29 January 2007

Kapiti bats breed, but pups stillborn

Rare short-tailed bats transferred to Kapiti Island in a bid to save a threatened Tararua Forest Park colony have bred, but sadly the two pups produced were stillborn.

While disappointed that the pups died, the Department of Conservation says the fact that bats from a ground-breaking translocation attempted to breed so young adds to the important knowledge known about bats’ basic biology.

“This shows that the small numbers of bats on Kapiti, fewer than seven mature animals in the wild, were able to interact socially and mate successfully,” DOC technical support manager Colin Miskelly said.

“The age of first breeding of short-tailed bats was not known until now, but it was expected to be three to four years old. The Kapiti bats were just two years old and it’s likely that they mated in the wild before being returned to captivity. This result has given us further confidence that the translocation of bats can be successful, provided the cause of ear lesions detected on the Kapiti Island bats can be determined and resolved.”

The bats were taken to the island in 2005 and 2006 as part of an ambitious plan by DOC to save a threatened and isolated colony of short-tailed bats in the Tararua Forest Park. Pregnant bats from the colony were taken to the Pukaha Mount Bruce National Wildlife Centre to give birth in captivity. The females were then returned to Tararua Forest Park, and the pups taken to Kapiti Island and kept in captivity before their release.

While DOC succeeded in developing techniques to overcome the strong homing instinct of the bats, the project suffered setbacks, including the deaths of pups in captivity at Pukaha Mount Bruce and an ear infection contracted by the bats in the wild on Kapiti Island, affecting their ability to echo-locate. When exhaustive tests failed to identify the cause of the infection, DOC abandoned plans for a third transfer this summer and have decided to keep the bats in captivity permanently.

The bats are now being held in an aviary on Kapiti Island where the two stillborn pups were discovered on December 30. Autopsies undertaken at Massey University have failed to identify the cause of their deaths.

Dr Miskelly said while there were always risks associated with this cutting edge type of species work, much had been learned about translocation of bats as a result of this project. The lessons learnt would benefit other bat translocations both in New Zealand and overseas.

“We are confident that the potential and actual benefits justified the risks in this case.”

ENDS

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