Brown-crested Flycatcher, Myiarchus tyrannulus
Brown-crested Flycatcher, 8/6/08, Fort Lowell Park, Tucson, AZ
Myiarchus flycatchers are a regular identification challenge in Arizona, where three similar species overlap. I got the assurance of an experienced Arizona birder that this was a Brown-crested -- based on the large bill, relatively bright and extensive yellow on the underparts, and particularly the extensive undertail rufous running all the way to the tip. Dusky-capped has less rufous, and Ash-throated has a terminal brown strip.