I’ve seen these birds before but have failed to identify them, thinking they were some type of swallow. But the description in Sibley, particularly of the Western female, is conclusive. They make a gurgling chirp as the fly or, as in this case, bicker. I think these are the birds I saw last summer hanging around a saguaro, and that the birds I thought were starlings then were just the males. Nice to have that cleared up.
The Harris’s Hawk was there again today, also a beautiful Pyrrhuloxia.