New Zealand Short-tailed bats (pekapeka)

Bats are the only mammals capable of sustained flight. Of 951 species in the world today , just two species occur in New Zealand – the lesser short-tailed bat Mystacina tuberculata and the long-tailed bat Chalinolobus. (We once also had the greater short-tailed bat but this is now thought to be extinct, through predation by kiore and ship rats). Referred to by Maori as pekapeka, bats are New Zealand’s only endemic land mammals.

The long-tailed bat is the more common species, widely distributed in the North Island and about half of the South Island including some islands. It is the bat most likely to be seen by the general public because its habitat can be found from sea level through to the tree line in the mountain ranges. It usually roosts along the forest edge and feeds along forest margins. It has been seen roosting in houses, farm buildings and mountain huts.

Short-tailed bat
The endangered lesser short-tailed bat 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. 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”.

Brian Lloyd measuring a Tararua short-tailed bat during the translocation.

Brian Lloyd, the Department of Conservation specialist in native bat conservation, states that “both of New Zealand’s remaining bat species have suffered massive declines since humans arrived in New Zealand and are now considered endangered. The primary threat to both species has been and remains forest destruction by humans. For short-tailed bats selective logging is likely to be as devastating to the species as clear-felling. A longer term threat to both species is degradation of forests by pests and possible subsequent failure in succession of mature old growth forest. Long-tailed bats are vulnerable to predation in their roosts by mustelids and rodents. Evidence on lesser short-tailed bat’s vulnerability to predation is contradictory. Prior to European settlement in the nineteenth century, short-tailed bats were widespread throughout the almost continuous tract of old-growth forest that covered central North Island. Extensive deforestation during the period 1890 to 1980 restricted bat populations to remnant patches of forest. Previously abundant throughout New Zealand, lesser short-tailed bats are now endangered, with less than 50 000 individuals in thirteen known populations. Most are in the central North Island where seven populations contain a total of about 40,000 bats. Outside of central North Island there are four small isolated populations on the mainland and two sizeable populations on offshore islands. Mainland populations outside of central North Island each contain only a few hundred bats and are vulnerable to extinction”.

The Tararua Forest Park short-tailed bats
A colony of around 300 short-tailed bats was found in the Waiohine Valley of the Tararua Forest Park in the late 1990s. The only known population of short-tailed bats in the southern North Island, they were once part of a huge population inhabiting the beech forest which extended over much of New Zealand when the North and South Islands were connected. They became isolated during a glacial period in the centre of the North Island, and through volcanic activity – more than 90,000 years ago. It is thought they are related to both the volcanic plateau and the southern short-tailed bats. They’re related to the South American fishing bat and the vampire bat, although our bats don’t eat blood. This unique colony is now under threat from predation.

The lower Waiohine valley in the Tararua Forest Park, where the only population of short-tailed bats has been confirmed in the lower North Island.

In the most ambitious conservation project involving bats attempted in New Zealand, pregnant bats from the Waiohine colony were captured in December 2004 and taken to the Pukaha Mount National Wildlife Centre where they gave birth to 20 pups. The pups are being transferred to Kapiti Island, where it is hoped they will establish a new colony in a predator-free environment, developing a homing instinct to the island. The project is also enabling the development of bat husbandry techniques that will prove valuable in future.

Bats are kept easily in captivity. They were held at Pukaha Mount Bruce in a specially- designed enclosure with a “maternity roost” - a room at the back of the enclosure. It is insulated with thick polystyrene walls and there are grooves on the walls on which the bats can hang.

The bat enclosure is 2.4metres wide x 4.8metres long x 2.1 metres high. Special insect mesh has been tightly fitted onto the inside so the bats can’t escape. The enclosure is nestled among trees for coolness and for high humidity.

Bats like to be kept warm and moist – up to 35 degrees celcius and 90-100 percent humidity. There is also a heat pad inside the maternity roost. Other roosting places have been provided in the form of wooden boxes in the flying part of the aviary, although these have yet to be used.

The bats are fed every evening on a diet comprising mealworms and other insects caught in light traps, which they wash down with loads of honeywater. They are also offered branches of flowering trees, e.g. rata. They feed very well and all the mums reached a good weight, up to 24 grams.

The bats are monitored with infrared video cameras each night. There is a camera inside the maternity roost and two over the feeding platforms. The mums could be seen feeding and grooming their babies, sound asleep with their babies, scuttling around and enjoying social interactions. Three mums were caught on camera arguing over a tasty weta. At night they can be heard chattering away to each other.

Insects are released into leaf litter on the floor of the enclosure and tree ferns and other small trees and bushes have been added to create a “forest-like” environment to make the bats feel at home.

Because the bats are nocturnal they do not react well to be disturbed while they sleep during the day, so their enclosure is off-limits to visitors.

The only other attempt to transfer adult bats (to Ulva Island, off Stewart Island) failed, and the bats are presumed to have flown back to the source colony on Whenua Hou/Codfish Island.

The pregnant females
Two groups of females were caught in the Waiohine Valley, using harp nets placed outside their roosts. When the bats ventured out they hit the harp-like wires and dropped into the trap. One group of nine was caught on the evening of December 15, 2004 and the other 16 on the evening of December 21. All were thought to be pregnant, because of their heavier weight and larger tummies.

They all came from the same area and tree and were brought to Pukaha Mount Bruce National Wildlife Centre in a specially-designed transport box, with calico on the inside. Bats like to snuggle together in a big cluster inside the calico bag.

They settled in captivity very well. They were dosed for mites on arrival and dosed again on January 8. They began giving birth around Christmas Day and some were still pregnant on January 8.

Two of the mums died. One was very small when it first arrived and may have been unwell. It died two weeks after arrival at Pukaha Mount Bruce. The cause of the other death is not yet known but it is likely it died from natural causes.

When the mums have weaned their young, they will be taken back to the tree they were caught at and released.

The juveniles
The bat pups have been thriving. For the first four weeks they were fed milk by their mums and then encouraged to follow mum out and find their own food.

So far there are 20 juveniles. It is likely that some females weren’t pregnant when they came in as it is quite hard to tell. Two pups died. One was stillborn and the other died from a bite to the neck. Such deaths occur in the wild.

By early February the pups were showing signs of flying – stretching wings, flapping and short flights. They began being transferred to Kapiti Island from February 8, once their human carers were confident they could feed themselves.

If the project is successful it will be repeated for the next two years.

The females fly up to eight to 10km to visit groups of calling males in different parts of the forest for about 50m. Their song lasts all night long.

They give birth to only one pup. The juveniles fly at about four to six weeks and reach almost adult size (but not weight) at eight to 12 weeks.

They are vulnerable to such predators as morepork, rats and feral cats. (There is no evidence of stoat predation, but they can climb trees very well !).

Where Short-tailed (Mystacina ) are found in New Zealand.

Short-tailed bat facts

Bats (pekapeka) are the only mammals capable of sustained flight. Of 951 bat species in the world today, just two species survive in NZ – the lesser short-tailed and more common long-tailed bats. They are New Zealand’s only endemic land mammals.

The greater short-tailed bat (Mystacina robusta) was found on two islands off Stewart Island but following an invasion of ship rats, it was last sighted in 1967 and is probably extinct.

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'.

The endangered lesser 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.

The colony of around 200 short-tailed bats found in the Tararua Range in the late 1990s is the only known population of short-tailed bats in the southern North Island. It is thought they are related to both the volcanic plateau and the southern short-tailed bats.

Short-tailed bats are found in indigenous forests where they roost, singly or communally, in hollow trees. The bats go into a 'torpor' in cold weather and stay in their roosts. They wake up as soon as the weather becomes warmer.

The short tailed bat is thought to be a lek breeder, whereby. males compete for traditional ‘singing' posts and `sing' for a female.

Short-tailed bats are small, robust and stocky with prominent pointed ears. They weigh between 11 and 15 grams… although the pregnant females taken to the Pukaha Mount Bruce National Wildlife Centre reached 24 grams in captivity!

Unlike most bats, which catch their prey in the air, the short-tailed bat has also adapted to ground hunting and is one of the few bats in the world which spends large amounts of time on the forest floor, using its folded wings as `front limbs' for scrambling around.

Their 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.

Short-tailed bats roost in trees such as kauri, rimu, totara, southern rata, kamahi and beech. Some roosts have been found in granite sea-caves.

They eat just about anything, apart from blood. Their diet ranges from caught in the air or on the ground – to fruit, nectar and pollen. Few other bat species eat plant matter.

They usually fly quite low, around two to three metres off the ground, but they can fly higher if need be.

They scuttle up tree trunks and along branches with rodent-like agility and they burrow in and under leaf-litter and humus on the forest floor to search for their food.

They also burrow into the rotten wood inside hollow trees and excavate its own tunnels and roost sites inside the trees.

They don’t do a true hibernation and have even been seen flying around in temperatures of minus 20 degrees celcius on Codfish Island.

Find out more about bats here ... (PDF)

Latest progress on the translocation...

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