January 2009, Volume 7, Issue 1

Imminent Extinction

Without immediate and powerful action, the Christmas Island pipistrelle, found only on a small island off the Australian coast, will likely go extinct this year – a victim mostly of introduced predators. Scientists and conservationists are proposing a 10-year captive-breeding program to save this little bat. They need your help to encourage government action.
With only a few dozen surviving individuals, the Christmas Island pipistrelle (Pipistrellus murrayi) is listed by IUCN, the world conservation union, as “Critically Endangered.”
Australian conservationist Greg Richards, a member of BCI’s Science Advisory Board, says a survey 25 years ago, for the pipistrelle to be very common throughout the entire 52-square-mile (135-square-kilometer) island. Ten years later, in 1994, it had disappeared entirely from the northeast and appeared less numerous islandwide. That was the beginning of the species’ breathtaking collapse.
Richards said repeated surveys consistently found a rapidly declining population, until by 2006, the bats were found at only 8 of 44 monitoring sites. Richards and biologist Lindy Lumsden visited in January 2009. “The news is very distressing,” he said. “Lindy checked old roosts and found just one little colony of four bats in the only roost occupied, and these were probably females feeding young.” The roost was home to more than 50 bats in 2006.
He said some males undoubtedly survive and are probably roosting individually, and “there may be the odd colony in areas that haven’t been explored as yet.” But, Richards concluded, “there may only about 30, at best 50, of these bats now left in the world!”
The pipistrelle traditionally had few natural predators on the island. Then Asian wolf snakes were inadvertently introduced in 1987 by visiting ships. The snakes became incredibly common as they spread across Christmas Island. The snakes could climb trees and catch pipistrelles roosting in tree hollows, where a single entrance left them with no escape. The bats eventually responded by shifting their main roosting preference to underneath loose, flaking bark on dead trees. This strategy would have given them a hiding place with several escape routes.
A few years later, the island population of giant centipedes exploded and were noticed everywhere on the Island. This huge invertebrate is known to eat bats in South America and almost certainly became a major bat predator on Christmas Island, where pipistrelles were finally escaping the wolf snakes.
This rogues gallery of island threats also include the voracious “yellow crazy ant” that was introduced early in the 20th century. They form huge colonies throughout the island and forage in trees. They are known to kill red crabs the size of a man’s hand and almost certainly have killed pipistrelles. The crazy ants also removed a lot of bat prey, especially small moths and beetles in the larval stage, adding starvation to predation. Efforts to eradicate the ants with insecticide quite possibly wiped out still more of the bats’ prey.
Richards and his colleagues say there is no time left for more investigations – immediate action is required. “We feel that the only thing left to do is to take the last few bats out of their current perilous situation and establish a captive breeding colony, which will require a large injection of funds and at least a 10-year commitment. Considering the low numbers that such a program would start with, they predict it would be 10 years before pipistrelles could be re-introduced to the wild.”
Richards is asking the Australian Government to support the captive breeding plan. He asks all friends of bats to express their concern for this desperately endangered bat to the Minister of the Environment.
If decisive action is not taken soon, the Christmas Island pipistrelle will disappear forever.

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