Calaby's pademelon (Thylogale calabyi), also known as the alpine wallaby, is a species of marsupial in the family Macropodidae. It is endemic to Papua New Guinea. It is threatened by habitat loss and hunting.
Pademelons share many similarities in body structure to other marsupials through their pouch to care for their young and tail used for jumping. Calaby’s Pademelon prefers to forage in dense forested overgrowth and feeds on native leaves and grasses. The life span for this animal is up to 6 years in the wild. This species is considered iteroparous with the gestation period spanning 30 days. After birth, young stay in the mothers pouch for approximately 6 months. They are considered sexually mature at 14–15 months. There are many pademelon species, but Calaby’s pademelon is considered one of the most endangered due to its poorly distributed population from habitat loss. This species is classified as endangered by the IUCN.2 The arrival of human populations have been largely responsible for Calaby’s Pademelon’s dwindling population. Humans continue to be a threat to this species through hunting practices and deforestation. Conservation efforts have been created to help preserve the remaining populations left. Papua New Guinea has established the YUS Conservation Area.6 The reserve is an acronym named after three major rivers that run through it, the Yopno, Uruwa, and Som of the Huon Peninsula and works to conserve Calaby’s Pademelon. However, more research regarding population size, distribution, and trends of this species in Papua New Guinea is needed to better understand population dynamics of Calaby’s Pademelon.
Description and range
Pademelons are small marsupials of the genus Thylogale. Pademelons are some of the smallest of the family Macropodidae. The word ‘macropod’ means ’big foot’ which is a common trait found in marsupials. Most Macropods share the characteristics of hind legs larger than their forelimbs, large hind feet, and long muscular tails used for balance. Pademelons, wallabies, and kangaroos are very alike in body structure and originate from the same taxonomic family.1 Besides their smaller size, pademelons can be distinguished from wallabies by their shorter, thicker, and sparsely haired tails and ambulate by hopping just like wallabies. Male Pademelons grow to about 7 kg (15 lbs) which is roughly twice the size of their female counterpart which grow to about 4 kg (8 lbs). The length of the pademelon is 1 to 1.5 m (3.28 to 4.92 ft).1 Males are distinguishable by their defined muscles and body size due to their broad chest and forearms. Pademelons are characterised by their bilateral symmetry and are endothermic. Calaby’s pademelon has soft fine fur that is dark brown to grey brown on the dorsal side of the animal and reddish brown or lighter brown on the ventral side.5 Calaby’s pademelon currently has an area of occupancy of less than 500 km2 and is classified as ‘endangered’ by the IUCN.2
Ecology
The natural habitat of the pademelon is in dense forested undergrowth.4 They also make tunnels through long grasses and bushes in swampy areas. Pademelons are generally solitary animals and are the most active during the winter season. In winter, pademelons may gather in groups at feeding sites or basking sites. Pademelons are most active in late afternoon through to dawn. During the day, they rest in shallow depressions that are constructed nests lined with dead vegetation, shell fragments, feathers, and small pebbles.4 These marsupials thrive in dense eucalyptus forests and tend to live on the edge of the forest habitat. They stay particularly close to the forest edge when foraging at night. Each species differ slightly on what they feed on. T. calabyi (Calaby’s pademelon) feeds on fallen leaves, fresh leaves, ferns, orchids, grasses and berries.4 Their short tail and compact body are useful for maneuvering through dense vegetation. The pademelon breeding period is throughout the year. The gestation period for the female is 30 days while the ‘joey’ stays in the pouch for sixth and a half months after birth.4 The young are weaned from the mother around 7 or 8 months. Immediately after birth, the mother goes into oestrus and mates again. The lifespan of the Calaby Pademelon is around 5 to 6 years in the wild. They are considered sexually mature at 14–15 months. Pademelon predators are Tasmanian wolves (Thylacinus cynocephalus), Tasmanian devils (Sarcophilus harrisii), spotted tailed quolls (Dasyurus maculatus) and wedge-tailed eagles (Aquila audax). 5