Frogs
Archey's frog
New Zealand's native frogs (pepeketua) belong to the genus Leiopelma, an ancient and primitive group of frogs. The frogs have changed very little in 70 million years. They are small, nocturnal, and are hard to see as they camouflage themselves well. Three of our remaining species live on land in shady, moist forested areas, and one is semi-aquatic, living on stream edges.
Facts about frogs
Maud Island frog on lichen, Maud Island
New Zealand's native frogs have several distinctive features, which make them very different from frogs elsewhere in the world:
- They have no external eardrum.
- They have round (not slit) eyes.
- They don't croak regularly like most frogs.
- They don't have a tadpole stage. The embryo develops inside an egg, and then hatches as an almost fully-formed frog. The young of most species are cared for by their parents - for example, the male Archey's frog may carry his young offspring around on his back.
Different species
New Zealand originally had seven species of native frog. Three species have become extinct since the arrival of humans and animal pests, like rats, in New Zealand. The four remaining species are:
Hochstetter's frog - the most widespread, it has been sighted around the upper half of the North Island, including at Waipu, Great Barrier Island, the Coromandel, central North Island, and the Raukumara Ranges. It grows up to 48mm long. It has partially webbed feet, more warts than the other frogs, and is generally dark brown.
Archey's frog - is found only in the Coromandel and in one site west of Te Kuiti. It is the smallest native frog, growing up to 37mm long. It lives in misty, moist areas around 400m in altitude.
Hamilton's frog - one of the world's most endangered frogs, it is found only on Stephens Island in the Cook Strait.
Pepeke
Frog Recovery
New Zealand’s native frogs are in danger, and at the Auckland Zoo’s native frog research centre, a team of experts are trying to solve the mystery of our disappearing ancient frogs.
Bats
Bats are New Zealand's only native land mammals.
There are three species: the long-tailed bat, the lesser short-tailed bat, and greater short-tailed bat.
Greater short-tailed bats are thought to be extinct, while long-tailed bats and short-tailed bats are classed as threatened. They are in danger of extinction in the medium term if nothing is done to reverse their population declines. Therefore, these species are a high priority for conservation.
In proverb, the Maori refer to bats as pekapeka and associate them with the mythical, night-flying bird, hokioi, which foretells death or disaster.
Long-tailed bat
Long-tailed bats were common throughout New Zealand in the 1800s and were recorded in colonies of “scores”, “hundreds”, and “thousands”. By 1900-1930 they were becoming scarce in many districts. Recent surveys indicate that South Island long-tailed bats are rarer than previously thought. They were once common in Dunedin, Invercargill and Christchurch, where they roosted under the wooden bridges across the Avon River until 1885.
Short-tailed bat
The endangered lesser short-tailed bat is an ancient species unique to New Zealand and is found only in a few locations.
Facts about the short-tailed bat
Short-tailed bat taking flax flower
nectar
There are two species of short-tailed bat. 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 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.
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, it is
thought they are related to both the volcanic plateau and the southern
short-tailed bats. 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'.
- Short-tailed bats weigh 12-15 grams, have large pointed ears, a free tail and are a mousy-grey colour.
- Unlike most bats, which catch their prey in the air, the short-tailed bat has 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.
- 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.
- Thought to be a lek breeder, i.e. males compete for traditional `singing' posts and `sing' for a female.
- 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.
Threats to the short-tailed bat
Short-tailed bat and kakabeakFactors thought to have caused the bats decline include habitat loss (clearing of land for farming or the logging of native forest), introduced predators such as rats, stoats and cats and the disturbance of roosts.
Old trees for bats
Bats are New Zealand’s only terrestrial native mammals. There are three species. Greater short-tailed bats are thought to be extinct, while long-tailed bats and the lesser short-tailed bats are classed as threatened. They are in danger of extinction in the medium term if nothing is done to reverse their population declines. Therefore, these species are a high priority for conservation.
Bats were common throughout New Zealand in the 1800s when they were recorded in colonies of “scores”, “hundreds”, and “thousands”, but by 1900-1930 they were becoming scarce in many districts. Bats still occur widely, from Northland south to Stewart Island, but their distribution is patchy, and their numbers very low in many areas.
Multiple threats
New Zealand bats roost in tree hollows and their decline has been attributed to clearance and logging of lowland forests, and cutting of old-age trees for firewood. Bats are also vulnerable to human interference and to predation by introduced animals such as cats, possums, rats, and stoats, and exclusion from roosts by introduced mammals, birds and wasps.
Importance of old-aged forest trees for bats
The majority of New Zealand bats live within areas of native forest. Recent research by the Department of Conservation has revealed that bats actively select the largest and oldest trees in the forest for roosting and breeding. In Fiordland, long-tailed bats shelter and breed in cavities in old-aged trees. 95% of roosts are in mature lowland forest on the valley floor. Individual bats range over 50 square kilometres when feeding at night, but always return to traditional areas within the forest during the day. Within the roosting areas they use clumps of 3-6 trees over a few days, then move to a new clump of trees close by.
Short-tailed bats have similar requirements but usually live deeper within the forest.Implications of logging
Studies indicate that logging would be detrimental to bats if roosting trees are felled. Large diameter trees, such as those preferred by bats, have been a target for logging in the past. The Resource Management Act (1991), Forests Amendment Act (1993) and Rules of some District Plans require that wildlife populations, particularly populations of threatened species, be sustained at their current levels through logging operations. Any sustainable management systems proposed for use in the future need to leave sufficient trees to ensure bat populations survive. Sustainable Management Plans need to demonstrate that safeguards are in place so that bat populations are not threatened.
Roost trees for short-tailed bats
Short-tailed bats living in mixed beech forest roost in large splits and hollows mainly in large diameter red beech trees 40-160 cm in diameter. Bats in podocarp-hardwood forest show a similar dependence on large diameter trees, including Hall’s totara, rimu, southern rata and miro. Most roosts are in trees greater than 80 cm in diameter, but some are also in smaller trees. These are most often used by solitary bats and groups that require smaller cavities for hibernation. Short-tailed bats may use a particular roost for just a day, or continuously up to 6 weeks, before moving to another tree roost.
Roost trees for long-tailed bats
Long-tailed bats roost in smaller cavities than short-tailed bats, high up trees (usually 15-20 metres high). Roost trees also have large trunk diameters. 80% of roosts are in trees greater than 80 cm, and up to 250 cm, in diameter. Such trees are usually 200-650 years old. In Fiordland, roosts were in red beech (74%), standing dead trees (21%), silver beech (4%) and mountain beech (1%). Long-tailed bats move to a new roost tree virtually every day and one group can use over 100 different roosting trees. In Northland, long-tailed bats roost in the large kauri trees. In podocarp-hardwood forests roosts have been found in rimu, miro, kahikatea, matai, and totara, from 50-180 cm in diameter.
How to protect roosting trees for bats
- Identify and protect bat roosting trees. Logging generally targets
a significant proportion of trees preferred by bats. Unless roosting
patches are identified and protected, there is a high risk of localised
tree selection wiping out a population. Bat detectors can be used to
determine the presence of bats. The Department of Conservation can help
by letting you know if there are bat records in your region.
- Where bats are found, do not disturb them It is safe to watch bats
as they emerge from roosts or feed, but sit quietly so they will not be
frightened away.
- Protect standing dead trees and old-age trees with cavities Dead
trees and old trees with hollows and cavities are still valuable for
wildlife. Bats rest by day and breed in cavities in old-aged trees.
Bats move to a new roost tree regularly so are not always present at a
site.
- Demonstrate in Sustainable Management Plans that sufficient roosting, breeding and feeding habitat remains to sustain bat populations following timber extraction. In addition to protecting existing roosts, remember to provide for the next generations of roost trees to grow old enough to replace existing ones.
