Usually bird watchers enjoy observing their feathered friends from afar with the use of binoculars, but sometimes there is a special opportunity the get to know them up close and personal. Recently, members of the Mesilla Valley Audubon Society had one such opportunity to meet Cave Swallows.
Cave Swallows are medium sized, square tailed swallows common in the US in large parts of Texas along the Rio Grande to a bit further north than Las Cruces, and Carlsbad Caverns area, and the area around Miami, Florida. Their approximate length and wingspan, depending on the subspecies, is 12-14 centimeters, or 4 ¾-5 ½ inches, and about 93 – 112 millimeters, or a bit more than 3.5 to a bit less than 4.25 inches, respectively. Cave Swallows are greyish shading to glossy gunmetal blue to almost black in places on their wings above, with some birds showing whitish splotches on their backs. In flight, their buffy orangeish-cinnamon rump patches show easily. They have glossy dark blue caps, an orange cinnamon forehead and whitish to greyish white underparts.
So far, this plumage description could also fit their more common cousin, the Cliff Swallow. However, Cave Swallows have a light buffy cinnamon colored throat, while the Cliff Swallow’s is dark and in some birds appears almost black.
In the US, historically, Cave Swallows have nested, almost exclusively, as their name suggests, in caves. Nests are in shadow near the cave entrance, but always close enough for the birds to easily see the outside. Again, as does the Cliff Swallow, they build their nests with mud balls stuck to the cliff face and line them with plant fiber and down, grass, bark and feathers. Young hatch in about 15 days and both parents feed them a diet of flying insects.
As little as 50 – 60 years ago, little was known about these birds or their habits and they were much rarer in the US that they are today. Now, thanks in part to their nesting more and more in abandoned buildings and under bridges — something they do almost exclusively in their range in Latin America—they’re expanding their breeding range. Also, over the past decade or so, large concentrations of them appear almost every year along the Mid-Atlantic coast north and in parts of the Great Lakes region in the fall. Scientists are so far not sure what is driving this.
In the Las Cruces area, a good place to see Cave Swallows is about 15 miles up I-25 at Leasburg Dam State Park in Radium Springs. There are Cliff Swallows there as well, so you can compare the two. Any bridge over flowing water is also a good place for swallow nests, so the bridges over the Rio Grande on Shalem Colony Road, at La Llorona Park on West Picacho Ave. and any other in the area, for that matter, are potential viewing sites.
A couple of weekends ago, I was part of a group of citizen scientists who trekked over to Carlsbad Caverns to provide the unskilled labor for an evening of the weekly Cave Swallow banding. We gathered at the natural entrance to the caverns ready to enter at 5 pm. There we met the two banders, who between them have over four decades of experience doing this. This banding project runs from about April to early November and is now in its 37th year. Given that the average life of a Cave Swallow is three to four years, that translates in to a whale of a lot of birds banded!
Walking down the path to the banding site, listening to instructions and setting up the net took about 30 minutes. And then, as they were zooming in and out to catch flying insects, the birds began to crash into the net. Project leader and biologist Steve West made his instructions sound so simple. All you had to do was make certain what side of the net the bird was caught in, then approach and reach into the pocket created by the impact, untangle the bird, bring it to him to take some measurements, weigh it, attach a band and let it go. Piece of cake, right?
Wrong! First, I was gob-smacked at how many times a bird that I thought collided with the net heading out to catch supper really was returning with insects for its young. Then, of course, I’d get tangled in the net while trying to get to the other side. Nets are costly, so I’d gingerly extricate myself and get on the right side. My attempts to find the pocket opening usually tangled the bird—and more often than not my fingers as well—up in the net rather than getting it out. Dave Culp, the other bander, would have to come and undo my snafu.
Then, you hold the swallow with its back in your palm and its head sticking out between your first two fingers. Sounds easy enough, but they’re first-rate contortionists and rival eels at being hard to hold still. All the while, you’re getting swallow intestinal matter falling out of the sky onto your hat and clothes. Plus, being caught in a net and disentangled from it works absolute wonders on their little digestive/excretory tracts! I now am more familiar than I ever wanted to be with the various shades and consistencies of swallow droppings.
However, the excitement of being part of this endeavor that continues to contribute invaluable data to our knowledge of Cave Swallows far outweighed, for me at least, everything else. In the two hours plus that we caught, banded, measured, weighed and released birds, we processed 150 Cave Swallows. Dave said they hadn’t done that many in years. It was a good feeling.
Holding that tiny bird in my hand and looking into its face was a humbling experience. Right there in my hand was a fellow creature and inhabitant of our common planet; our fates bound up together in ways far more complex than either of us know. For one short moment we touched each other, though; two beings who almost never do that, and I like to think that on some level the swallow knew it had nothing to fear from me. I know that I came away with a newly refreshed sense of wonder and appreciation of life.
Then, we got to sit on the path and experience at close range the nightly flight of over 100,000 Mexican free-tailed bats leaving the caverns to feed. Absolutely spectacular! But that’s another story altogether.
If you are interested in helping to continue the scientific research and assist in the banding project at Carlsbad Caverns, contact Dave Culp at email@example.com. They band weekly from spring into fall and can always use more help. No experience is required and if you don’t want to handle the birds, you can opt to be a net wrangler or help record data. You won’t get a better opportunity to see Cave Swallows – or the bat flight.
Mesilla Valley Audubon Society meetings are held monthly at the Southwest Environmental Center. Meetings are free and open to the public, with informative presentations being given after a short business meeting. They also hold monthly bird walks for beginners and regular field trips, which are usually one-day trips rather than weekend advntures such as this one to Carlsbad Caverns. In December, they conduct the Christmas Bird Count, providing data to a national project. More information is available online at new-mexico-birds.com.