I love that birding is always a learning experience. If you read the Frontiers of Bird ID mailing list, you may have seen the messages going back and forth regarding mimicry in vireos. Most of us know about mimicry in Mockingbirds, Thrashers, Catbirds, and even Starlings and Blue Jays. I had no idea that vireos were capable of any type of mimicry. Here is an excerpt:
Subject: vireo mimicry
Date: Sun, 13 May 2007 17:26:37 -0700
Tim Spahr's report of a Bell's Vireo song presumably coming from a Warbling Vireo is of interest; I did not run into this specific combination when reviewing vireo songs, so perhaps his will serve as the first known such event. But, what is known is that vireos are excellent mimics and frequently sing all or parts of other species' songs. I assume the songs they mimic are those from their breeding grounds, so it is interesting to ponder the above-mentioned overlap (and subsequent WAVI occurrence in MA on spring migration if it bred near a Bell's Vireo).
I know several examples of vireo mimicry (some of which are documented in BNA accounts, like Yellow-throated and Blue-headed accounts). From personal experience, my favorites are listening to Black-capped Vireos in Hill Country TX where, interspersed in their song are notes from, among others, Acadian Flycatcher, Western Scrub-Jay, etc. One can do the same with White-eyed Vireos; in an almost Mockingbird-fashion, listen to vireo songs and determine how many notes are coming from other species. OK, perhaps I need a life.
Very interesting indeed!