Short-tailed Bat – Nationally endangered – species of highest conservation priority
The endangered short-tailed bat (M. tuberculata) is an ancient species unique to New Zealand and is found only at a few scattered sites. It is divided into three sub-species: the kauri forest short-tailed bat, found only at two sites in Northland and one on Little Barrier Island; the volcanic plateau short-tailed bat, known from Northland, the central North Island and Taranaki; and the southern short-tailed bat, found on Codfish Island and in the northwest Nelson and Fiordland areas.
They became isolated during a glacial period in the centre of the North Island, and through volcanic activity, more than 90,000 years ago. Attempts are being made to establish an insurance population in a predator-free environment. The lesser short-tailed bat is the only member of its family, Mystacinidae, known to still survive. It is listed by the Department of Conservation as a `species of highest conservation priority'. This bat is found at the northern tip of the Island.
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. Its diet consists of insects, fruit, nectar and pollen and it is thought to be an important pollinator of the Dactylanthus or woodrose, a threatened parasitic plant which grows on the roots of trees on the forest floor. 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.