Small short-nosed bag
| Small short-nosed bag | ||||||||||||
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Small short-nosed pouch, in the Cranbourne Botanical Gardens, Victoria |
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| Isoodon obesulus | ||||||||||||
| ( Shaw , 1797) |
The small short-nosed pouch ( Isoodon obesulus ) is an Australian marsupial belonging to the genus of the short-nosed pouch . It is mainly found in the south of Australia. Although it is not listed as endangered, its population numbers have been decimated , especially due to the introduction of the red fox in recent decades.
features
The German-language name (Kleiner Kurznasenbeutler) obviously refers to the supposedly smaller body size in contrast to the Großer Kurznasenbeutler . In fact, however, the difference is marginal and there is great overlap in the lengths of both species. The total length is 31 to 61 cm for males and 25 to 46 cm for females, about a third of which is the tail. Males are not only larger, but also heavier than females, by 40 to 50%. In addition, animals in Tasmania are on average larger and heavier than on the Australian mainland. Tasmanian males weigh on average 1.2 kg and females 1 kg. On the mainland even the heaviest representatives remain below these average dimensions.
Small short-nosed sacs have a plump shape, a snout that is quite short and conical for a nose- cone and small ears. The hair is short, bristly, shiny and three-colored. Each hair on the top is light at the base, black towards the center, and yellowish at the top. The overall impression is a gray-brown fur with irregular black dashes. The underside is cream colored. The tail is also brown on top and whitish on the underside. The eyes are black and the pouch that opens back contains eight teats. Below the ears there are glands that swell considerably, especially during the mating season, and release large amounts of secretion when excited.
A little short-nosed bagger can continuously reach a maximum speed of 14.3 km / h.
distribution and habitat
Before the colonization of Australia by Europeans, the area of distribution of the small short-nosed pouch looked as follows: Between Sydney and Adelaide the hinterland of the coast was completely populated. There were also isolated occurrences of it in Western Australia , Queensland and Tasmania . Today the range is much more fragmented. The species is extremely rare in New South Wales . In Victoria they can be found in the coastal plains, the Grampians and Dandenongs . In South Australia , where the small short-nosed pouch is generally rare, it is most likely to be found on the Eyre Peninsula , in the Mount Lofty Ranges and on the Fleurieu Peninsula , as well as on some offshore islands; it is even quite common on Kangaroo Island due to the lack of foxes. In Western Australia there is a declining population in the southwest, in Queensland a small distribution area on the Cape York Peninsula . The populations are doing particularly well in Tasmania, where the species is widespread. Subfossil remains can also be found on numerous small islands of the Bass Strait (partly up to the 20th century), but currently small short-nosed pouches only live there on the Inner Sister Island, which belongs to the Furneaux group .
Small short-nosed beetles inhabit a variety of habitats, but there must always be sufficient vegetation. Regular rains are just as important. The habitats include forests as well as heather and scrubland.
Way of life
activity
Observations in Tasmania as well as those in captivity show that the small short-nosed bucket is an exclusively nocturnal animal. It becomes active about an hour after sunset and remains so for six to eight hours. The animal then moves with its nose on the ground in search of food. If something edible is detected with the help of the sense of smell, it is dug up with the front paws.
Small short-nosed pouches are strict loners who - with the exception of the mating season - avoid each other. If two males meet, the result is aggressive behavior in which the opponents attack each other by scratching with their front paws and biting until one of them takes flight. The range of action of an animal is between 1 and 5 hectares , depending on the population density . The animals spend the day sleeping in a small hollow in a place protected by dense vegetation.
food
The small short-nosed bag is omnivorous . Food includes insects and their larvae, arachnids, woodlice and worms, as well as mushrooms, roots, grasses, fruits and ferns. However, invertebrates always make up the majority of the diet.
Reproduction
The gestation period is less than 15 days. The litter includes up to five young animals, but there are usually two or three. The newborns initially weigh 350 mg, but develop quickly in the pouch and can leave it after an average of 53 days. Small short-nosed pouches are sexually mature after just three to four months. It is not uncommon for them to have their first litter in the year of their birth. A female can litter up to four times a year, which means an extraordinarily high rate of reproduction. The service life is a maximum of four years.
Enemies
Snakes, owls and bag martens are among the natural enemies of the small short-nosed pouch . They belong to the main prey of the black-tailed pouch marten in Western Australia. With the colonization of Australia by the Europeans, numerous enemies were added. In addition to dogs and cats, the red fox should be mentioned in the first place , which heavily affects the population.
Systematics and names
The small short-nosed pouch was first described scientifically by George Shaw , who named it Didelphis obesula in 1797 . The binomial Isoodon obesulus , which is valid today , was first used in 1922 by Oldfield Thomas . The specific epithet obesulus is a diminutive of obesus , which means obese.
While in German the body size is used to distinguish it from the related large short-nosed pouch, in English it is common. Here the animal is called the Southern Brown Bandicoot , while the Great Short-nosed Bumblebee is the Northern Brown Bandicoot . The name quenda , which is borrowed from an Aboriginal language , is common locally in Western Australia .
There is no agreement on the number of subspecies. In addition to the nominate form, Driessen & Rose only know one other subspecies, Isoodon obesulus nauticus , whose distribution is limited to the Franklin Islands in the Nuyts Archipelago . Other publications also name the subspecies Isoodon obesulus fusciventer (Western Australia), Isoodon obesulus affinis (Tasmania) and Isoodon obesulus peninsulae (Queensland). In the case of the latter, DNA analyzes give rise to the assumption that it is more closely related to the Golden Short-nosed Bubbler than to other Small Short-nosed Burses, which is why it has been suggested either to add it to this species or to treat it as a separate species. In early 2018, the Western Australian form Isoodon obesulus fusciventer became an independent species.
Threat and protection
The World Conservation Organization IUCN lists the small short-nosed bag as a least concern (not endangered). This is justified with the regional frequency in Western Australia, Tasmania and other islands. However, regionally it sometimes looks different. The states of New South Wales and South Australia see the species as endangered on their territories.
The regional decline is mainly related to two factors: the destruction of natural habitats and the introduction of predators by Europeans. The red fox in particular has a dramatic impact on populations; wherever it is missing, the stocks are still doing comparatively well. It is the same in Tasmania, where the red foxes were completely pushed back in a ten-year eradication program.
Individual evidence
- ↑ a b c d e Driessen & Rose 2015, p. 113
- ↑ a b c Driessen & Rose 2015, p. 114
- ↑ a b c d Driessen & Rose 2015, p. 119
- ↑ a b c Driessen & Rose 2015, p. 115
- ↑ a b c Driessen & Rose 2015, p. 118
- ↑ a b c d Driessen & Rose 2015, p. 117
- ↑ a b Driessen & Rose 2015, p. 116
- ↑ M. Westerman & al .: Phylogenetic relationships of living and recently extinct bandicoots based on nuclear and mitochondrial DNA sequences . In: Molecular Phylogenetics and Evolution 2012, No. 1, pp. 97-108
- ↑ Kenny Travouillon & Matthew J. Phillips, 2018. Total evidence analysis of the phylogenetic relationships of bandicoots and bilbies (Marsupialia: Peramelemorphia): reassessment of two species and description of a new species . Zootaxa 4378 (2), 224-256.
- ^ IUCN Red List , accessed November 12, 2017.
- ↑ a b Driessen & Rose 2015, p. 120
- ^ Parks and Wildlife Service Tasmania: Foxes in Tasmania , accessed November 14, 2017.
literature
- Michael M. Driessen & Robert K. Rose: Isoodon obesulus (Peramelemorphia: Peramelidae) . In: Mammalian Species 2015, No. 47, pp. 112-123