Bumping along a dusty ranch road at the base of the Glass Mountains in west Texas, a fellow grad student and I were intent on finding grasshoppers for a research project. When we stopped, I noticed a large group of swallows swirling around an opening on the side of a mountain. We climbed up the slope and found a sinkhole about feet deep. Cave Swallows flew all around in what we soon realized was an important nesting site, a colony of birds. Grasshoppers quickly took backstage as we watched the swallows spiraling down and feeding nestlings.
In a few days, I returned to band some of the birds. Swallows are small songbirds known for their fast, smooth flight. Of the eight species that breed in North America, the Cave Swallow has the most limited distribution. One population breeds in the Caribbean and south Florida, and the other occurs in Texas, north-central Mexico, and southern New Mexico. My efforts to learn more started at that Texas sinkhole and continue to this day.
In the fall of , I moved back to my home state of New Mexico and spent the next couple of years, off and on, observing Cave Swallows at the mouth of the large entrance to world-famous Carlsbad Cavern in the national park of the same name.
I had seen the birds in New Mexico before, but for a long time, the only way to find them was to make a long, hot hike into the backcountry of the park to a few obscure caves. Fortunately that changed in , when three pairs showed up at the cavern. The cave, which is visited by hundreds of thousands of people each year, suddenly became one of the easiest places to see the bird.
For a while, going to the entrance between March and October was one of the only sure ways to add the Cave Swallow to your life list.
