New Zealand short-tailed bats

(Mystacinidae)

Class Mammalia

Order Chiroptera

Suborder Microchiroptera

Family Mystacinidae

Thumbnail description
New Zealand short-tailed bats are medium-sized, robust bats; they have evolved a suite of unusual characteristics, including a unique wing-folding mechanism, additional spurs below each claw, and robust legs that permit efficient movement along the ground and tree trunks; only bats demonstrated to be omnivorous

Size
Forearm length 1.5–1.8 in (40–48 mm); total length 2.3–3.5 in (60–90 mm); wingspan 11–12.2 in (280–310 mm); ear lengths 0.6–0.7 in (17.5–18.6 mm); weight 0.4–1.2 oz (11–35 g)

Number of genera, species
1 genus; 2 species

Habitat
Native forests and scrub habitats of New Zealand

Conservation status
Extinct: 1 species; Vulnerable: 1 species

Distribution
New Zealand

Evolution and systematics

Mystacinidae has been aligned with several other bat superfamilies, including Vespertilionoidea, Emballonuroidea, and Noctilionoidea. Traditional classifications have primarily aligned Mystacinidae with the vespertilionid family Molossidae. Assessing relationships between Mystacinidae and other bat families with morphology has proven difficult since so many mystacinid morphological features are unique. Recent analyses of molecular evidence, including DNA hybridization, immunology, and mitochondrial DNA sequences, along with systematic analyses of morphological traits, have provided strong evidence that Mystacinidae is a member of the Noctilionoidea, including the bat families Noctilionidae, Mormoopidae, and Phyllostomidae. This finding lends support to the hypothesis that the ancestral lineage leading to Mystacinidae originated in the New World tropics.

Physical characteristics

New Zealand short-tailed bats are robustly built, with stocky bodies and short, stout legs. The feet are broad, short, and are positioned under the body during movement on the ground and in trees, unlike other bats. The feet have grooved soles and needle-sharp claws, which are further modified with denticles, or talons, at the base of each claw and the thumb. These modifications of the legs, feet, and claws make New Zealand short-tailed bats capable of running on the ground, climbing, and burrowing.

The dark brown fur is short, thick, and velvety, with white-tipped hairs that give it a frosted appearance. The head tapers to a slender, truncated muzzle with prominent, oblong nostrils and a set of stiff whiskers. The ears and tragi are long, slender, and pointed. The wing membranes are unique among bats, being thickened and leathery along the body, forearm, and lower leg. The remainder of the wing membrane can be folded under this thickened portion, protecting it during climbing and running. The tail emerges from the dorsal surface of the tail membrane.

The teeth are cuspidate, with chisel-like incisors. The number of teeth is reduced through loss of incisors and premolars to a total of 28 (I1/1 C1/1 P2/2 M3/3). The tongue is extensible and covered with small projections (papillae), and there is a gap between the front incisors.

Distribution

New Zealand short-tailed bats are found only in New Zealand. Both species are thought to have once occurred throughout the islands of New Zealand. Mystacina tuberculata is now restricted to a portion of its former range. Mystacina robusta was restricted to a single locality in recent history and is now presumed extinct, having not been observed since 1965.

Habitat

Both species of Mystacina occupy the moist forests of New Zealand and muttonbird scrub (Olearia sp.) habitats found on certain islands. Roosts are found solely within native, broadleaf forests, although foraging may occur in scrub habitats and along coastlines. Roosts are typically in trees but may also occur in caves, burrows, and houses.

Behavior

Mystacinid bats are unusual for their ability to run, climb, and burrow. They have been described as having rodent-like agility and are frequently seen scurrying along tree branches and the ground. Their robust and modified limbs and feet are clearly adaptations for a more terrestrial lifestyle than is found in most bats, except perhaps vampire bats. They burrow under leaf litter in search of food and excavate their own tunnels and roosts in rotten logs.

They are active primarily at night, emerging from roosts several hours after dusk. Flight is typically slow and low, with bats flying 6.5–9.8 ft (2–3 m) off the ground. Echolocation calls are frequency modulated sweeps with maximum energy between 60 and 65 kHz. They become inactive during cold weather but do not hibernate, as they emerge to forage in winter when the weather is warm.

Feeding ecology and diet

New Zealand short-tailed bats have an unusually broad diet: they are essentially omnivorous, which is unusual among bats. Foods eaten include arthropods taken in flight and from surfaces, nectar, pollen, and fruit. They have also been observed eating nestling and adult birds and chewing meat and fat from muttonbirds killed by humans.

Reproductive biology

These bats reproduce once yearly, giving birth to one young. Births may be synchronized. The season of mating and births seems to vary with latitude. The mating system of these bats is not known.

Conservation status

New Zealand short-tailed bat populations have been negatively affected by introduced species such as rats, stoats, and cats, which prey on them in roosts and while foraging. They are particularly vulnerable because they forage on the ground and may occupy roosts accessible to predators. The introduction of rats to islands occupied by greater New Zealand short-tailed bats is likely to have resulted in their extinction. Destruction of native forests also threatens these bats, as they rely on native trees for roost sites and food.

Significance to humans

If Mystacina robusta is, indeed, extinct, then Mystacina tuberculata is the only surviving member of a unique bat family endemic to New Zealand. These bats represent a unique evolutionary history and are part of the rich cultural and natural heritage of New Zealand. Their nectar-feeding and insecteating habits also make them valuable pollinators of native trees and predators of insect pests.

Species accounts

List of Species

Lesser New Zealand short-tailed bat

Mystacina tuberculata

taxonomy

Mystacina tuberculata Gray, 1843, New Zealand. Three subspecies are recognized.

other common names

English: Lesser short-tailed bat, northern short-tailed bat, New Zealand long-eared bat.

physical characteristics

The smallest of the New Zealand short-tailed bats. Total length is 2.3–2.6 in (60–68 mm); forearm length 1.5–1.7 in (40–45 mm); wingspan 11–11.4 in (280–290 mm); weight 0.38–0.52 oz (11–15 g) (up to 0.65 oz [18.5 g] in pregnant females). There is considerable variation in size among the three subspecies, with body size increasing toward the south. Fur is dark brown, short, thick, and velvety with white-tipped hairs.

distribution

Based on current distribution and the locations of subfossils, the former distribution of M. tuberculata included all of the New Zealand islands. Populations of the three subspecies are now found only in portions of their former range. Kauri forest short-tailed bats (M. t. aupourica) are found in Omahuta kauri forest, Northland, and Little Barrier Island. Volcanic plateau short-tailed bats (M. t. rhyacobia) are found in the podocarp-hardwood and Nothofagus forests of the volcanic plateau. Southern short-tailed bats (M. t. tuberculata) are currently found only in Tararua Forest Park on North Island, in Northwest Nelson Forest Park on South Island, and on Codfish Island. (Specific distribution map not available.)

habitat

Found primarily in the native forests of New Zealand. They are sometimes observed flying along coastlines and foraging in the scrub habitats (Olearia sp.) in which petrel and mutton-bird breeding colonies occur. Roosts have been found in kauri (Agathis australis), rimu (Dacrydium cupressinum), totara (Podocarpus totara and P. hallii), southern rata (Metrosideros umbellata), kamahi (Weinmannia racemosa), and beech (Nothofagus sp.) trees and in granitic and pumice caves, as well as houses.

behavior

Roost in small groups, emerging one to two hours after dark to forage in forested and scrub habitats.

During the breeding season, males and females establish separate colonies. Individual males travel, after dark, to small, hollow trees where they utter a repetitive, high-intensity call, which has been likened to a song. Radio-tagged females were recorded visiting calling males each evening before beginning their foraging flights. This provocative observation suggests a lek-mating system in Mystacina, but requires further investigation.

feeding ecology and diet

Eat both flying and non-flying arthropods, nectar, pollen, fruit, and other plant material. They have also been observed eating nestling and adult birds and chewing meat and fat from harvested seabirds.

reproductive biology

One young is born each year. Mating has been observed in autumn, but may occur throughout winter and spring. Births occur in the austral summer (December and January) in northern populations and later (April–May) in southern populations. Young develop quickly, being able to fly at 4–6 weeks and reaching adult size at 8–12 weeks. Mating system not known, but thought to be a lek-mating system.

conservation status

Restricted to a portion of their former range, leaving them in isolated populations. They are vulnerable to predation by introduced species such as stoats, cats, and rats, and to the destruction of their forest habitat. They are currently listed as Vulnerable by the IUCN and in the New Zealand Red Data Book, but may be moved into the Endangered category.

significance to humans

Likely pollinators of native trees and may control arthropod pest populations.

Greater New Zealand short-tailed bat

Mystacina robusta

taxonomy

Mystacina robusta Dwyer, 1962, New Zealand.

other common names

English: Greater short-tailed bat, southern short-tailed bat, Stewart Island short-tailed bat.

physical characteristics

The larger of the two mystacinid species. Total length 3.5 in (90 mm); forearm length 1.7–1.8 in (45–48 mm); wingspan 11.4–12.2 in (290–310 mm). Size may have decreased from north to south. Appearance is similar to M. tuberculata.

distribution

Subfossil finds indicate these bats once occurred throughout the New Zealand islands. However, they have not been collected from the three main islands since the beginning of European colonization in 1840. Until 1965, living greater short-tailed bats were known only from two, rat-free islands off Stewart Island. (Specific distribution map not available.)

habitat

The islands on which these bats were found in recent times are primarily composed of a scrub habitat, with a central area of broadleaf forest. Known roost sites were in granitic caves along the coastline.

behavior

May have been even more terrestrial than their smaller congener. They were known to occupy seabird burrows, dig in the soil, and were remarkably agile on the ground. They emerged from roosts one to two hours after dark and tended to fly low to the ground. They did not appear to hibernate, being observed flying throughout the austral winter.

feeding ecology and diet

Probably shared the broad diet of their living relative. Stomach analysis of two specimens yielded pollen and fern spores and they were observed eating the meat and fat of harvested seabirds.

reproductive biology

The few existing observations suggest these bats had one young yearly, but the timing of mating and births is unknown.

conservation status

Have not been observed since 1965 and are presumed Extinct.

significance to humans.

Were likely pollinators of native trees and predators of insect pests.

Resources

Books

Daniels, M. J. "Greater Short-tailed Bat." In The Handbook of New Zealand Mammals, edited by Carolyn M. King. Auckland: Oxford University Press, 1995.

Daniels, M. J. "Lesser Short-tailed Bat." In The Handbook of New Zealand Mammals, edited by Carolyn M. King. Auckland: Oxford University Press, 1995.

Hill, John E., and James D. Smith. Bats, A Natural History. London: British Museum of Natural History, 1984.

Koopman, Karl F. "Chiroptera: Systematics." In Handbook of Zoology, Volume VIII, Mammalia, edited by J. Niethammer, H. Schliemann, and D. Starck. Berlin: Walter de Gruyter, 1994.

McKenna, Malcolm C., and Susan K. Bell, eds. Classification of Mammals Above the Species Level. New York: Columbia University Press, 1997.

Nowak, Ronald M. Walker's Bats of the World. Baltimore: Johns Hopkins University Press, 1994.

Simmons, Nancy B., and Jonathan H. Geisler. "Phylogenetic Relationships of Icaronycteris, Archaeonycteris, Hassianycteris, and Palaeochiropteryx to Extant Bat Lineages, with Comments on the Evolution of Echolocation and Foraging Strategies in Microchiroptera." Bulletin of the American Museum of Natural History, Number 235. New York: American Museum of Natural History, 1998.

Periodicals

Arkins, A. M., A. P. Winnington, S. Anderson, and M. N. Clout. "Diet and Nectarivorous Foraging Behaviour of the Short-tailed Bat (Mystacina tuberculata)." Journal of Zoology 247 (1999): 183–187.

Hill, J. C., and M. J. Daniel. "Systematics of the New Zealand Short-tailed Bat Mystacina Gray, 1843 (Chiroptera: Mystacinidae)." Bulletin of the British Museum of Natural History, Zoology 48 (1985): 279–300.

Mayer, G. C., J. A. W. Kirsch, J. M. Hutcheon, F. J. Lapointe, and J. Gingras. "On the Valid Name of the Lesser New Zealand Short-tailed Bat (Mammalia: Chiroptera)." Proceedings of the Biological Society of Washington 112 (1999): 470–490.

Parson, Stuart. "Search-phase Echolocation Calls of the New Zealand Lesser Short-tailed Bat (Mystacina tuberculata) and Long-tailed Bat (Chalinolobus tuberculatus)." Canadian Journal of Zoology 75 (1997): 1487–1494.

Van Den Bussche, Ronald A., and Steven R. Hoofer. "Further Evidence for Inclusion of the New Zealand Short-tailed Bat (Mystacina tuberculata) within Noctilionoidea." Journal of Mammalogy 81 (2000): 865–874.

Van Den Bussche, Ronald A., Steven R. Hoofer, and Nancy B. Simmons. "Phylogenetic Relationships of Mormoopid Bats Using Mitochondrial Gene Sequences and Morphology." Journal of Mammalogy 83 (2002): 40–48.

Webb, P. I., J. A. Sedgeley, and C. F. J. O'Donnell. "Wing Shape in New Zealand Lesser Short-tailed Bats (Mystacina tuberculata)." Journal of Zoology 246 (1998): 462–465.

Worthy, T. H., M. J. Daniel, and J. E. Hill. "An Analysis of Skeletal Size Variation in Mystacina robusta Dwyer, 1962 (Chiroptera: Mystacinidae)." The Royal Society of New Zealand 23 (1996).

Tanya Dewey