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One of the most significant bird species in North America uses Carlsbad Cavern as a summer nesting home. The cave swallow, a close relative of the cliff swallow, can be seen from early February to late October (sometimes even November) nesting just inside the entrance to Carlsbad Cavern. The swallows provide entertainment for visitors by chattering, swooping, and making spectacular dives into and around the mouth of the cave.
Habitat and Range
The cave swallow is a permanent resident of Mexico. Currently it is expanding its range northward into the United States. The primary nesting sites chosen by the birds are caves, however they sometimes occupy bridges and similar structures. Unlike the cliff swallow, the cave swallows’ nest is not fully enclosed. It is shaped like a small half-cup; it is constructed of mud and plant fibers, and lined with feathers.
The colony of cave swallows at Carlsbad Cavern is probably one of the northernmost colonies of cave swallows in the United States. It is also probably the largest, no one knows for sure. A migratory species, the cave swallows usually arrive at Carlsbad Cavern in the early spring, and depart for wintering grounds by late fall.
History
Cave swallows were first found nesting in undeveloped caves in the Slaughter Canyon area in the 1930. They were rediscovered in June 1952. In 1966, three nesting pairs of cave swallows arrived at Carlsbad Cavern and made their nests just inside the entrance. Since then the population has increased to an estimated 2,000 birds. Although the colony varies in size from year to year, it is the largest known colony of this species in the United States.
Each nest usually contains from two to five eggs, which are laid in mid-May. The young birds are able to fly about 20-23 days after they have hatched. After reaching maturity the swallows appear to return to Carlsbad each summer for the rest of their lives. However, this information has not been proven, and research is ongoing.
The cave swallows share Carlsbad Cavern with the cave’s large summer Mexican free-tailed bat colony. The bats, however, roost considerably further into the cave than the swallows. The birds are daytime flyers, feeding primarily on insects. Both colonies seem to co-exist without difficulty.
A Continuing Study
In 1980, an extensive banding project was initiated by a local researcher. Its purpose is to learn more about the birds and research their winter range.
