Bats are the only land mammals endemic to New Zealand – the long tailed and lesser short tailed bats are species still surviving in the country. The third species, the greater short-tailed bat is thought to be extinct, having not been sighted since 1967. The lesser short tailed bat is currently the most endangered and is only to be found at a few places around the country. The Maori name for bats is pekapeka, and according to lore they are associated with the mythical nocturnal bird, hokioi, which foretells of death or disaster.
This ancient mammal is grey brown in colour, and weighs about 11-16 grams, with a wing span of 28-29 centimetres. Amazingly it can reach flying speeds of up to 60 kilometres an hour and sometimes flies 40 kilometres in one night. Bats use echos to hunt at night and to navigate. They send out high pitched sounds, unheard by the human ear which bounce off objects in their path. Scientists studying the bats can now detect these sounds and they can now track the bat’s movements by attaching very small transmitters to their back.
The lesser short tailed bat hunts on the ground, rather than catching its prey in the air like other bats. It feeds on fruit, nectar and insects. It uses its folded wings as front limbs, moving around much as a mouse would. The lesser short tailed bat also roosts in hollow trees, rather than caves. During the cold weather they stay there, going into hibernation, and only waking when the weather warms up.
Unfortunately these attributes have also made it an easy target for introduced predators – cats, rats, stoats and possums. Other threats have also been the impact of human settlement, with clearing areas for farmland or logging native forests, thus destroying the bat’s habitat.
It is a high priority for conservation, but excitingly a new colony was found in Fiordland in 1997. This was the only known population on the southern North Island, numbering around 300. This group was also genetically distinct from the others, and it is though that they became isolated during a glacial period on the North Island 90,000 years ago.
There was a ground breaking attempt to establish an alternative population on Kapiti Island as insurance against disaster happening to the original colony. Bats had never before been successfully transferred due to a powerful homing instinct which prevented any translocation from being successful.
They subsequently developed an unknown ear infection, and thus are now housed at Auckland Zoo to ensure their wellbeing, but research continues to overcome the problem.