Comments:

Chihuahuan Raven 2010-14

Sorry, I’m late jumping into the discussion on this record. I was hoping to gather some close-up photos of Common Ravens but haven’t had the opportunities I’ve hoped. Anyway, I have strong reservations about this record, and believe there is not enough evidence to accept this record. In my opinion, the bill proportions (size and shape) and extent of rictal bristles along the bill do not differ significantly from a Common Raven (or at least any Common Ravens I’ve been able to compare (see below)). While the base of the neck feathers were described as white, this character can sometime be difficult to differentiate from the ‘pale gray’ bases of neck feathers typical of Common Ravens. I’ve been tricked several times while observing ravens in southern Colorado and southeast Arizona, as the apparent color of the base of neck feathers change under various lighting conditions.

Figures 1 and 2 are of Common Ravens photographed in Washington County and Figure 3 is ‘Photo A’ from the possible Chihuahuan Raven record 2010-14.

I used Figures 2 and 3 below and compared measurements of bill length, depth, extent of rictal bristles (proportionate to size of eye, head, etc.) and did not find any appreciable differences between the bill / rictal bristles length of the two ravens. Next (and take this for whatever you may), I tried using Photoshop to overlay the head and bill of the bird in Figure 3 with the Common Raven shown in Figure 2. I didn’t change the proportions: just copied, pasted, rotated, and resized, so I could directly compare relative bill size and shape, and rictal bristle length (Figures 4 and 5). (I’m not a wizard on the physics of photoshop, but I think this provides a nice comparison). Again, there was no appreciable difference in the size and shape of the bill and extent of the rictal bristles of the two birds.
 

Figure 1. Common Raven, Zion Canyon, Washington Co., UT (February 2009).

Figure 2. Common Raven, Quail Creek State Park, Washington Co., UT (May 2010).

Figure 3. Possible Chihuahuan Raven, Canyonlands N.P., Grand Co., UT (April 2010), photo by John Fitzpatric.

Figure 4. Common Raven (Fig. 2) overlaid with head of raven shown in Figure 3.

Figure 5. Common Raven overlaid with head of raven shown in Figure 3.