Antrostomus arizonae

Formerly merged with Caprimulgus, but now treated as a separate genus on the basis of genetic data (Han et al. 2010) (AOU 2012). AOU (2010) recognized Caprimulgus arizonae as distinct from Caprimulgus vociferus based on differences in vocalizations (Hardy et al. 1988, Howell and Webb 1995, Cink 2002) and mitochondrial and nuclear DNA (Han et al. 2010); the two species also differ in morphology (Phillips et al. 1964, Howell and Webb 1995, Cink 2002) and egg pigmentation (Phillips et al. 1964).

This species has a small and restricted range in the southwestern United States where it may be of conservation concern. However, it is widespread, known from many localities, and is regularly recorded in Mexico and northern Central America. It is an elusive and poorly known species, and there is limited information about global threats and population demographics. Although there are localized declines in parts of the southwestern U.S. due to large-scale wildfires, it is unlikely that any major threat is impacting its global population.

This species reaches its northern breeding limit in the southwestern United States (Cink et al. 2020). The U.S breeding range includes southern California, southern Nevada, central and southeastern Arizona, central New Mexico and north into the Zuni, Jemez, and Sangre de Cristo mountains (Williams 2010), and extreme western Trans-Pecos Texas. It ranges south through the highlands of Mexico, Guatemala, and El Salvador to Nicaragua (Hruska et al. 2016); also (probably) in southern Baja California, Mexico. It may also breed in Colorado, USA (eBird 2021).

This species overwinters from central Mexico south through the breeding range to Nicaragua, but the northern and southern limits of the wintering range are poorly known (AOU 2010, Cink et al. 2020). It has very rarely wintered north to southern California (Garrett and Dunn 1981).

It is casual in north-central California, southern Alberta, southwestern Saskatchewan, northwestern Montana, and central Colorado (American Ornithologists' Union 1998, Cink et al. 2020, iNaturalist 2021).

This species is likely represented by a large number of occurrences (subpopulations) and is regularly reported across its range (eBird 2021, GBIF 2021).

Habitat loss due to wildfire may be this species’ most significant threat in the southwestern United States. As of 2007, approximately 1.8 million acres of the Gila National Forest have been impacted by fire, and the trend for large-scale fires of over 100,000 acres is increasing (Ruehmann 2017). In Arizona, the Madrean Sky Island region has been impacted by several large wildfires in recent decades that may have negatively affected this species (Ganey et al. 2017). Additional habitat loss in New Mexico by the San Pedro Mine proposed expansion is likely, if this species is present there (Cook 2019). In Southern California, this species occurs on steep mountain slopes and therefore there are no known anthropogenic threats.

Mortality from vehicle strikes has been reported in Eastern Whip-poor-wills in Kansas and Pennsylvania (Santner 1992). Vehicular collisions can be a mortality factor for caprimulgids; of 23 Afrotropical nightjar species, species-specific road mortality ranged from unaffected to very high (Jackson and Slotow 2002), and “great numbers” of mortalities were reported. Caprimulgids are known to frequent roads, and research suggests this association includes use while hunting for insects, resting, and digesting (Jackson 2003), as well as thermoregulation during dark-cold nights, and increased insect intake during bright-warm nights (DeFelipe et al. 2019). The significance of road-kill mortality has not been quantified for Mexican Whip-poor-will.

Significant population declines of migratory aerial insectivores are reported across North America, with multiple stressors and potentially interacting drivers across the annual cycle, including: global declines in aerial insects, environmental contaminates, breeding habitat loss, climate change, and conditions at stopover locations and nonbreeding grounds (Spiller and Dettmers 2019). Threats to this species are poorly understood, but natural system modification and climate change are identified as threats (NMDGF 2016).