Tarsipes rostratus, Gervais & Verreaux

Russell A. Mittermeier & Don E. Wilson, 2015, Tarsipedidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 566-573 : 573

Honey Possum

Tarsipes rostratus

French: Possum a miel / German: Honigbeutler / Spanish: Falangero mielero

Other common names: Honey Mouse

Taxonomy. Tarsipes rostratus Gervais & Verreaux, 1842 ,

Swan River , Western Australia, Australia.

This species is monotypic.

Distribution. SW Western Australia, from Geraldton Sandplains to Esperance Plains.

Descriptive notes. Head-body 6.5-8.5 cm (males) and 7-9 cm (females), tail 7-10.5 cm (both sexes); weight 7-10 g (males) and 8-16 g, but up to 20 g (females). Some female Honey Possums are 100% heavier than any male. Both sexes are gray to reddish-brown dorsally and buff to cream ventrally. Three longitudinal dorsal stripes run from snout to base oftail; darker central stripe is chocolate color, and lateral stripes are rufous. Honey Possums have long, pointed snouts and long, protrusible tongues. Grasping hands and feet have opposable digits and nails, not claws.

Habitat. Heathlands and shrublands, especially near the coast. Preferred habitat of the Honey Possum has a high diversity of nectar-producing plants, especially banksias ( Proteaceae ).

Food and Feeding. The Honey Possum eats only floral nectar and pollen, with much reduced dentition and jaws too weak to bite or chew. It appears to be the only nonflying mammal restricted to this diet. Even in areas with high plant diversity, the Honey Possum normally feeds only on flowers of 7-10 plant species, mostly in the family Proteaceae (banksias and allies). Although actual species of food plants vary from place to place, at each location, they flower sequentially throughout the year, leaving no time when nectar and pollen are not available. In less optimal habitats, Honey Possums are more opportunistic relative to the flowers they visit.

Breeding. Young are born throughout the year, and sexually mature individuals breed asynchronously. Males and females are sexually mature when only one-half of their adult weight, ¢.6 months after birth. Thereafter, almost every female carries young in her pouch for the remainder of her brieflife (c.1 year), some producing several successive litters in a year. Neonatal Honey Possum is the smallest mammal known (3-6 mg). Although four young are born, normally only 2-3 survive to leave the pouch c.2 months after birth, becoming independent a few weeks later at 2-3 g. Males have the longest sperm known for any mammal (0-36 mm) and testes that weigh 4-2% of total body mass, both apparently the result of strong competition to sire offspring. Most young in a litter have different fathers due to multiple mating. Coupled with 95% heterozygosity (28-50 alleles/locus), this leads to great genetic variability, even during population bottlenecks.

Activity patterns. Honey Possums are active from dusk to dawn or under daytime clouds, especially in winter. Their eyes are adapted to low light rather than full dark, with color vision suited to twilight, and their large binocular overlap aids depth perception when climbing and jumping.

Movements, Home range and Social organization. Honey Possums are essentially solitary and are relatively sedentary in favorable habitat where densities can reach 70 ind/ ha. They live and feed alone in home ranges that average 980 m* and overlap greatly. Home ranges of adult males average 1280 m*, home ranges of adult females average only 700 m®. They are not territorial although large females tend to avoid each other and are more sedentary than the smaller males. Some males moved 1-3 km over 1-2 weeks especially in habitat that is marginal or affected by adverse conditions (e.g. drought or fire).

Status and Conservation. Classified as Least Concern on The IUCN Red List. Honey Possums are the most abundant and widespread mammal in some national parks in south-western Australia. Their distribution has contracted substantially from clearing of native vegetation for agriculture, although this has largely ceased. Urban development continues to remove former habitat, such as woodland of Banksia (Proteaceae) . Changes to fire regimes and lower rainfall in south-western Australia resulting from global climatic changes pose threats to the Honey Possum. Preferred food plants of Honey Possums are also acutely susceptible to a waterborne fungal disease now widespread throughout their distribution.

Bibliography. Arrese et al. (2002), Bradshaw, FJ. & Bradshaw (2001), Bradshaw, FJ. et al. (2004), Bradshaw, S.D. & Bradshaw (1999, 2002, 2012), Bradshaw, S.D. et al. (2007), Chapman & Newbey (1995), Collins et al. (1987), Edwards & Westerman (1995), Friend (1993), Garavanta et al. (2000), Hayman & Sharp (1982), Kavanagh et al. (2004), Kirsch et al. (1997), Kratzing (1982), Landwehr et al. (1990), Mahoney (1981), Nagy et al. (1995), Nilsson et al. (2004), Oates et al. (2007), Renfree (1980), Renfree et al. (1984), Richardson et al. (1986), Rosenberg & Richardson (1995), Russell (1986), Russell & Renfree (1989), Scarlett & Woolley (1980), Slaven & Richardson (1988), Spencer & Bryant (2000), Withers et al. (1989), Wooller & Richardson (1992), Wooller & Wooller (2003, 2013), Wooller, Renfree et al. (1981), Wooller, Richardson & Bradley (1999), Wooller, Richardson & Collins (1993), Wooller, Richardson, Garavanta, Saffer, Anthony & Wooller (1998), Wooller, Richardson, Garavanta, Saffer & Bryant (2000), Wooller, Russell & Renfree (1984), Wooller, Russell, Renfree & Towers (1983), Woolley & Scarlett (1984), Yamada et al. (1989).

Figures

Honey Possum

Distribution. SW Western Australia, from Geraldton Sandplains to Esperance Plains.