Bushtits Vocalizing & Flicker in Cavity - Arapahoe

[Jared Del Rosso]

I took a short walk along the High Line Canal Trail in Greenwood Village / Centennial (Arapahoe County) this morning. No uncommon species to report, but it was a notable morning for two encounters: a female Northern Flicker hanging out in a cavity in a cottonwood and an active flock of Bushtits. The latter gave emphatic calls when a Sharp-shinned Hawk entered the scene and then again when the hawk departed. 

I didn't react quickly enough to get a recording and couldn't conjure the call now from memory to describe it. But presumably this was what Birds of the World calls the Avian Predator Warning Call: "Sre-e-e-e e-e-e," a "high-pitched warbling call." A 1903 article by Joseph Grinnell is Birds of the World's' source for the description of this call. You can read that article here: https://sora.unm.edu/node/94393. 

A couple of photos and other observations at my blog.

- Jared Del Rosso

Centennial, CO