Little New Zealand bat
| Little New Zealand bat | ||||||||||||
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Drawing of a small New Zealand bat |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Mystacina tuberculata | ||||||||||||
| ( Gray , 1843) |
The New Zealand lesser bat ( Mystacina tuberculata ) is a species of bat that is native to New Zealand. Along with the great New Zealand bat ( Mystacina robusta ), it is the only species within the genus and family of New Zealand bats and possibly the only species still alive, as the great New Zealand bat has been missing since 1967.
The generic name Mystacina is derived from the Greek "mustax" (= mustache) and refers to the striking whiskers around the muzzle of New Zealand bats. The species name tuberculata refers to the small knots on the lower lip of another bat species, Chalinolobus tuberculatus , with which the New Zealand lesser bat was originally confused. In fact, the discoverer of the species, John Edward Gray, was not aware that the bats he described in New Zealand are two species from different genera.
description
The Little New Zealand bat has a thick brown coat. The ears, flight skin , nose and feet are gray-brown and bare. The length of the body is 60–70 mm, the wingspan 280–300 mm and the weight 10–22 g. The nostrils are noticeably large and elongated like a tube, the snout is relatively long and provided with a series of whiskers.
The small New Zealand bat is, as the name suggests, with a shorter forearm (40–45 mm) smaller than the large New Zealand bat (45.3–47.5 mm). It differs from Chalinolobus tuberculatus , the only other bat species in New Zealand, by its pointed ears, which protrude beyond the snout, and the tail, which protrudes 6–8 mm from the tail membrane. The ears of Chalinolobus tuberculatus are round and shorter, and the tail of this species is completely embedded in the tail membrane.
Way of life
The New Zealand lesser bat , like most bats, is nocturnal. It feeds opportunistically and depending on the availability of insects, nectar and fruits. During a single night the animals can consume up to 50% of their body weight. Basically half of the diet consists of insects such as beetles , flies , moths and wetas , but other arthropods such as spiders , harvestmen and millipedes are also eaten. Among the plants that are on the dining list of small New Zealand bat include the bracts of Freycinetia baueriana (also called "Kiekie" a screw tree greenhouse ), berries Collospermum hastatum and C. icrospermum , fruits of the tree Elaeocarpus gyrus , pollen from iron wood ( Metrosideros , also called "Rata" and "Pohutukawa") and the silver tree Knightia excelsa . The little New Zealand bat is therefore an important seed disperser and pollinator of these plants. As an adaptation to the consumption of nectar, the tongue is extended and can be extended up to 12 mm.
The small New Zealand bat prey on insects and arthropods in flight or on the ground. Thanks to the wide wings, it is very maneuverable and can also take off directly from the ground. The species is known to be able to climb and walk around. She uses her feet and wrists to walk on all fours. The little New Zealand bat can fold its wings so that the fingers are protected in a sheath-like, thickened part of the flight membrane . The calcar lifts the tail skin when the bat moves on the ground. The prey is located in the air by echolocation . If the bat is sitting on a tree or another elevated place, it also passively uses the noises emitted by the prey to track down the prey. When the Little New Zealand bat searches for arthropods on the ground, it relies on a combination of acoustic signals and smells.
The small New Zealand bat spends the day in tree hollows, where it can be found in groups of up to 6,000 animals as well as alone. When the animals are alone, they occasionally go to torpor during the day . Large trees such as the Kauri tree ( Agathis australis ), Metrosideros excelsa (also called "Pohutukawa") and their sister species, the South Island ironwood ( Metrosideros umbellata ), Austrotaxus spicata ("Matai") from the family are particularly suitable as sleeping places the yew family , the silver beech ( Nothofagus menziesii ) and the beech species Nothofagus fusca , the stone beech species Podocarpus hallii and Prumnopitys ferruginea , the New Zealand warts ( Dacrycarpus dacrydioides ) and the riminumu resinress ( Dacrydium ). The New Zealand lesser bat can sometimes be found in crevices that it has gnawed into the tree with its teeth, which is unusual behavior for tree-dwelling bats. In a dead, fallen kauri tree, a veritable system of corridors was discovered that was inhabited by around 500 animals. The temperature within a sleeping area can fluctuate between 15 and 39 ° C and the humidity is usually 100%. The little New Zealand bat changes its sleeping places on average every 4 days. A tree hollow with thousands of individuals can therefore be deserted the next day. The species does not actually hibernate , but can go to torpor for up to 10 days during cold periods in winter to save energy.
Reproduction
During the mating season males occupy individual hanging places in trees, where they for the females courtship . The males rub the entrance of the tree cavity with an oily secretion from their throat gland, which gives off a musky odor and is intended to attract the females. At night the males sing from their courtship area. A single chant consists of repetitive stanzas, each lasting 10–40 minutes, and is even audible to the human ear. The males use it to attract females from a distance of up to 10 km and even sing in strong wind and rain. The tree hollows are actively defended against intruders by the males and reused for several consecutive years.
The reproductive cycle is highly dependent on the region. The New Zealand lesser bat is monoestrous and usually mates in late summer or fall. During the winter, the fertilization of the egg or the development of the fetus is suspended and the gestation period does not begin until spring. In summer, the females give birth to a single young each. An exception is the region around 35 ° S, where birth takes place in December and January. Before or shortly after birth, the females gather in nurseries. Newborns weigh about 5 g and have a forearm length of about 19 mm. Shortly after birth, the young are hairless and wrinkled, with dark skin pigmentation . The eyes are still closed for the first two weeks after the birth. During this time, the females return to the nursery again and again at night while searching for food to suckle the young. After 3 weeks, the milk teeth are replaced by the permanent teeth and the young begin to move their wings. After 4 weeks the young are completely hairy and able to fly and after 6 weeks they leave their nursery.
Threat and protection
The IUCN classifies the population of the New Zealand bat as endangered ("vulnerable"). The reason for this is their small distribution area, the scattered occurrence of small populations with little genetic exchange among each other and the steady decline in the number of individuals. The species is protected by the New Zealand's Wildlife Act of 1953.
Until the introduction of other mammals, the New Zealand lesser bat had few predators. With the arrival of humans, however, the black rat ( Rattus rattus ) and the much smaller Pacific rat ( Rattus exulans ) as well as ermines came to the islands. With their emergence, both New Zealand bat species disappeared from Big South Cape Island and the Solomon Islands . In addition, New Zealand bats are often preyed on by domestic cats . Naturally occurring hunters of small New Zealand bat are the New Zealand morepork ( Ninox novaeseelandiae ), the Maori falcon ( Falco novaeseelandiae ) and until its extinction around 1960 the Weißwangenkauz ( Sceloglaux albifacies ).
On Codfish Iceland , the stocks have recovered after all Pacific rats were removed from the island. There are also initial successes in the Eglinton Valley , where there is a program to control the rat and ermine population.
distribution and habitat
The New Zealand lesser bat is endemic to New Zealand , but only occurs in 30% (2,000 km²) of the country. On the main island, the well-known areas in which the bat occurs include the Omahuta Forest and Puketi Forest near Kaikohe , the Waipoua Forest and Warawara Forests , as well as the primeval forests from the volcanic mountain Mount Taranaki to the eastern point of the main island of New Zealand, the East Cape , and south to the Tararua District . On the South Island there are colonies in the Oparara Basin and the Eglinton Valley , with individual reports from Punakaiki in Paparoa National Park and from the Dart Valley . Larger colonies exist on Little Barrier Island and Codfish Island .
literature
- GG Carter & DK Riskin: Mystacina tuberculata . In: Mammalian Species , No. 790, pp. 1-8
