The common poorwill (Phalaenoptilus nuttallii) is a nocturnal bird native to western North America. Poorwills are well known for their unique ability to enter short-term hibernation during periods of harsh weather or decreased food availability. Their habitat preferences and behaviors allow them to thrive in arid environments across the western United States.
Natural Range
The common poorwill inhabits a large geographic range spanning much of western North America. Their breeding range extends from British Columbia in Canada south throughout the western United States into northern Mexico. The poorwill’s wintering range is more restricted, with most birds migrating to the southern United States and Mexico. Key states occupied during the breeding season include:
British Columbia | Oregon | Idaho |
California | Nevada | Utah |
Arizona | New Mexico | Texas |
Colorado | Wyoming | Montana |
The common poorwill is found across a variety of habitats within its expansive range. However, it demonstrates preferences for dry, open environments.
Arid Habitats
The poorwill is strongly associated with arid habitats characterized by sparse vegetation and rocky or sandy substrates. Their breeding habitat typically consists of deserts, canyonlands, dry grasslands, open woodlands, and shrub-steppe. This includes ecosystems such as:
- The Mojave and Sonoran Deserts
- Chaparral
- Sagebrush steppe
- Pinyon-juniper woodlands
Within these habitats, poorwills utilize the mosaic of bare ground and low, scattered vegetation. They avoid dense vegetation where agile aerial hunting becomes difficult. The presence of rocks, boulders, and slopes is also important, as these landscape features are used for roosting and nesting.
Vegetation Preferences
Common poorwills are frequently associated with the following plant species and communities:
- Creosote bush
- Sagebrush
- Saltbush
- Yucca
- Oak savannah
- Pinyon-juniper woodland
These vegetation types provide necessary bare ground interspersed with low profile shrubs, small trees, and succulents. This creates suitable foraging habitat and roost sites.
Elevation Range
Common poorwills occupy elevations ranging from near sea level to over 9,000 feet. However, they are most abundant at mid elevations between 2,000 to 6,000 feet. Lower elevations may provide too much dense vegetation, while the highest elevations hold cooler and wetter conditions.
Proximity to Nesting and Roosting Sites
Access to appropriate nesting and roosting sites is a key factor shaping common poorwill habitat selection. They nest on open ground, laying their eggs in sparse vegetation or directly on bare substrate. Nest locations include:
- At the base of shrubs
- Under rock overhangs
- On rocky slopes
- Among gravelly washes
Roosting occurs on the ground, on sloping rock surfaces, or on low perches. Areas with abundant ground crags, rock outcrops, boulders, and canyon walls satisfy nesting and roosting requirements.
Other Habitat Factors
Access to Water
Although poorwills can survive without drinking water, populations thrive where ephemeral water sources are available. These include springs, tinajas (natural rock basins), and rain pools. Access to water may be especially important for feeding nestlings.
Foraging Habitat
Good foraging habitat with an abundance of flying insects is vital. Poorwills often concentrate their feeding activities around washes, floodplains, and areas with bare ground. These locations harbor flying ants, moths, beetles and other prey.
Migration Needs
Migrating common poorwills require stopover habitat that provides sufficient food resources and roosting sites. Areas meeting these needs include desert riparian woodlands and scrub habitats.
Geographic Variation
There is some regional variation in habitat selection across the poorwill’s range:
- Coastal populations in California use chaparral more heavily.
- Poorwills occupy higher elevation woodlands in some mountain ranges.
- Sagebrush steppe is a primary habitat farther north.
However, affinity for semi-arid habitats with rocky areas persists across their range.
Conclusion
In summary, the common poorwill is strongly tied to dry, open habitats across the deserts, grasslands, and shrublands of western North America. Nesting and roosting requirements drive selection of habitats with bare ground interspersed with low vegetation and rocky areas. Proximity to ephemeral water sources and insect prey also shape their habitat preferences. Poorwills thrive in these arid environments thanks to their specialized behaviors and physiology. Their ability to survive without drinking water and enter torpor during harsh conditions allow them to occupy an ecological niche not used by most other bird species.