Friday, June 29, 2012

Chihuahuan Raven

My New Mexican brother is an accomplished herbalist and birder. When I complained that I lacked a photograph of a Chihuahuan Raven, my brother replied that, although difficult to distinguish from Common Ravens, he had it figured out. As you drive north of Silver City, look for Chihuahaun Ravens in dry areas at lower elevations near human habitation. Common Ravens are found higher in the mountains in forested areas. Bednarz and Raitt (2002) agree with my brother's assessment, although they warn that mixed flocks of both raven species and American Crows have been reported. These authors write that the "combination of large flocks in open plain and desert habitats [are] typical only of [the] Chihuahuan Raven."

Chihuahuan Ravens are found from parts of the American Southwest south to central Mexico. In a small, low-elevation town we found what appeared to be an all-black raven. "This all adds up to Chihuahuan Raven," said my brother. Imagine my surprise when I cropped and enlarged this photograph. Not only can you see white bases to the neck feathers (one of the key field marks to the species, marks that are usually hard to see), the lower breast and undertail feathers are also have white bases. I have not seen mention of these later attributes.

The biology of the Chihuahuan Raven is relatively unknown. This bird is social, found in flocks most of the year. They build groups of up to five nests in a single area, but the reasons for this behavior are unknown. Flocks of ravens defend their nests communally. After the nesting season, groups of up to 500 ravens roost together (Bednarz and Raitt 2002).

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