Kingbirds’ Departure

It’s the privilege of the immigrant to sniff at the misconceptions of those benighted outlanders who haven’t taken the same step yet: as an eager but adoptive Arizonan, I shake my head and cluck my tongue at those who believe that we here in the Sonora Desert live in an endless spring.

I suppose we do, comparatively–but even here there are still unmistakable signs of winter, and they bear down on us as early as mid-September.

It may be more subtle than the late summer cold fronts and warbler waves of the east and midwest, but the dribbling away of Western Kingbirds this time of year is as sure a sign of a cooler season ahead as the arrival of juncos on a crisp morning in New Jersey or Nebraska.

Ebird tells the story. Check just about any southeast Arizona site for this species, and you’ll find abundant reports of large numbers in August–and just stragglers by now. Then have a look at the data from Sonora: aha, that’s where they all are!

Every one of the three Western Kingbirds I saw today around Tucson was a fork-tailed individual, and thus an adult; this summer’s birds have evenly squared tails, not yet having endured the sequential molt that gives their senior’s autumn gaps and notches. Birds like this, their clear gray breasts and satiny black tails notwithstanding, are responsible for many of the late-season reports of Tropical Kingbird here, and another reminder that it’s at least as important to think about intraspecific seasonal variation as it is about “field marks.”

For more about the yellow-bellied kingbirds of southeast Arizona, take a look at this week’s IBIS.