NEW ZEALAND SHORT-TAILED BATS: Mystacinidae

PHYSICAL CHARACTERISTICS

New Zealand short-tailed bats are small to medium-sized bats. Their head and body length ranges from 2.3 to 3.5 inches (5.8 to 8.9 centimeters). They can weigh from 0.4 to 1.2 ounces (11 to 35 grams). As their name suggests, these bats have a short tail. The nose or snout of New Zealand short-tailed bats is relatively long and it sticks out over the lips.

These bats have unique wing membranes, the thin pieces of skin that form their wings. The parts of the wing membranes that run along the body are thick and leathery. When not flying, these bats can fold their wings beneath this thick membrane part.

Fur color on these bats is typically brown-gray or brown-black, with the tips of the hairs being white to grayish. This gives the bat a frosted look. The fur is velvety, short, and thick. New Zealand short-tail bats have relatively large ears. These bats have thick bodies with short, strong legs. The claws on their feet are pointy and sharp. The thumbs have a large claw with a talon, a sharp hooked claw, at the end and each of the toe claws also has a talon.

GEOGRAPHIC RANGE

New Zealand short-tailed bats are found on New Zealand and some of its offshore islands. New Zealand is made up of two large and many smaller islands in the southwest Pacific Ocean, east of Australia.

HABITAT

New Zealand short-tailed bats are found in moist forests, where they roost, settle or rest. These bats also forage, search, for food along low-growing shrubbery and the coastline. The greater short-tailed bat was once found on two islands but it was last sighted in 1967 and is considered extinct.

DIET

New Zealand short-tailed bats eat a broad range of foods. They are omnivores, meaning they eat both plants and animals, which is unusual in bats. Their diet includes flying and resting arthropods, animals without a backbone with jointed legs and segmented bodies, fruit, nectar, and pollen. The bat has a relationship with a rare and parasitic plant, called woodrose, or pua reinga. The flower produces nectar on the forest floor. As the bats move around eating the nectar they pollinate the plants. New Zealand short-tailed bats are the woodrose's only pollinator. Researchers have also observed New Zealand short-tailed bats sometimes feeding on birds and carrion, animals that have already been killed.

BEHAVIOR AND REPRODUCTION

New Zealand short-tailed bats are active on the ground more than any other species of bat. Like all other bats, they are nocturnal, meaning they are active at night. Several hours after dusk, they begin foraging for food by running along the ground, up trees, and along tree branches.

These bats typically roost in the hollow trees of forests. They have also been found roosting in caves, houses, and in burrows, holes that they dig in the ground. Observations have shown that these bats roost in large groups of 100 to 500 individuals during the day. They also may roost in far smaller groups, and sometimes singly. When the weather becomes cooler, the bats go into a state of inactivity called torpor, but they will come out of their roosts on warmer winter nights to forage, or search, for food.

To find food, New Zealand short-tailed bats use echolocation (eck-oh-loh-KAY-shun), a technique in which the bats detect objects by sending out high-pitched calls and then listening to the reflected sound. They also find prey, animals hunted for food, by listening for movements and using their sense of smell. They commonly hunt prey on the forest floor, often forming burrows or holes under leaf litter in the ground to forage for food. When they tuck their wings away, these bats use the front arms like front legs, which helps them move along the ground.

Female New Zealand short-tailed bats give birth to one offspring once a year. The timing of mating and births appears to vary according to their location. Limited observations of the greater New Zealand short-tailed bat suggest that a single young may be born from spring to autumn.

NEW ZEALAND SHORT-TAILED BATS AND PEOPLE

People have caused a population decline in the New Zealand short-tailed bats, primarily through introducing predators, animals that hunt the bats for food, and destroying the bats' natural habitat. In stories the Maori (MAH-oo-ree), the original settlers of New Zealand, associate bats with a mythical, night-flying bird that foreshadows death or disaster.

The lesser short-tailed bats play an important role in the continued life of plants in New Zealand. As they feed on nectar and other plant material, they move from plant to plant and spread pollen, the fine grains that contain the male reproductive cells of seed plants. They are the only pollinators of the woodrose, an endangered and unique flower. These bats also are predators on insects that people may consider pests.

RAT TROUBLE:

Before humans arrived on New Zealand there were no predators of bats and they were free to roam on the ground. When the Maori, the first settlers of New Zealand, arrived they brought Polynesian rats with them. Polynesian rats were predators of New Zealand bats and they quickly spread. By the early 1800s, when European settlers arrived in New Zealand, the greater short-tailed bat had been devastated. It was extinct over 98 percent of its habitat and only survived on two small rat-free islands. The lesser short-tailed bat was not affected as badly.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists the lesser New Zealand short-tailed bat as Vulnerable, facing a high risk of extinction, and greater New Zealand short-tailed bat as Extinct, no longer existing. The lesser New Zealand short-tailed bat is known to be present on several islands. Populations have declined to about ten populations that may contain only a few thousand individuals.

LESSER NEW ZEALAND SHORT-TAILED BAT (Mystacina tuberculata): SPECIES ACCOUNT

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 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. ∎

FOR MORE INFORMATION

Books:

Fenton, M. Brock. Bats. New York: Checkmark Press, 2001.

Fenton, M. Brock. The Bat: Wings in the Night Sky. Buffalo, NY: Firefly Books, 1998.

Nowak, Ronald M. "New Zealand Short-tailed bats." Walker's Mammals of the World 5.1 Online. Baltimore: Johns Hopkins University Press, 1997. http://www.press.jhu.edu/books/walkers_mammals_of_the_world/chiroptera/chiroptera.mystacinidae.mystacina.html (accessed on July 5, 2004).

Richardson, Phil. Bats. London: Whittet Books, 1985.

Ruff, Sue, and Don E. Wilson. Bats. New York: Benchmark Books, 2001.

Schober, Wilfried, and Eckard Grimmberger. The Bats of Europe and North America. Neptune City, NJ: T.F.H. Publications, Inc., 1997.

Periodicals:

Flannery, Tim. "A Lost Menagerie." Natural History (November 2001): 66.

"Hunt for the Short Tailed Bat." Wairarapa Times (February 26, 2000).

Jones, G., P. I. Webb, J. A. Sedgeley, and C. F. O'Donnell. "Mysterious Mystacina: How the New Zealand Short-Tailed Bat (Mystacina tuberculata) Locates Insect Prey." Journal of Experimental Biology (December 2003): 4209–4216.

Web sites:

Daniel, Mike. "New Zealand's Unique Burrowing Bats Are Endangered." Bat Conservation International, Inc. http://www.batcon.org/batsmag/v2n3-1.html (accessed on July 5, 2004).

"New Zealand Short-tailed bats." BBC Science and Nature. http://www.bbc.co.uk/nature/wildfacts/factfiles/668.shtml (accessed on July 5, 2004).

Weinstein, B., and P. Myers. "Family Mystacinidae (New Zealand Short-tailed Bats)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Mystacinidae.html (accessed on July 5, 2004).