Found at the mouth of Florida Canyon, Pima Co., AZ. April 28, 2019.
It was giving a call similar to the "chi-bik" of a Least Flycatcher, but it was rougher, lower pitched, and louder.
The 'vest' made me think WWPE upon first sight, but the eye-ring, strong yellow, and short bill made me look at Empids. The closest fit is Yellow-bellied, but range maps do not extend to AZ and there are very few eBird occurrences for AZ.
Any thoughts?