Tarsipes rostratus
honey possum

Tarsipes rostratus is native to the south western tip of Western Australia, throughout the coastal-sand plain heathlands, which contains a diverse array plant communities. (Cooper and Cruz-Neto, 2009; Nagy, et al., 1995; Richardson, et al., 1986)

Preferred habitat of Tarsipes rostratus is banksia woodlands, which are rich in floral diversity. The overstory of banksia woodland habitat along the south western coast of Western Australia is dominated by Banksia attenuata (slender Banksia) and B. menziesii (firewood Banksia). Eucalyptus todtiana (coastal blackbutt), E. gomphocephala (Tuart), E. marginata (Jarrah), Allocasuarina fraseriana (Fraser’s sheoak), Nuytsia floribunda (christmas tree) and other Banksia species also occur, but far less frequently. Interspersed throughout the understory are various species in the families Proteaceae, Myrtaceae, Papilionaceae, and Epacridaceae (Maher et al., 2008). ("Restoration of banksia woodlands after the removal of pines Gnangara: evaluation of seeding trials.", 2008; Bradshaw and Bradshaw, 2002)

Tarsipes rostratus has grey fur that is brown on the dorsal side with a dark stripe starting from the nape of the neck extending down towards the base of the tail. It has white and yellow ventral pelage on its underbelly that becomes orange on its sides. The head is dorsoventrally flattened with an elongated snout that is approximately two and a half times longer than its maximum width. Tarsipes rostratus has a brush-tipped protrusible tongue that is equal in length to the head. With the exception of the incisors, which are enlarged, the dentition of T. rostratus is greatly reduced. Its hands and feet have rough pads, opposable and elongated digits, with nails that do not project beyond the toe-pads. It has a prehensile tail that is hairless on the ventral surface near the tip. Tarsipes rostratus is sexually dimorphic, with females being approximately a third heavier than males. Females range in mass from 10 to 18 g, have a body length ranging from 70 to 90 mm, and a tail that measures from 75 to 105 mm in length. Males range in mass from 6 to 12 g, have a body length ranging from 65 to 85 mm, and a tail that measures from 70 to 100 mm in length. Despite females being slightly larger, there is no difference in head length between the sexes. (Bradshaw and Bradshaw, 2007; Cooper and Cruz-Neto, 2009; Nagy, et al., 1995; Richardson, et al., 1986; Withers, et al., 1990)

Tarsipes rostratus has a higher basal metabolic rate (BMR) and field metabolic rate (FMR) than most other marsupials. It has an average body temperature of 36.6 C, which is much higher than the typical marsupial, and a BMR of 2.9 cm^3 oxygen/hour. When in torpor, if its body temperature falls below 5 degrees C it is incapable of exiting torpor. Daily energy expenditures range from 25 to 30 kJ/day, which classifies them as hypermetabolic. In order to meet their high energy demands, its diet consists primarily of pollen and nectar. (Bradshaw and Bradshaw, 2007; Cooper and Cruz-Neto, 2009; Nagy, et al., 1995; Richardson, et al., 1986; Withers, et al., 1990)

Tarsipes rostratus mates several times a year in a non-seasonal pattern. Females are polyandrous and have small litters, usually between 2 and 3 offspring but potentially up to 4, with multiple paternities. Female polyandry results in sperm competition between males. The testes of male T. rostratus are very large relative to their body size, weighing more than 4% of their total body mass. Their testes contain sperm that is larger than any other mammal. Males compete for estrous females and courtship is limited with no ongoing association after copulation. (Bradshaw and Bradshaw, 2002; Oates, et al., 2007; Rose, et al., 1997; Wooller, et al., 2000; Wooller, et al., 1999)

There is a strong association between reproductive success and diet in Tarsipes rostratus. Reproduction occurs during peak flowering periods when resources are abundant. In addition, breeding periods are affected by photoperiod and evidence suggests that the southern summer solstice triggers the first reproduction of the year. In general, breeding occurs from May to June, when day length begins to decrease and from September to October, when day length begins to increase. (Bradshaw and Bradshaw, 2002; Oates, et al., 2007; Wooller, et al., 2000; Wooller, et al., 1999)

Tarsipes rostratus has the smallest young of any mammal, which are reared in the pouch for about 60 days. By 60 days old young are highly mobile, fully-furred, and have eyes that are completely open. Young become sexually mature around 90 days and females often breed before their young disperse. Due to a period of embryonic diapause, gestation in T. rostratus lasts from 60 to 80 days longer than in other marsupials. Unlike other mammals, embyonic diapause in T. rostratus is not controlled by lactation. (Bradshaw and Bradshaw, 2002; Oates, et al., 2007; Wooller, et al., 2000; Wooller, et al., 1999)

Honey possums are relatively short lived, with a lifespan of 1 to 2 years. Lifespan of captive individuals has not been documented. (Wooller, et al., 1999)

Honey possums are nocturnal or crepuscular and are relatively nonsocial. In captivity, however, they huddle in large groups when they sleep but no such behavior has been observed in natural populations. There is little evidence of territoriality, however, females are dominant to males. (Bradshaw and Bradshaw, 2002; Rose, et al., 1997; Wooller, et al., 1999)

Females and males have individual home ranges but there is overlap between the home ranges of the different sexes. Male home ranges are much greater than those of females, primarily because they take refuge in a various locations throughout the day to avoid dominant females. Male honey possums can travel up to 114 m during the night to reach their feeding grounds. (Bradshaw and Bradshaw, 2002; Rose, et al., 1997)

Little is known of communication and perception in Tarsipes rostratus. In other possum species, it has been suggested that secretions from the holocrine gland are used to mark habitats and signal alarm. There is no evidence indicating that possums use scent marking to attract potential mates. (Woolhouse, et al., 1994)

Tarsipes rostratus consumes pollen and nectar from a variety of flowering plants. It is the only flightless animal that feeds exclusively on pollen and nectar. Large amounts of pollen and nectar are consumed from plants belonging to the families Proteaceae, Epacridaceae, and Myrtacae. Tarsipes rostratus prefers to forage on Banksia spp., which are large plants with widely separated and exposed inflorescences from the family Proteaceae. The Mediterranean climate of south-west Western Australia is prone to recurrent fires, which has a significant effect on the population density of T. rostratus. Areas that remain unburnt for longer periods of time have larger plants, which bear more inflorescences. Plants with more inflorescences are correlated with increased abundance of T. rostratus. Its feet and prehensile tail are used for climbing, while their forepaws with elongated digits are used to manipulate flowers during feeding. In order to acquire the necessary nutrients from nectar, a substantial quantity of fluid must be consumed. As a result of the high water content in their diet in conjunction with their inability to concentrate urine, T. rostratus frequently excretes high volumes of dilute urine. (Bradshaw and Bradshaw, 2002; Everaardt, 2008; Richardson, et al., 1986; Slaven and Richardson, 1988; Sumner, et al., 2005; Wooller, et al., 1999)

Aerial predators of honey possums, include barn owls (Tyto alba) and black-shouldered kites (Elanus caesuleus), and common terrestrial predators include red foxes (Vulpes vulpes) and feral cats (Felis domesticus). In certain parts of their range, Fitzgerald River National Park, other potential predators include tiger snakes (Notechis scutatus), southern monitors (Varanus rosenbergi), square-tailed kites (Lophoictinia isura), Australian kestrels (Falco cenchroides), brown falcons (Falco berigora), and boobook owls (Ninox novaeseelandiae). Honey possums are arboreal and are most commonly found in the lower canopy. As a result, the upper canopy likely provides shelter from aerial predators and being elevated off the forest floor likely decreases predation pressure from terrestrial predators. (Bradshaw and Bradshaw, 2002; Everaardt, 2003; Everaardt, 2008)

Honey possums are important pollinators for a number of different plants and are the principle pollinators of nodding banksia (Banksia nutans), which is common on the southern coast of Western Australia. (Wooller and Wooller, 2003)

There are no known positive effects of Tarsipes rostratus on humans.

There are no known adverse effects of Tarsipes rostratus on humans.

According to the IUCN Red List of Threatened Species, honey possums are a species of “least concern”. Due to their relative abundance and broad distribution, there are no major threats to their existence. However, bushfires can result in significant habitat loss. In addition, water mold (Phytophthora cinnamomi), which is prevalent in many high humidity environments, can cause plant pathogens that could decrease resource abundance for honey possums. Finally, feral cats may have a negative effect on honey possum abundance. (Friend, et al., 2008)