Mexican Whip-poor-will Life History

Habitat

Mexican Whip-poor-wills are primarily birds of mountain forest and woodland. In Mexico, they breed in humid to semiarid pine and pine-oak forest from about 4,600–9,800 feet, and probably move downslope to foothill woodland and forest during winter. In Arizona and New Mexico, this species breeds most frequently in pine-oak woodland from 5,500–6,500 feet and is often encountered in wooded canyons. In California, Mexican Whip-poor-wills inhabit forested hillsides with a mix of oaks and conifers between 3,900 and 6,000 feet, and occur in white fir–pinyon pine forest at 7,900 feet. In west Texas, Mexican Whip-poor-wills use thickets in brushy canyons as well as pine-juniper-oak woodland on mountain slopes.

Food

Mexican Whip-poor-wills probably forage like Eastern Whip-poor-wills, which feed primarily by sallying for flying insects from a perch (or sometimes from the ground). Eastern Whip-poor-wills start foraging about 30 minutes before sunset, and when there is enough moonlight, they will continue all night long. They catch a diversity of night-flying insects, with moths and scarab beetles being their main prey.

Nesting

Nest Placement

Mexican Whip-poor-wills lay their eggs on leaf litter. They may place the eggs close to a rock or plants that can provide shade from afternoon sunlight.

Nest Description

Mexican Whip-poor-wills do not build a nest, instead laying their eggs directly on leaf litter on the ground. In ponderosa pine forest, the nesting site is often on gravelly soil and forms a slight depression.

Nesting Facts

Behavior

Mexican Whip-poor-wills are nocturnal, roosting on the ground or low tree limbs during the day and then becoming active at dusk to catch night-flying insects. This species is very poorly known, so many aspects of its life history have not been documented; currently, scientists can only presume that its behaviors and breeding biology are similar to the closely related Eastern Whip-poor-will.

Eastern Whip-poor-wills are socially monogamous, and some pairs breed together for several years in a row. Before nesting begins, pair members move around their territory and roost together. Research in Ontario suggests that the breeding cycle is synchronized with the lunar cycle, with hatching often about 10 days before a full moon. This provides adults with maximum moonlight to catch insects for newly hatched chicks. Both adults brood and feed the chicks, which can move short distances even at a young age.

Conservation

Partners in Flight estimates Mexican Whip-poor-will’s global breeding population at 190,000 individuals. PIF rates this nightjar a 14 out of 20 on the Continental Concern Score, placing it on the Yellow Watch List for species with restricted ranges.

Little is known about Mexican Whip-poor-will conservation. But many North American aerial insectivores, including Eastern Whip-poor-will, have declined significantly in recent decades. Conservation biologists believe that several factors, including decreased prey abundance, environmental contaminants, habitat loss, climate change, and migratory stopover and wintering ground conditions, could be working together to cause these declines. Several groups of birds, including nightjars, have had major declines since 1970, so it is possible that Mexican Whip-poor-will might also belong on the list of declining insectivores, but population trend data have been lacking for this species. The Nightjar Survey Network offers opportunities for volunteers to collect data on Mexican Whip-poor-wills to help fill this information gap.

Credits

Chesser, R.T., Banks, R.C., Barker, F.K., Cicero, C., Dunn, J.L., Kratter, A.W., Lovette, I.J., Rasmussen, P.C., Remsen, J.V., Rising, J.D., Stotz, D.F. and Winker, K. (2010). Fifty-first supplement to the American Ornithologists’ Union Check-List of North American Birds. Auk 127(3): 726-744.

Cink, C. L., P. Pyle, and M. A. Patten (2020). Mexican Whip-poor-will (Antrostomus arizonae), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.

Cleere, N. (1998) Nightjars: a guide to nightjars, nighthawks, and their relatives. Yale University Press, New Haven, Connecticut.

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Holyoak, D. T. (2001) Nightjars and their allies: the Caprimulgiformes. Oxford University Press, Oxford, United Kingdom.

Howell, S. N. G., and S. Webb (1995). A Guide to the Birds of Mexico and Northern Central America. Oxford University Press, New York, NY, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Spiller, K. J., and R. Dettmers (2019). Evidence for multiple drivers of aerial insectivore declines in North America. Condor: Ornithological Applications 121: 1–13

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