Answer:

This all-black large bird with a big bill immediately rules out all North American birds except Corvids. Furthermore, the all-black plumage narrows us down to crows and ravens. The shaggy throat, large bill, and wedge-shaped tail tells us it’s not an American Crow (or Fish Crow or Tamaulipas Crow which are not found in New Mexico). In New Mexico, this leaves us with two possibilities: Common Raven and Chihuahuan Raven.

These two species are very difficult to tell apart, much more difficult than implied by most field guides. Unless you live in an area where you encounter both species all the time, if you visit an area where both species are found and you never put “Raven Sp.” into eBird, there’s a good chance you are fooling yourself.

A key field mark of Chihuahuan Raven, shown in all the field guides, is Chihuahuan Raven’s neck feathers are white at the base, and this is usually visible only when the wind blows the black feather tips out of the way. In fact, Chihuahuan Raven used to be called “White-necked Raven” for this feature. We can see in this bird that the wind is indeed blowing on the neck, showing white feather bases underneath. So we have a Chihuahuan Raven, right?

Not so fast. One thing that is only sometimes mentioned in field guides, and usually not illustrated, is that Common Raven has pale gray bases to the neck feathers, as opposed to white in Chihuahuan Raven. Trying to distinguish pale gray from white is very difficult in all but perfect lighting. In photos it’s even worse, since a photo of a black bird often overexposes any part of the bird that is not black, and pale gray can easily look white. Conversely, underexposing can make white look pale gray. Backlit birds, like the one shown here, are especially difficult.

For example, here is a photo of two Common Ravens at Quail Lake, in Los Angeles County, which is very far from the range of Chihuahuan Raven. The wind is exposing neck feathers that appear whitish.

So what about other features? Our bird has a very large bill, with nasal bristles extending a bit less than halfway down the bill. Also, even though the photo is at an angle, the tail has a very pronounced wedge shape. In Chihuahuan Raven, the wedge in the tail is shallower than in Common, and the nasal bristles are average longer, extending more than halfway to the tip of the bill. There are other features that you can’t tell from the photo (e.g. The two species also have slightly different vocalizations that one can learn to tell apart, the habitat preferences are different, and Chihuahuan Raven is more gregarious.) So our bird is a Common Raven.

Here’s a Chihuahuan Raven in open country in Arizona, near the New Mexico border. One thing that stands out is the length of the nasal bristles compared to the bill, and also the tail is more square.

Congratulations to Alex, Ben, Naresh, and Alexandra for figuring out Common Raven!