Common striped possums (Dactylopsila trivirgata) inhabit Australia and New Guinea, including some nearby islands. In Australia they are restricted to northeastern Queensland, ranging from the tip of the Cape York Peninsula in the north to Mt. Spec in the south. They are widespread over this limited range, but is quite rare. In New Guinea they are much more common and distributed throughout the lowlands and foothills. (Broome and Lindenmayer, 2001; Handasyde and Martin, 1996; Smith, 1982; Van Dyck, 1979; Van Dyck, 1995)
Dactylopsila trivirgata is highly arboreal and lives almost exclusively in lowland tropical rainforest and adjacent woodlands. Within this habitat, it most commonly inhabits vine forests, riparian woodlands, and monsoonlands. Individuals are sometimes observed feeding in more open eucalypt (Eucalyptus spp.) and melaleuca woodlands.
The human alteration and destruction of rainforest may have several ecological impacts on this species. In fragmented landscapes, D. trivirgata requires habitat corridors that are connected to large tracts of continuous forest. These forests must also contain large trees over 30 cm DBH, because common striped possums need large trees with hollows for den sites. (Handasyde and Martin, 1996; Laurance and Laurance, 1999; Menkhorst, 2001; Van Dyck, 1979)
Dactylopsila trivirgata is a mid-sized possum with remarkable black and white coloration. The coarse pelage is characterized by 3 longitudinal variable black stripes. The middle stripe runs from the front of the head to the tip of the tail, while the lateral stripes start at the muzzle and course over the eyes and ears to the rump. Branches from the lateral stripes continue down the outside of each limb. The fur of juvenile and subadult animals displays sharp contrast between the black and white markings. The fur of adults exhibits more gradual transitions between black and white markings, and white areas become more grey with age. The distinct bushy tail is considerably longer than the body and is usually darker on top with the tip being either black or white.
Common striped possums have several unique morphological characters. They possess an elongated tongue and fourth finger, long incisors, and a rounding of the braincase. The fourth finger is nearly twice the length of the next, and the procumbent lower incisors of Dactylopsila have the greatest relative length of any possum. In addition, the first upper incisors project forward. All of these are most likely specialized feeding adaptations. The rounding of the braincase makes it possible for D. trivirgata to have the largest brain in relation to its body weight of any marsupial. (Fleay, 1942; Handasyde and Martin, 1996; Menkhorst, 2001; Rawlins and Handasyde, 2002; Van Dyck, 1995)
Not much is known about the mating systems of D. trivirgata. Observations suggest that there is intense male rivalry for breeding females. Males chase each other and make threatening, raucous vocalizations when in close contact. While coupled, both male and female repeatedly make loud, guttural vocalizations ("gar-gair, gar-gair") and intertwine and thrash their tails about. According to a single observation, copulation lasts approximately ten minutes. (Handasyde and Martin, 1996; Van Dyck, 1979; Van Dyck, 1995)
Limited research has been conducted on the breeding biology of D. trivirgata. Observations of mating in Australia have been made from February to August, and from January to October in New Guinea. This suggests a breeding seasonality. The breeding peak in Australia is June to July. Females have well-developed pouches with two mammae. They have one to two young, but almost always have two. The breeding interval for this species is not known. No detailed information has been documented on the development of young and the age to sexual maturity. (Handasyde and Martin, 1996; Smith, 1982; Van Dyck, 1979; Van Dyck, 1995)
The degree to which female common striped possums provide care for their young is not known. Males have not been documented to take part in providing for the offspring. Females will carry their offspring on their back after weaning, but it is not known for how long. The provisioning of post-weaning food to the young is not known either. (Handasyde and Martin, 1996)
Dactylopsila trivirgata is a nocturnal, arboreal insectivore. It is most active from 2100 hours to 0550 hours, and may spend up to 9 hours foraging each night. It forages in trees of different sizes, ranging from 10 cm DBH to 110 cm DBH. Dactylopsila trivirgata looks for food on living trees, dead snags, downed trees, and rotting logs. The species most often feeds in the cover of the forest, but has been observed feeding in adjacent openlands as far as 400 meters from the edge of the woods. It forages from the trunk to the canopy at least as high as 33 meters. While feeding and looking for food, striped possums move rapidly through the canopy jumping from tree to tree, accomplishing long-distance jumps with precison. Dactylopsila trivirgata has a lithe gait that gives limb movement a distinct 'rowing' motion. The feeding activity of D. trivirgata is very noisy as it rustles through the leaves, scratching and snorting. When it stops to feed, much debris falls to the forest floor and the loud sound of chewing and slurping has been noted by several researchers.
The adult male striped possum is generally solitary, except during breeding season. Males den alone. Juveniles and females often have been found denning together. Dactylopsila trivirgata dens during the day in dry leaf nests in tree hollows or on mats of epiphytes. Both males and females use a number of den sites, which are spread throughout their home range. Dens are always in forest trees that have a DBH over 30 cm. Cordia dichotoma is a common den tree species. (Handasyde and Martin, 1996; Nowak, 1999; Rawlins and Handasyde, 2002; Smith, 1982; Van Dyck, 1979; Van Dyck, 1995)
Home ranges of striped possums have been determined from radio-collared males. Younger males occupy a smaller home range than adult males. Subadult males may have a range as small as 5.2 ha and adult males may have a home range of about 21.3 ha. (Handasyde and Martin, 1996)
Striped possums make at least two types of vocalizations. They frequently call in a raspy guttoral "gar-gair, gar-gair" manner (described in "Reproduction," above). These vocalizations are followed by a social aggregation of two or three individuals. This call is suggested to play a role in the species' mating system and also seems to be used for other social groupings. The other type of call is a distress call that is used repeatedly when an animal feels threatened. The distress vocalization is a series of 5-6 creaking "frog-like" calls that decend in pitch ("erreeh"). This suggests that D. trivirgata may demonstrate a high degree of sociality.
The pungent scent of striped possums may be a predator deterent, but also might play a role in the social communication of the species. Further research is needed in this area. (Handasyde and Martin, 1996; Van Dyck, 1979)
Dactylopsila trivirgata is a generalist insectivore that eats primarily social insects, such as ants and termites, and wood-boring larvae of beetles and moths. It is more reliant on invertebrates than other members of the Petauridae, which is suggested not only by observations of foraging and stomach contents, but also by the simplicity and shortness of the digestive tract. In particular, the length of the caecum, an organ used in fermentation, is significantly shorter in D. trivirgata than in Petaurus breviceps and Gymnobelideus leadbeateri.
Striped possums eat insects from at least 8 orders, including Coleoptera, Hymenoptera, Lepidoptera, Isoptera, Blattodea, Orthoptera, Hemiptera, and Diptera. The insects that contribute most to the diet of striped possums are moth and beetle larvae, ants, termites, and crickets. The high frequency of wood-boring larvae and social insects in stomach samples suggests that D. trivirgata targets these high-energy foods. The fat content in these items is between 20 and 44%.
Many unusual adaptations allow D. trivirgata to be successful as an arboreal insectivore. It uses its forepaws to tap rapidly on wood to locate larvae. Once the insects are located, the powerful jaws and tooth orientation of striped possums make them great at excavating bark and wood from living and dead trees. Ant and termite eggs present in stomach contents suggests that D. trivirgata uses its jaws to break into insect mounds too. The striped possum has a dexterous elongated fourth finger that is used for collecting wood-boring larvae while it is excavating trees. The fourth digit is highly sensitive and some observations suggest that it is used to discriminate different vibration frequencies of various insects and larvae. The fourth finger is so sensitive that it represents 10% of the entire primary somatosensory area (SI) of the brain. This compares to a 4-5% representation of the SI for the fourth digit of northern quolls, Dasyurus hallucatus.
Pollen, nectar, flowers, sap, and fruit also contribute to the diet of striped possums. These items, however, comprise very little of the total diet. Interestingly, striped possums have been observed eating small mammals in captivity. (Fleay, 1942; Handasyde and Martin, 1996; Huffman, et al., 1999; Rawlins and Handasyde, 2002; Smith, 1982; Van Dyck, 1979; Van Dyck, 1995)
In New Guinea, indigenous peoples hunt D. trivirgata for food and skins. Amesthistine pythons (Morelia amethistina) also prey on striped possums. These pythons are common in the Australian habitat of D. trivirgata and may have a significant impact on young. Barking owls (Ninox connivens) and rufous owls (Ninox rufa) occupy the same areas and are known to feed on arboreal mammals, but have never been observed taking D. trivirgata.
In open areas, D. trivirgata is quite cryptic, due to its contrasting black and white coloration. The white markings make it difficult to make out when there are openings in the canopy that allow beams of light to penetrate.
Dactylopsila trivirgata possesses a foul, pungent odor. Its scent is said to be worse than other marsupial scents, which can be quite powerful. The purpose of the odor is not known, but it has been suggested that it is an enemy deterent. (Fleay, 1942; Handasyde and Martin, 1996)
Dactylopsila trivirgata is a host to many species of parasites. The first records of certain parasite species have been made from striped possums. Ixodes holocyclus Neumann and Ixodes cordifer Neumann are both parasites of D. trivirgata, along with at least two species of intranasal mites from the family Trombiculidae.
The indigenous people of New Guinea hunt D. trivirgata for meat and skins. The skins are used in certain cultural rituals. Striped possums are relatively common in New Guinea, and provide a good food source. (Handasyde and Martin, 1996; Rawlins and Handasyde, 2002)
In agricultural areas that border lowland rainforest, striped possums sometimes cause slight damage to sugar cane crops. They break into sugar cane stalks, but it is not known if they consume the sap or are simply looking for insects. (Smith, 1982)
This species is not yet globally listed.
Some preliminary genetic work has been done on D. trivirgata. The species has a karyotype with a diploid chromosome number of 18. The chromosome pairs 1 to 5 are submetacentric and pairs 6 to 8 are acrocentric. Data suggest that the karyotypes of the genus Dactylopsila are most similar to those of Dactylonax within the family Petauridae.
The probability of genetic bottlenecking during the invasion of the striped possum to Australia from New Guinea was quite high. However, recent genetic research has provided evidence that a significant bottleneck did not take place. Data from 9 females and 18 males indicate that Australian populations of striped possums have moderate levels of genetic diversity compared to other marsupials. (Murray, et al., 1990; Hansen, et al., 2003)
Matthew Wund (editor), University of Michigan-Ann Arbor.
Lucas Langstaff (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
animals that live only on an island or set of islands.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
chemicals released into air or water that are detected by and responded to by other animals of the same species
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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