As usual, I must second Ted's thoughts. Nasty is right about this complex - Mike Lanzone and I recorded flight calls of Black-headed Grosbeak, Western Tanager and Bullock's Oriole in Arizona in 2005, and the variation was staggering. On subsequent (and previous actually) trips to the SW, I
Good stuff, Andrew! A few things: 1. "Ted's clips" of Brewer's Sparrows are actually Nathan Pieplow's. 2. Interesting to compare Andrew's observations in Catron County, NM, with observations from "up north" in Colorado. Pretty convergent, on the whole, I would say. 3. Andrew says "presumed"