New Zealand’s two native bat species are the lesser short-tailed bat and long-tailed bat.
Lesser short-tailed bats
Lesser short-tailed bats (Mystacina tuberculata) are stocky little animals with pale grey-brown fur, long pointed ears and a stumpy tail. They are the only surviving members of the Mystacinidae family of bats.
Scientists once considered short-tailed bats to be one of New Zealand’s ancient animal species. DNA evidence now suggests they are more recent arrivals. Species like the tuatara and peripatus have been present since the breakaway of New Zealand from Gondwana 85 million years ago. But Mystacinidae fossils occur in Australia, and it is likely that the ancestors of New Zealand’s short-tailed bats crossed the Tasman Sea from Australia between 16 and 28 million years ago.
Once they arrived in New Zealand, lesser short-tailed bats continued to evolve. They developed characteristics not found anywhere else in the world and have become a biological oddity. They are the only bat species that forages for food on the ground, like small rodents. Several adaptations make this possible: their robust hind legs have small claws, and their wings fold down completely and can be tucked away under side flaps of thicker skin. This allows the bat to use the elbow part of the wings as front legs.
Colonies of wingless batfly (Mystacinobia zelandica) live alongside short-tailed bats. Adult batflies and their maggots feed on bat guano (manure). When bats leave one roosting site for another there are usually a number of batflies clinging to their fur. By hitching a ride, the insects can set up colonies in new bat roosts.
Short-tailed bats are the only species of small bat which carry out lek mating (where males assemble in a special area and compete for the attention of females). During late summer, male short-tailed bats gather at strategic trees near communal roosts and attempt to attract females with prolonged singing bouts.
Lesser short-tailed bats feed on almost anything, including insects, fruit, pollen, seeds and nectar. They often scurry around on the ground like small mice, fossicking under leaf litter in search of bugs. They rely on sound and smell to locate food on the ground, but use echolocation to catch flying prey. They do not usually fly until well after dusk, and typically stay within 10 metres of the ground.
Long-tailed bats (Chalinolobus tuberculatus) are more delicate than the robust short-tailed bats. They have chocolate-brown fur, short ears, and a tail that is enclosed within a membrane stretched between their legs.
They belong to a genus of bats found commonly in Australia, Norfolk Island, New Guinea and New Caledonia. Ancestors of long-tailed bats were probably wind-blown across the Tasman Sea relatively recently (within the last 2 million years).
Although they are more common than short-tailed bats, long-tailed bats are seldom seen. They emerge from their roosts around dusk and fly off to hunt. They feed exclusively on flying insects.
Long-tailed bats form complex social groups. Research on radio-tagged bats in Fiordland’s Eglinton Valley has shown that the bats frequently switch between roosting alone and roosting with a colony, often staying only one night at the same place.