New Zealand Short-Tailed Bats: Mystacinidae

Physical characteristics: Lesser New Zealand short-tailed bats are a relatively small species of bat. The length of their body and head together ranges from 2.3 to 2.6 inches (5.8 to 6.6 centimeters). The wingspan of these bats is 11 to 11.4 inches (28 to 29 centimeters). There are three subspecies of the lesser New Zealand short-tailed bat, and all vary in size. The bats that live in the south are larger than those that live in the north.

Also called a northern short-tailed bat and the New Zealand long-eared bat, these bats have fur that is short, thick, and velvet-like. Their fur is typically brown-gray or dark brown in color. The hairs have white on the tips, which gives these bats a frosted appearance. These The lesser New Zealand short-tailed bat is the only pollinator of the woodrose, an endangered and unique flower in New Zealand. (Illustration by Barbara Duperron. Reproduced by permission.) bats have large, simple ears. The thumbs and each of the toe claws have a talon at the end.

Geographic range: Lesser New Zealand short-tailed bats live on New Zealand and some of its offshore islands. Fossil evidence suggests that these bats once lived on all the islands of New Zealand. In recent years, populations of these bats decreased to only an estimated ten locations on several islands.

Habitat: Lesser New Zealand short-tailed bats are found primarily in the moist, native forests of New Zealand. They often roost in the hollows of trees but have also been found roosting in houses, caves, and burrows. They have been observed foraging for food and flying along coastlines and in grassy areas with low shrubbery.

Diet: Lesser New Zealand short-tailed bats have a wide range of food options. They eat both flying and non-flying arthropods, nectar, pollen, fruit, and other plant materials. Observations have also spotted these bats eating both young and adult birds, along with the meat of animals that are already dead.

Behavior and reproduction: Unlike most bats, the lesser New Zealand short-tailed bat spends much of its time scurrying about on the ground, up trees, and along branches. Their ability to fold their wings up prevents them from injury as they move about. When they fold up their wings the bats can walk on their hind legs and use their front arms. These bats still fly but it is not known how much they use flight.

These bats roost in large groups of 100 to 150 individuals or more, and also to roost in small groups. They emerge several hours after dark to search for food. These bats chew out cavities, holes, and tunnels to use as roosts.

Researchers are still working to understand these bats' mating and reproduction. The bats have a breeding season in which males and females separate. At dark, males travel to the hollows in trees where they call out a high-pitched call or song. Females visit and mate with the males each evening, before they begin foraging for food. Females give birth to one offspring each year. In the northern populations the young are born in the summer, January and December; in the southern populations they are born later, April to May. Newborn bats are furless and born with their eyes open. They are able to fly in four to six weeks, and reach adult size at eight to twelve weeks.

Lesser New Zealand short-tailed bats and people: Because Lesser New Zealand short-tailed bats eat pollen, nectar, and other plant materials, they play a significant role in the continued survival of many plant species. People have had a significant impact in the decline of the population by introducing bat predators, such as Polynesian rats. The introduction of other species has also indirectly harmed the bat population. The Australian brush-tailed possum was introduced to start a fur industry, and one method of killing the possum is with cyanide poison that often contains added fruit smells to lure the animal. Since the lesser short-tailed bat spends a great deal of time on the forest floor, this poison can attract the bats. It is unknown how many bats have been killed by this method. People have also caused the decline of these bats by clearing the forests where these bats live.

Conservation status: Lesser New Zealand short-tailed bats are protected by law and listed by the Department of Conservation of New Zealand as a species of highest conservation priority. The New Zealand Red Data Books lists this species as Vulnerable to Endangered, facing a very high risk of extinction in the wild in the near future. The IUCN lists the lesser short-tailed bat as Vulnerable. ∎