WASHINGTON (CN) - Two birds, two snails and a bat in American Samoa have been proposed for listing as endangered under the Endangered Species Act (ESA). The five species are affected by habitat loss, invasive species and climate change. The U.S. Fish and Wildlife Service proposed to list the friendly ground dove, two endemic snails with no common names, the Pacific sheath-tailed bat and the mao, a large endemic bird, in the action published Tuesday.
American Samoa, a territory of the United States consisting of five islands and two atolls, is part of the Samoan Islands chain in the South Pacific. Two of the proposed species, the mao and the sheath-tailed bat, are believed to be locally extinct in American Samoa but still occur in small populations on other islands in the chain, the agency said.
Of the other proposed species, the friendly ground dove, occurs in other island groups in Polynesia, so the Service has proposed the distinct population segment of the birds that occurs in American Samoa for listing. The two land snails are found only in American Samoa, the agency said.
The listing proposal was spurred by a court settlement between the Service and the Center for Biological Diversity (CBD) and its allies that mandates listing determinations for hundreds of species be completed over a six year period.
"American Samoa is home to incredible wildlife found nowhere else on Earth," Sarah Uhlemann, CBD international program director, said. "But many of its native animals and plants are threatened by habitat destruction and invasive species. Endangered Species Act protection gives these beleaguered island species real hope."
All of the proposed species are impacted by the loss of habitat due to deforestation by the conversion of forested areas to agriculture, and by the introduction of invasive plant and animal species. Hurricanes further exacerbate the threats by destroying areas of closed forest and creating openings where invasive species can get a foothold and crowd out native species.
The flora native to the Samoan archipelago consists of around 550 taxonomic groups, of which about 30 percent are endemic species that occur only in those islands. "An additional 250 plant species have been intentionally or accidentally introduced and have become naturalized with 20 or more of these considered invasive or potentially invasive in American Samoa," the agency said.
Non-native animals also contribute to habitat destruction and predation on the proposed species. Three species of rats have been introduced to the islands and they are known predators of snails and bird eggs. The island birds, such as the moa and the ground dove, evolved without those predators and now lack behavioral defenses against them. Invasive rosy wolf snails and flatworms also prey on the endemic snail species.
Introduced pigs and cattle trample vegetation and contribute to erosion. "Feral pigs cause multiple negative impacts to island ecosystems including the destruction of vegetation, spread of invasive nonnative plant species, and increased soil erosion," the agency said. Feral cattle also eat tree seedlings and saplings, which interferes with forest regeneration, and opens the forest to invasion by nonnative species.
"These species in American Samoa are facing tremendous challenges with shrinking habitat and the onslaught of invasive species," Kristi Young, the Service's acting field supervisor for the Pacific Islands Fish and Wildlife Office, said. "The Service looks forward to continuing to work with the local government, partners, and the people of American Samoa to conserve part of what makes these islands so special."
Comments on the listing proposal are due Dec. 14. The Service plans to propose critical habitat at a later time, according to the agency.
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