FWS Considers Import Ban on Snakes to Protect Native Birds

Anhinga. Photo: USFWS

To prevent further introductions of invasive species, the U.S. Fish and Wildlife Service is considering adding a number of constrictor snake species to the injurious wildlife list under the Lacey Act, making it unlawful to import, transport, buy, or sell any species of the python, boa, or anaconda genera. American Bird Conservancy submitted a letter in support of this proposal saying, “…this action is necessary to prevent the further introduction of these aggressive, invasive predators that are known to be highly adaptable to new environments and consume a wide variety of prey including various native mammal, amphibian, lizard, and bird species.”

Long-lived snake species with high reproductive output, such as the Burmese python, have great potential to proliferate rapidly, and quickly expand from their place of introduction. They represent a potential ecological and economic disaster with the capacity to quickly overtake even the most far-reaching eradication efforts to protect endangered species. Recently released climate maps by the U.S. Geological Survey indicate that the Burmese python could find extensive suitable habitat, comparable to the size of its native range in Asia, in the southern one-third of the lower 48 States. Should these snakes become more widely established they will further exacerbate the threat they already pose to the health and abundance of many bird species.

According to a recent study of the stomach and lower gastro-intestinal tracts of 56 Burmese pythons captured in or adjacent to Everglades National Park, 50 were found to have eaten many bird species, including Anhinga, American Coot, Pied-billed Grebe, Limpkin, King Rail, Purple Gallinule, Great Blue Heron, White Ibis, Red-winged Blackbird, Virginia Rail, Great Egret, Magnificent Frigatebird, Clapper Rail, and House Wren. The White Ibis and Limpkin are Florida Species of Conservation Concern, and the King Rail and the Clapper Rail are on the ABC/Audubon WatchList of species in need of immediate conservation attention.

Though not covered by the proposed amendment to the Lacey Act, the brown tree snake serves as a constant reminder of the threat of introduced snakes and other predators. The snake was accidentally introduced to Guam in the 1950s from its native range of New Guinea and Australia. It soon devastated the island's bird life, which had evolved in a snake-free habitat, and consequently lacked the protective behaviors or adaptations of other birds, making them easy prey. Taking eggs and birds alike, the brown tree snake has caused the extirpation of nine of the eleven native land bird species on Guam, including the endemic Rufous Fantail and Bridled White-eye, and the Guam Rail, which is now extinct in the wild. Its predation of native birds has been so complete that the brown tree snake now survives by feeding almost exclusively on the island’s lizard species.