[cobirds] Ode to Petrochelidon Caution

Good afternoon, Colorado birders. 

I want to issue a word of caution when identifying swallows of the genus Petrochelidon (Cliff and Cave Swallow as we know them in English). In June through at least early September, millions upon millions of young Cliff Swallows whom have not fully attained adult plumage are migrating south through the Great Plains, where a sizeable percentage of this species' total population breeds. Because these young birds sport golden/bronze forehead and throat patches of the same color and of varying shades depending on age, they are extremely difficult, if not impossible at times to distinguish from young or adult Cave Swallows. They also show a stronger buffy wash in the underparts than adults, and the undertail coverts are often very weakly marked, two features often incorrectly associated with just Cave Swallows. Some sources that should demonstrate this well are Sibley and better yet, eBird's Macaulay library. Over this last week, I would have given almost anything to have photographed the fencelines upon fencelines of young, variable Cliff Swallows I observed over the summer, so I could better demonstrate my point.

So please, when reporting a Cave Swallow in Colorado, provide excellent photographic or auditory documentation. This post is not meant to disparage or discredit initial reports of Cave Swallow at John Martin Reservoir. However, knowing the tendency of swallows, if there was a Cave Swallow at John Martin at some point, the chances of it sticking around for several days at the same spot seem slim. All of the photos I've seen reported as Cave Swallow from the location have either been poor and inconclusive, or have been nice photos of an immature Cliff Swallow.

Happy finding and documenting rarities, and stay smart and healthy in these times.

David Tonnessen

Colorado Springs

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