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Barn Swallows in Battery Pensacola Like the storied birds of San Juan Capistrano, barn swallows come to Gulf Islands National Seashore every spring to nest in Battery Pensacola, the 12-inch gun battery built within the walls of old Fort Pickens in 1898. Park rangers and volunteers then close the battery to the public to give the birds a secure area to build nests and raise their young. Fabulous Fliers Swallows have long, powerful wings and small, weak feet, an excellent example of the evolutionary effects of use and disuse. Their graceful, darting flights are a delight to the eye. Swallows feed in flight, often low to the ground, where they find small flying insects, mainly flies, ants, weevils and beetles. These gentle and harmless creatures are very sociable, and seem to show a playful spirit in flight and in gathering feathers for their nests. However, they will aggressively defend nesting areas once eggs hatch until the young fledge. Migration Barn swallows range from Alaska and Canada in summer, to southern Brazil, Paraguay, Bolivia, Peru, and Argentina in winter. They breed across the whole of the southern United States, although only fairly recently in Florida. Nesting in Florida seems to have followed the "human migration" in the 1920s, when the state's population began its rapid rise. Nests are bowl-shaped hemispheres, made of mud pellets mixed with straw and grass, lined with feathers. Their fondness for buildings makes them one of the most "domesticated" of wild birds. Where human structures do not exist, barn swallows will build on cave walls or cliffs. Both sexes work on the nest together. Working as much as 14 hours per day, a pair of barn swallows may spend 8 to 12 days to build a new nest. No wonderthey prefer reusing or repairing old nests when possible. Reproduction Barn swallow nests usually hold four or five eggs. Egg markings vary widely. The base color is white, with reddish brown to darker brown, spots, sometimes with pale lilac underlying. Incubation averages 15 days, and is shared by both parents. Parents change places at intervals of 15 to 30 minutes, although the female sleeps on the nest at night while the male perchs nearby. Farmers' Friends The barn swallow's habit of nesting in barns, combined with a diet consisting almost entirely of insects, makes them very useful to farmers. Swallows are known to follow farmers plowing fields, eating the insects stirred up. They are also seen among cattle and sheep for the same reason. They are so effective at eating harmful insects that there have been cases of vegetation being saved on farms with breeding colonies, while neighboring farms without swallows were almost denuded of plant life. Swallow Song The notes of barn swallows have been described as, "kvik-kvik, wit-wit," in short, delicate syllables. They are among the most melodious of birds, with one of the longest song seasons. Barn swallows sing from their arrival in April, throughout the summer, from early morning until nightfall. Endangered Species? Barn swallows are not listed as threatened or endangered, but their numbers have declined over the years. A threat to their survival is inclement spring weather. Cold spells drive insects to cover, depriving the birds of food. Old birds, as well as young birds in nests, die from hunger and cold. Other threats come from house wrens, phoebes, and English sparrows, which will occasionally take over swallows' nests. Some predators, including cats and even large fish and bullfrogs, can catch the birds as they skim low over ponds and fields. The Human Factor As with many species, the decline in barn swallow populations has a human factor. Changes in farming practices, including closed barns and the shrinking numbers of farms, reduce nesting places. Even where nesting occurs, increased human activity can disturb incubation patterns. This is the primary reason for closing Battery Pensacola during nesting season. Sadly, the most dramatic decline in barn swallows occurred in the 1880s, when thousands were killed to make ornaments for women's hats. This bird aroused the editor of Forest and Stream magazine, George Bird Grinnell, to write the editorial about the waste of bird-life for hats which led to the founding of the first Audubon Society in 1886. Of Birds and Batteries The swallows' nesting in an old Army gun battery is a splendid example of the complexity of resources found at Gulf Islands National Seashore. The park is a recreation area, an historic treasure, and a nature preserve, including designated wilderness areas. These three values could find no better expression than in closing a part of one historic structure for the temporary use of our feathered friends. With your help, we can pass these values on to future generations. |
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Last Updated:
1/6/03
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