks similar with similar colouring, but they are only found in western Canada and the United States
Conservation and recovery strategies:
The recovery strategy outlined in 2015 notes the importance of a multi-species or ecosystem-level approach to species at risk recovery, since most bird species that are listed as Species At Risk share the same threats. The plan includes the development and promotion of Beneficial Management Practices for landscape-level planning, especially in the forestry and agricultural sectors. It also prioritizes further research on the distribution and population dynamics of both Whip-poor-wills and the insects they feed on. Further plans outline restoring key habitat, better enforcement of key legislation like the Migratory Birds Convention Act, 1994, and developing partnerships amongst government agencies, interested groups, and private citizens.
Quick Facts:
- The Whip-poor-will call is repeated throughout the night – one patient listener recorded 1,088 rapid successive calls without break
- Eggs are laid in-line with the lunar cycle to allow for good hunting nights when chicks need the most food. During the full moon Whip-poor-wills can hunt the whole night and capture large quantities of insects
- Typical breeding bird surveys are ineffective for detecting the Whip-poor-will, since these birds are silent during daylight hours
Additional Resources:
- Ontario Ministry of Natural Resources fact sheet and 2019 Recovery Strategy
- Birds Canada’s Ontario Whip-poor-will project and Beneficial Management Practices
- Nature Canada’s Whip-poor-will page
- Audubon's species profile
- The 2009 COSEWIC assessment and status report
- The Canada Nightjar Survey is run through WildResearch and Birds Canada
Sources:
Cadman, M.D., D.A. Sutherland, G.G. Beck, D. Lepage and A.R. Couturier (eds.). 2007. Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources, and Ontario Nature, Toronto, xxii + 706 pp.
Environment Canada. 2015. Recovery Strategy for the Eastern Whip-poor-will (Antrostomus vociferus) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. v + 59 pp.
Ministry of the Environment, Conservation and Parks. 2019. Recovery Strategy for the Eastern Whip-poor-will (Antrostomus vociferus) in Ontario. Ontario Recovery Strategy Series. Prepared by the Ministry of the Environment, Conservation and Parks, Peterborough, Ontario. iv + 6 pp. + Appendix. Adoption of the Recovery Strategy for Eastern Whip-poor-will (Antrostomus vociferus), in Canada (Environment and Climate Change Canada 2018).
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