Excerpts from Jim Conrad's
Naturalist Newsletter

from the November 22, 2009 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO; limestone bedrock, elevation ~39m (~128ft), ~N20.676°, ~W88.569°
SWALLOW IN MY ROOM
When I first moved into the storage room adjoining a lovely old church atop a hill (which surely is a ruin mound) I found myself with several bat and swallow roommates. Since I leave the door open at night the bats are still with me, but the swallows didn't like my locking the door during the day. Eventually they moved out -- but not before I got a picture of one circling just beneath my ceiling, shown below:

Ridgway's Rough-winged Swallow, STELGIDOPTERYX RIDGWAYI

In the Yucatan we have three fast-flying, dusky-chested swallow-type bird species so similar that I've pretty much given up trying to distinguish them: The Ridgway's Rough-winged and Northern Rough-wing Swallows, and the Gray-breasted Martin. The last two species are widely distributed migrants, the swallow here only during the winter and the martin only during the summer. The Ridgway's Rough-winged Swallow is endemic, found only in the Yucatan and a bit of adjoining Mexico, plus Belize and northern Guatemala. "It'd be neat if this turned out to be a Ridgway's," I thought to myself as I snapped the picture.

Once I got the image onto my laptop screen, by golly it did turn out to be a Ridgway's Rough-winged Swallow, STELGIDOPTERYX RIDGWAYI. Some experts lump Ridgway's with the Northern Rough-wing but Howell in his wonderful "A Guide to The Birds of Mexico and Northern Central America" separates them, and that's fine with me.

Two field marks indicate that this is a Ridgway's. Most importantly, where the white part of the body extends into the fanned-out black tail the feathers covering the very tip of body are black -- the "distal undertail coverts" are black, as the experts say. In the other species the distal undertail coverts are white. Second, right in front of the eye you can barely see a tiny pale spot. Ridgway's has that, the other species don't.

Howell says that Ridgway's nests in "cavities in caves, limestone sinks, ruins." Well, we have Chichén Itzá's standing ruins all around us and I'll bet Ridgway's Rough-winged Swallows are in and out of those every day. The church next to my room certainly is home to its share, as the guys in charge of keeping the building clean know too well.