The last known Christmas Island pipistrella went missing in August 2009, and none has been located since.
This tiny bat species was endemic to Christmas Island, Australia. Scientists are puzzled by its decline, as their native habitat has remained essentially unchanged over the past 20 years.
The recent increase of Yellow Crazy Ants (Anoplolepis gracilipes) may have exacerbated the situation, but the last studied individuals appeared to be in good health. Pipistrelles typically roosted under bark and dead foliage in tropical, closed-canopy rainforest and fed on small flying insects such as moths and beetles.
Experts are confident that the Christmas Island pipistrelle is extinct because as the only microbat on the island, it is easily spotted with ultrasonic bat detectors. Long-term monitoring from these instruments showed that the tiny bats experienced a 90 percent decline between 1994 and 2006.
Although it is not confirmed, the IUCN is confident that this species is extinct.