eWestern Birds
The Quarterly Journal of Western Field Ornithologists
A Quantitative Study of Nasal Bristle Length in the Common and Chihuahuan Ravens
Nathan Pieplow and Andrew Spencer
ABSTRACT: The proportionately longer nasal bristles of the Chihuahuan Raven (Corvus cryptoleucus) have been adduced as a character distinguishing that species from the Common Raven (C. corax). In a sample of 113 specimens of the Common Raven and 86 of the Chihuahuan we confirmed that the average of the bristle-to-bill ratio differs significantly in the two species, being 26% greater in the Chihuahuan. But the overlap is wide: only 36% of the Chihuahuan Ravens and 22% of the Common Ravens fell outside the zone of overlap. On the basis of this character, only ravens with a ratio <0.45 can be identified as the Common, while those with a ratio >0.60 are almost all Chihuahuan.