Mammals

4. New Zealand greater short-tailed bat (Mystacina robusta) CR
The greater short-tailed bat is the largest of New Zealand's three remaining extant bat species. Short-tailed bats use echolocation to hunt aerial invertebrates and olfactory senses to locate prey amongst leaf litter. Like its only close relative, the lesser short-tailed bat, it spends an unusually large proportion of its time on the ground, making it vulnerable to introduced predators such as rats. It disappeared from New Zealand’s North and South islands following European arrival some 200 years ago. It was subsequently restricted to small predator-free islands such as Big South Cape and Solomon Islands until rats were accidentally introduced in 1963.  It is believed this had a catastrophic impact on the remaining population of the species with there being no confirmed sightings since 1967.
54.1
EDGE Score:
6.78
Urgent Conservation Actions
Rat eradication should continue on all small islands in this group, and more surveys for the species are needed to confirm its existence.
Distribution
New Zealand
 
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Evolutionary Distinctiveness
Order: Chiroptera
Family: Mystacinidae
Recent molecular analyses place this species in the superfamily Noctilionoidea (formerly Phyllostomoidea). This superfamily is thought to have evolved in Gondwana and exhibits a greater diversity than any other bat superfamily. It is divided into four families: Mystacinidae (2 species), Noctilionidae or fishing bats (2 species), Mormoopidae or moustached bats (8 species), and the Phyllostomidae or New World leaf-nosed bats (147 species).

The Mystacinidae is believed to be the most basal group in the superfamily, and is the only family not restricted to Central or South America. Until recently, the lesser short-tailed bat (M. tuberculata) was believed to be the sole survivor of this ancient family. Its closest relative, the greater short-tailed bat (M. robusta), was last sighted in 1967 and was believed extinct until recent unconfirmed reports of its continued existence on Big South Cape and neighbouring Putauhina Island, New Zealand.

New Zealand has an extremely poor ancient fossil record and the oldest known fossil remains of Mystacina are probably less than 20,000 years old. However, the genus is considered to be an endemic archaic element of New Zealand's fauna, having no close relatives elsewhere in the world. Estimations for the separation of Mystacina’s ancestors from other noctilionoids vary from 68-35 million years ago. The only ancient mystacinid fossils known are from the early-mid Miocene of Australia, and it is believed that the superfamily evolved and became widespread in the ancient southern supercontinent of Gondwana after New Zealand’s separation around 80 million years ago. The family is thought to have dispersed from Australia to New Zealand sometime after the Oligocene (26 million years ago).
Description
Size: 
Head and body length: 90mm
The greater short-tailed bat is New Zealand’s largest bat. It is around a third larger than its relative, the lesser short-tailed bat, with larger and wider nostrils. Its fur is brownish-grey, short and velvety. Uniquely among bats, the thumb and toe have extra talons.
Ecology
Short-tailed bats not only fly, but are also very agile on the ground. They use echolocation to hunt aerial invertebrates and olfactory senses to locate prey amongst leaf litter. Their diet is also thought to contain pollen, nectar and fruit. They are relatively slow fliers, and seldom get higher than three metres above the ground due to the presence of bird colonies.  When on the ground the wings are tucked away under a membrane, which allows the use of arms as front legs, to run through burrows and forage on the forest floor.  Evidence suggests they are monoestrous breeders, with females having one offspring per year.
Habitat
Very little is known about the habitat preferences of this species. Its relative, the lesser short-tailed bat, is largely restricted to undisturbed old-growth forest and it is likely that this species has similar requirements. Remains of the greater short-tailed bat have been found in limestone caves, suggesting that it roosted in caves. It may also have roosted in tree cavities, although there is no direct evidence for this.
Distribution
This species is endemic to New Zealand. Sub-fossil remains show that the greater short-tailed bat was once found throughout the North and South Islands. However, the species disappeared from these regions following European colonisation around 200 years ago. Populations of greater short-tailed bats were present on Big South Cape and Solomon Islands, off Stewart Island until the mid 1960s. In 1962 or 1963 ship rats were accidentally introduced onto both islands. No confirmed sightings of greater short-tailed bats have been made since 1967, when it was found on Big South Cape Island. However, recent unconfirmed reports provide hope that the species may still survive on this or other small islands near Stewart Island.
Population Estimate
Fewer than 50 mature individuals (possibly extinct).
Population Trend
Unknown.
Status
Classified as Critically Endangered (CR D) on the 2010 IUCN Red List of Threatened Species.
Threats
Evidence from owl middens suggests the species declined rapidly following the introduction of the Kiore or Pacific Rat (Rattus exulans) to New Zealand. The largely terrestrial behaviour of this bat probably made it particularly vulnerable to predation by rats and it seems probable that this introduction was the primary cause of the species’ disappearance.
Conservation Underway
Rats have been eradicated from both Big South Cape and neighbouring Putauhina Island. Following these eradications, there have been several reports of bat sightings from Putauhina, and in 1999 Mystacina-like echolocation calls were recorded from the island. These calls do not belong to the lesser short-tailed bat (M. tuberculata). There have also been two unconfirmed reports of bats being seen on Big South Cape.

M. tuberculata is thought to have once inhabited these islands. However, the nearest populations of this or the only other New Zealand bat species, the long-tailed bat (Chalinolobus tuberculatus) are more than 50 km away. It is therefore possible that M. robusta still survives in low numbers.
Conservation Proposed
Further surveys to confirm the identify and status of the bats on Big South Cape and Putauhina islands are urgently required so that appropriate conservation measures can be implemented should the species be found to survive. Rat eradication should also continue on small all islands in this group.
Links
References
http://www.terranature.org/batGreaterShort-tailed.htm

Hand, S. J. et al. 2009. Bats that walk: a new evolutionary hypothesis for the terrestrial behaviour of New Zealand's endemic mystacinids. BMC Evolutionary Biology 9:169.

King, C. M. 1990. The Handbook of New Zealand Mammals. Oxford University Press.

Lloyd, B. D. 2001. Advances in New Zealand Mammalogy 1990-2000: Short-tailed Bats. Journal of the Royal Society of New Zealand 31(1): 59-81.

Macdonald, D. W. 2009. The Encyclopedia of Mammals. Oxford University Press, Oxford.

Molloy, J. 1995. Threatened Species recovery Plan: Bat (Peka Peka) Recovery Plan (Mystacina, Chalinolobus).Threatened Species Unit Department of Conservation.

O'Donnell, C. 2008. Mystacina robusta. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. <www.iucnredlist.org>. Downloaded on 15 November 2010.

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