Photos of goatsucker at Crow Valley Campground (Weld) on 6/18 suggest EASTERN WHIP-POOR-WILL

[Joe Roller]

The bird I saw yesterday and mentioned on CObirds has a tail that is much longer than its wingtips, like a whip-poor-will. There is a large, stark-white terminal tail tip on the under tail coverts, suggesting male Eastern, different from the smaller and  buffy tip on Common Poorwill. Regarding Mexican vs Eastern Whip-poor-will, plumage between the two closely related (and recently split) goatsuckers is similar, but the Mexican Whip, from what I read, has less white in the tail than Eastern.

Also there appear to be light colored scapulars, outlined by black streaks, compatible with Eastern Whip-poor-will. The bird did not appear to be particularly large, but in Sibley, most of the size difference between it and Common Poor-will (9.75 inches compared to 7.75 inches) is due to the longer tail length, as the body weight between the two related species (54 g vs 50g) is about the same. That explains why the Crow Valley bird did not appear hefty. 

Also this bird was perched on a fallen limb, a foot off the ground, which Whips do, but Poor-wills? Not so much.

Stray Eastern Whip-poor-wills normally enter Colorado from the east, and Mexican Whip-poor-wills are likely in the SW corner of CO, closer to their normal range in the desert Southwest. 

A birder who camped out there for two nights heard two Poor-wills, from a different area of Crow Valley than were the Whip-poor-will was seen perched, and did not hear a calling Whip-poor-will,

for what that's worth.

Mark Chavez took good images of this bird and will post a link to them on his photo site when he finds time. I am eager to hear other opinions and comments about this tentative ID.

Joe Roller, Denver

PS Both the Latin name "Caprimulgidae" and the vulgar name," goat sucker," come from the explanation goat-herders used when their nanny-goats went dry.