Short-tailed bat facts
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 also 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. Pups from this unique and isolated colony, born in captivity, have been transferred to Kapiti Island in an attempt to establish an insurance population in a predator-free environment. Find out more about this short-tailed bat translocation.
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.
Fight for survival
Factors thought to have caused the bats decline include habitat loss (clearing of land for farming or the logging of native forest), toxins, introduced predators such as rats, stoats and cats and the disturbance of roosts.
Dactylanthus
Dactylanthus (Dactylanthus taylorii) is a highly unusual plant, and holds a special place in New Zealand's indigenous flora as the only fully parasitic flowering plant.
This fascinating plant grows as a root-like stem attached to the root of a host tree. In response to dactylanthus, the host root moulds into the shape of a fluted wooden rose, which gives the plant its previous common name of wood rose. It is through this placenta-like attachment that dactylanthus draws all its nutrients.
The Maori name for dactylanthus is "pua o te reinga," meaning 'flower of the underworld,' and alludes to the way its flowers emerge from below ground.
Dactylanthus is currently regarded as being in serious decline. A Department of Conservation Recovery Plan is in action.
Interesting ecology
· Dactylanthus has no green leaves or roots of its own.
· Dactylanthus has a strong scent, which is useful for attracting pollinators.
· Dactylanthus is pollinated by the short-tailed bat.
· Dactylanthus has separate male and female plants.
Habitat
Dactylanthus occurs in widely scattered sites. It prefers damp but well drained places, and is often found growing at the head of small streams. It lives where trees form a dense, leafy canopy and the ground is well covered in tall forest, or marginal shrub land. It is normally found on flat sites, but is sometimes found on vertical rock faces where roots are exposed.
Population and range
Since dactylanthus grows underground it is impossible to know the number of plants that exist. However, the distribution and number of plants has declined recently, and there are likely to be only a few thousand remaining.
Dactylanthus has always been a difficult plant to find, and has never been considered common. Dactylanthus is found from Northland to Wairarapa, with the largest populations in East Cape and the central plateau. There is also a small population on Little Barrier Island.
Unfortunately collectors are still digging up the plant, but the practice is discouraged and seems to be declining.
Threats and reasons for decline
· Browsing
o By animals, especially possums, rats and pigs.
· Habitat depletion
o Site destruction and modification
· Collectors
o The digging of the plant for wood rose.
· Decrease in pollination
o There are declining numbers of pollinators and seed dispersing animals, due to the effect of introduced animals.
Potential for recovery
Possum browsing on flowers and preventing seed set is the greatest long-term threat to dactylanthus. Attempts to protect dactylanthus flowers by controlling possum numbers have had limited success.
Protecting the plant from possums with simple cages or exclosures has proved effective in allowing the plants to flower and produce seeds. Hand pollination also increases seed set.
On a positive note, dactylanthus plants flower profusely, which means a large supply of seeds for dispersal if flowers are pollinated.
Recent work has shown that dactylanthus can be established at a new site by spreading seed under a suitable host.
Recovery Plan in action
The original Department of Conservation Dactylanthus taylorii Recovery Plan was approved in 1995. This plan set in place a series of steps that promoted the recovery of Dactylanthus. It also outlined different management options, and a work plan.
This plan was reviewed in August 2001. The review provided a direction for future management. A revised plan was published in 2005.