Conservation of our native bats – pekapeka

New Zealand bats are fully protected by the Wildlife Act 1953, and their habitats are also protected by the Resource Management Act 1991. There are a variety of conservation efforts being undertaken to protect bats/pekapeka – New Zealand’s only native land mammal.

Bat species

There are currently two species of bats in New Zealand: the long-tailed bat (Chalinolobus tuberculatus) and the short-tailed bat (Mystacina tuberculata). The greater short-tailed bat (Mystacina robusta) is believed to be extinct as it has not been spotted since 1967.

Both our native bat species reproduce once a year, giving birth to only one pup (baby), so their population size increases slowly. This makes the species vulnerable to extreme population changes. If a population suffers a large loss of individuals from disease or environmental events, it takes a long time to recover. Often this results in a bottleneck effect, which reduces the genetic pool of a population.

Cause for species decline

It is thought that the decline in bat numbers in New Zealand is due to:

• habitat loss – land clearance, particularly of large trees and forests, reducing food sources
• introduced predators – primarily rats, stoats and feral cats
• disturbance of their roosts – removal of dead trees and old trees, which are often favourite roosts for bats with their hollows and cavities that are perfect for breeding
• competition – in beech forests, wasps compete for food, consuming both honeydew and insects.

Moreporks are natural predators of bats, but they will only kill one bat at a time. Other predators, such as cats, can kill a whole colony. For example, in just 1 week, one cat killed 100 bats in a roosting tree in Rangataua, Tongariro National Park.

There are also concerns that recent plant diseases, such as kauri dieback and myrtle rust, that are within the area of a bats range could threaten their roost trees.

Conservation efforts

Both the long-tailed and short-tailed bats need protection for their continued survival, and the Department of Conservation (DOC) runs various programmes to gather more information about them. The long-term goal for the DOC recovery programme for our New Zealand bat species is: “To ensure the perpetuation of all extant bat species and subspecies throughout their present ranges and where feasible establish new populations within their historical ranges.”

DOC is surveying bats in many areas to determine the present distribution of the two species.

Bats can be very difficult to find and hard to monitor. In this video DOC Senior Biodiversity Ranger Ali describes finding them as being a bit like a treasure hunt. They are very small, well camouflaged, and as they are nocturnal animals, they can be difficult to see in the dark.

[Native bats are] absolute characters. They’re like little pit bulls with wings – they’ve got attitude!

Ali, Senior Biodiversity Ranger, Department of Conservation

Bat-surveying tools

DOC staff and trained volunteers use electronic bat boxes that can pick up high-frequency echolocation calls made by bats. Once an area has been identified as having bat activity, nets can be set up.

There are two types of nets commonly used – mist nets and harp traps – both with the aim of capturing bats when they fly into the net and then catching them in the bags that are part of the net. Mist nets are made of fine nylon or terylene netting with bags or pockets attached to it. These nets are very effective at catching the lesser short-tailed bats, but long-tailed bats can easily detect them. Harp traps comprise of a frame with two rows of very fine thread net and a catching bag at the base.

Capturing bats allows researchers to identify the bat species, check its health and gather other information, including genetic samples. Tiny radio transmitters specially designed for bats are sometimes attached so the bats can be tracked back to their current roost trees. The transmitters are attached to the bat with a special glue so they fall off after 2–3 weeks, but the transmitter’s battery lasts a bit longer so they can be found and used again.

Research is revealing the complex social systems of short-tailed and long-tailed bats, and this knowledge will help to ensure their ongoing survival. Creating a database of long-term data will also ensure we have information on population and habitat changes over time and conservation efforts can be measured.

Create a bat-friendly garden

If you are in an area with bats, why not make your garden a bat-friendly one? To encourage bats, try to:

• eradicate pests, particularly rats
• keep cats indoors at night
• remove invasive weeds, such as the moth plant (Araujia sericifera) and climbing asparagus (Asparagus scandens), which can suffocate the larger trees where bats may roost
• plant trees with a gnarly bark such as pūriri (Vitex lucens), tōtara (Podocarpus totara) and pukatea (Laurelia novae-zelandiae) – bats like to roost under the bark and also in the hollows in cabbage trees (Cordyline australis).
• install bat-roosting boxes – care must be taken with installation as bats prefer to be high in trees.

It might take a while for bats to move in, but in the meantime, other native species such as wētā will appreciate your efforts. Bats often change their roosting areas and will also return to older roosts.

If you find bats, it is very important to not disturb them. Just sit quietly and observe them in the early evening as they emerge from roosts or to feed. Many councils have bat reporting forms – check your local regional, district or city council websites. Providing information about where bats are located will help councils and DOC make decisions on how to best protect these special taonga.