Two islands in Alaska's Aleutian Chain, both of which were once caribou-free, are now the subject of an effort to prevent the species' spread from Adak -- already home to thousands of caribou -- to nearby Kagalaska.
According to a Monday announcement from the U.S. Fish and Wildlife Service, the federal agency is now accepting public comments on a recently completed draft of Environmental Assessment of Caribou Control on Kagalaska, Alaska Maritime National Wildlife Refuge, in an effort to control the "invasive caribou."
The "proposed action," as described by U.S. Fish and Wildlife, would send AMNWR staff, volunteers or contractors to the island of Kagalaska, adjacent to Adak, to shoot caribou they spot as preventative measure to keep the species -- which isn't native to the region -- from forming a herd.
AMNWR manager Steve Delehanty said a couple of caribou, which he describes as being "pretty good swimmers," swim to Kagalaska every year, on a short, 8-mile journey through a narrow passage of the Bering Sea. The route they take is only a half of a mile wide at its least narrow portion.
The environmental assessment estimates zero to 10 caribou living on Kagalaska, but last year only three were spotted. According to Delehanty, eliminating the caribou would only be a "preventative measure" to keep the species from disrupting the island's natural habitat.
"If we do nothing, they could build up a population on the island and damage the island, and they could use it has a stepping stone to get to the next island," said Delehanty.
Caribou were brought to the region in the 1950s and introduced to Adak while the U.S. military occupied the island. A press release from Fish and Wildlife said the species helped provide "recreational opportunities for military personnel."
In 1997, when the base shut down, Adak's human population shrank while the caribou population thrived. Since then, Adak has had relatively liberal hunting laws -- there is currently no closed season -- which helps with caribou population control, said Delehanty.
But even with a year-round hunting season, the island's 283 residents are significantly outnumbered by the estimated 2,690 caribou Delehanty said were counted in 2012.
"When the species is brought to an island with good, healthy conditions, they thrive, build up population and eat themselves out of house and home," said Delehanty.
Delehanty used St. Matthew Island in the Bering Sea as a prime example.
In 1944, reindeer were introduced to the area. The reindeer were managed by the local communities and used as a food resource.
"They were brought there with good intention, but when human activity ceased, the (reindeer) population exploded," said Delehanty.
David Klein, who Delehanty said studied the St. Matthew reindeer "extensively," published his findings (PDF) in 1968, in The Journal of Wildlife Management. Klein found that from 1944 to the summer of 1963 the caribou population went from 29 to 6,000, but were unable to sustain the population.
"In a hard winter there was a massive die-off, and that is a pattern that has repeated on other islands," said Delehanty in a phone interview. As he describes the chain of events that unraveled on the remote island, St. Matthew's reindeer population went from zero, to a couple dozen, to hundreds, to thousands and back to zero -- leaving long-lasting marks in the decades since their deaths.
"It caused long-term damage," said Delehanty. "And we don't want that in Kagalaska. We don't want to disrupt the natural habitat" -- or, as Fish and Wildlife puts it, they hope to "maintain its natural character."
Public comments on the plan can be emailed to FW7_Kagalaska@fws.gov.