Christmas Island pipistrelle

The Christmas Island pipistrelle ("Pipistrellus murrayi") was a species of bat in the Vespertilionidae family. Biologists believe the bat became extinct on 27 August 2009.
It was a small bat (it weighed ), and lived only on Christmas Island, Australia. It was thought to be the same as the "Pipistrellus tenuis", but research on the bat's baculum (a penis bone) showed that "Pipistrellus murrayi" was a different species.
Decline.
The numbers of Christmas Island Pipistrelle bats had dropped a lot in the last 20 years. It had once been seen all over the island, including in the Settlement. It went from at least 80% of its living range, and its numbers had dropped more than 90% since 1994. Research into the number of bats in January 2009, shows there were only about 20 bats left. The only known group resting place had only four bats. The last bat call was heard on 26 August 2009.
Cause of decline.
Scientists do not know why the Christmas Island Pipistrelle's numbers dropped. Several possible threats may have been:
A number of animals brought to Christmas Island could be the problem:
Saving the pipistrelle.
Early in 2009, the Australian Minister for the Environment, Peter Garrett, stopped scientists from trying to set up a captive breeding program. He said that the bats were too hard to catch, and no one knew how to keep them alive in cages. Instead, he announced a program to breed a similar bat in the Northern Territory of Australia. Scientists would learn about caring and breeding bats, then use this information to save the Christmas Island Pipistrelle. Other scientists had said this would take too long, and the bats would become extinct. Scientists believed that by June 2009 there were only four of the bats left in the world. In July 2009, the Australian Government changed its earlier decision and said that it would try to capture the last of the bats and use them to try and breed more bats in captivity. During August and September 2009 scientists searched for the remaining bats to catch them and protect them. At the end of August only one bat had been heard. Scientists tried to catch this bat, but it has not been heard from since the night of 26 August. It is now believed that the bat is extinct. This may be one of the few times that the extinction of a species in the wild can be known to the exact day. Scientists will continue to search for the bat, but there has been no signs of the bat since.