Common Poorwill
Phalaenoptilus nuttallii
Summary 7
The Common Poorwill (Phalaenoptilus nuttallii) is a nocturnal bird of the family Caprimulgidae, the nightjars. It is found from British Columbia and southeastern Alberta, through the western United States to northern Mexico. The bird's habitat is dry, open areas with grasses or shrubs, and even stony desert slopes with very little vegetation.
Distribution 8
Common poorwills range throughout western North America from south central British Columbia and southwestern Saskatchewan to central Mexico. Northern populations migrate to the southern portions of their range, from California, Arizona, and Texas to central Mexico, from September to November and return April to May. This migration may vary by a month depending upon weather conditions and the portion of the breeding range occupied. Southern populations arrive for breeding season from February to March and leave October to November for their winter range. Some southern populations occupy the same region year round but migrate to higher elevations for the breeding season and to lower elevations during the winter.
Biogeographic Regions: nearctic (Native )
Morphology 9
Common poorwills are medium-sized birds with an adult length of 19 to 21 cm. The average mass within a sample of Phalaenoptilus nuttallii in British Columbia was 47.2 +/- 6.0 grams for males and 49.5 +/- 6.3 grams for females. Average wing span in that sample was 42.7 cm for males and 44.1 cm for females. Weight ranges vary among populations and with the time of year. Males lose weight early in the breeding season and both sexes gain weight prior to migration. The size of males and females is similar with females tending towards slightly larger average measurements than males.
Overall color ranges from mottled brown and white to mottled black and white patterns. The ventral side is grey-white with thin charcoal lateral bands progressing to a dark band at the throat. The dorsal surface has cryptic mottled pattern in grey, black, and brown shades and the lateral tail feathers have black and brown bands with white or dun colored tips. The wings are sandy and brown barred at the dorsolateral trailing side and mottled on the medial leading edge. The beak has a ventral curve, is short and wide, and has large open gape with pronounced bristles extending laterally from base.
The species can be distinguished from other members of the Caprimulgidae family in North America by a thicker white throat patch and short tail length. The wingtips extend to the end of the tail when folded, and a large head appears to transition to body without a neck, giving them a stout appearance. The other members of this family have a longer tail extending past the wingtip and do not have the typical lateral white or buff coloured rectrices found in common poorwills. Males and females are relatively monomorphic with only small distinguishing characteristics such as white tipped rectrix feathers for males and buff for the females. Juveniles have similar appearance to adults as well.
Common poorwills are polytypic, with five described subspecies based in large part upon geography even though the winter ranges appear to overlap. However, the existence of subspecies is debatable without additional genetic research. In addition, light and dark morphs exist throughout the range making differentiation, based upon appearance, between subspecies and morphs difficult.
Range mass: 42.8 to 58.1 g.
Average mass: 51.6 g.
Range length: 19 to 21 cm.
Average wingspan: 42.7 to 44.1 cm.
Average basal metabolic rate: 0.8 cm3.O2/g/hr.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: sexes alike; female larger; sexes colored or patterned differently
Habitat 10
Common poorwills are found in dry, open areas in diverse habitats such as grasslands, forest, hills, and deserts. Vegetation varies, with preference given to short grasses and shrubs or open forest in areas with deciduous or coniferous growth. Trees or shrubs reported in proximity to nesting and roosting areas include, but are not limited to, such species as white fir, ponderosa pine, trembling aspen, Jeffrey pine and creosote. Roost sites are chosen for proximity to bare ground, vegetative debris, and are usually open with little live vegetation cover. Common poorwills typically nest at elevations between 500 to 1000 meters, with some found over 2500 meters.
Range elevation: 500 to 2500 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; scrub forest ; mountains
Sources and Credits
- (c) Jerry Oldenettel, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/7457894@N04/1193859183
- (c) Ken-ichi Ueda, some rights reserved (CC BY-NC), http://farm3.static.flickr.com/2444/4046123018_d371257929.jpg
- (c) Ken-ichi Ueda, some rights reserved (CC BY-NC), http://farm3.static.flickr.com/2504/4046120944_6918a5795e.jpg
- (c) Jerry Oldenettel, some rights reserved (CC BY-NC-SA), http://farm5.static.flickr.com/4012/4363317480_548d91ddf9.jpg
- (c) Bryant, some rights reserved (CC BY-NC), http://farm7.static.flickr.com/6124/5956975588_111fef5e3b.jpg
- (c) Bryant, some rights reserved (CC BY-NC), http://farm7.static.flickr.com/6138/5956976520_8bac2c5471.jpg
- (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Phalaenoptilus_nuttallii
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31414760
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31414762
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31414761
