DOC targets rats to help save struggling bats
The Department of Conservation is going in to bat for a critically endangered mammal species in Fiordland.
A low count of long-tailed bats in the Kepler Mountains is prompting DOC to design and undertake rat control to protect the rare species.
The rat control will emulate that undertaken by DOC in the Eglington Valley, the only other known long-tailed bat habitat in Fiordland.
There was excitement surrounding the discovery of the long-tailed bat colony near the Kepler track in December 2011, with DOC staff estimating the population was close to 70.
But in November and December DOC caught and tagged only 46 long-tailed bats in the Kepler Mountains.
DOC Fiordland biodiversity ranger Hannah Edmonds said after spending four weeks in the Kepler area, the team had hoped to find double that number. Long and short-tailed bats are the country's only native land mammals, and both are endangered.
Bats were targeted by rats and were particularly vulnerable at their roost sites, Ms Edmonds said.
There was a rat control programme in the Eglinton Valley and the number of long-tailed bats was 80 to 120, she said.
"Maternity roosting areas need to be found in the Kepler area this summer so that rat control can be put in place to protect maternity roosts from rats during an anticipated plague year."
DOC was planning rat control in the Kepler area to protect the long-tailed bat colony, she said.
The low count was made even more concerning because of a significant beech mast (nut) event set to produce an explosion in rat numbers this winter.
"Unlike birds, once the bats are gone from the Kepler Mountains we are unlikely to ever see a return of either species through either self reintroduction or by a planned translocation, as there have been no successful translocations of bats," she said.
Ms Edmonds also said short-tailed bats had been detected on automatic bat recorders in the Kepler Mountains, but their presence still needed to be officially confirmed.
A colony of short-tailed bats in the Eglinton Valley is one of only two known populations of short-tailed bats on mainland South Island. The other was Oparara Basin in the northwest Nelson region and there are also colonies on Codfish and Little Barrier Islands.
Further research would be required to confirm if short-tailed bats were present in the Kepler Mountains, Ms Edmonds said.
Long-tailed bats were once common in Christchurch, Dunedin and Invercargill but are now rare because of rats and forest clearance. Chestnut brown in colour, they weigh 8g to 11g, smaller than short-tailed bats. Can fly at 60kmh and have a very large home range of 100sq km. Feed on small moths, mosquitoes and beetles. A Maori proverb urges travellers to hurry if they see a long-tailed bat, or pekapeka, because it foreshadows the arrival of a hokioi – possibly the Haast's Eagle – a bird associated with death. Source: Department of Conservation
The Southland Times