The Cliff Swallows

of

Miller Springs

Prepared by

Stan Casto and Amy Wright

Department of Biology

University of Mary Hardin-Baylor

January 1992

Cliff Swallows once nested at many natural sites throughout Central Texas. Today, however, most swallow colonies are associated with man-made structures such as bridges, overpasses, and culverts. The two nesting sites at Miller Springs represent relatively undisturbed locations where Cliff Swallows can be observed in their natural habitat. One of these nesting sites is located along the Leon River whereas a second site is found in Cox's Canyon. The locations of the "Riverside Colony" and "Cox's Bluff Colony" are indicated on the map.

(map under construction)

Cliff Swallows do not nest every year in the park. Their jug-shaped, mud nests, however, persist for several years and can be easily observed on the cliff face. In an effort to reduce disturbance by humans, rappelling from the riverside bluff and Cox's bluff is prohibited during the breeding season of the swallows.

The Miller Springs Alliance encourages you to spend a few relaxing hours enjoying the Cliff Swallows in their natural setting. The information provided below will hopefully serve as an aid to your study of the natural history of these interesting birds.

Feeding Habits: Cliff Swallows feed while flying and often dive close to the ground to catch insects such as beetles, chinch bugs, flying ants, wasps, grasshoppers, dragonflies, mosquitoes, and spiders. They are also known to eat the fruit of junipers.

Construction of Nests: Cliff Swallows require a vertical, protected surface on which to construct their nests. A supply of the appropriate consistency of mud is also a prerequisite for nesting. East next is built by a pair of swallows and consists primarily of mud pellets with perhaps a sparse lining of grass, hair, or a few feathers. While gathering mud in their bills, the swallows perform an interesting behavior in which they elevate their tails and hold their rapidly fluttering wings high above their bodies. Although nests from a previous year may be re-used, Cliff Swallows tend to switch nesting sites from one year to the next. The completed nest is 5-6 inches long with a neck that points slightly downward to a narrow, circular entrance. The nests are usually built close together and often touch. Colonies may consist of only a few dozen to as many as 2,000-3,000 nests.

(sketch under construction)

Eggs and Young: The breeding season extends from late March to early August. The majority of pairs raise a single brood per season. The 4-5 eggs are white with brown dots or blotches concentrated near the larger end. The eggs, which are laid at daily intervals, are incubated for about 15 days. Both parents feed the nestlings who generally fledge about 23 days after hatching. The juvenile birds are similar to the adults except duller in color.

References:

• Bent, A.C. 1963. Life Histories of North American Flycatchers, Larks, Swallows, and Their Allies. Dover Pub.
• Harrison, Colin. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins.
• Oberholser, H.C. 1974. The Bird Life of Texas. University of Texas Press.
• Terres, John K. 1982. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knopf.
• Turner, Angela K. 1989. Swallows and Martins: An Identification Guide and Handbook. Houghton-Mifflin.

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Last updated: April 05, 2000