Radiotracking and live‐trapping were used to describe spacing patterns of Dasyurus geoffroii along the Murray River in Western Australia. Both sexes are essentially solitary, and occupy numerous dens which define stable core areas. Female core areas typically showed little or no mutual overlap, suggesting that females are intrasexually territorial. As an exception to this, a non‐dispersing daughter may share her mother's core area and successfully rear young there. Transient females were rarely encountered, and vacant female core areas were eventually occupied by juveniles known to have been born on the study area. Male core areas were much larger than those of females, and overlapped broadly with those of other males as well as females. In captivity, females deposit scent by cloacal dragging in response to odours left by foreign conspecifics, and both sexes tend to defecate at sites already containing faeces. In the wild, faecal aggregations occurred throughout the areas used by Dasyurus, but were especially well developed in places where animal movements were likely to be concentrated, such as paths and river crossing points.
Phascogale tapoatafa, an arboreal carnivorous marsupial, is the largest mammal in which an obligate yearly die-off of all males occurs. The species is one of the most widespread of Australian marsupials, being found in tropical, subtropical and temperate forests and woodlands of Australia. Its breeding season varies little throughout this range, with most births occurring in July. In three Victorian populations, 2-year-old females typically gave birth earlier than first-year females, births were spread on average over 15 days, and, in some years, occurred two weeks earlier than average. Modal litter size equalled the number of teats (8), but litters of 1-6 young comprised 29% of the sample (n = 45), and litter size averaged 6.6 young. The sex ratio of litters produced by second-year females was significantly male-biased (0.62); that of first-year females was 0.48. When juveniles first released the teats (c. 48 days of age), they weighed about 4 g. Weight gain by captive juveniles was more rapid than that of wild conspecifics prior to weaning, but skeletal growth rate and morphological development were similar. Total lactational investment by P. tapoatafa is much greater than expected for a dasyurid of its size (wild litters at weaning average 313% of maternal weight; captive litters average 370%). The high mortality of wild adult females during lactation may reflect this energetic drain.
When juvenile Phascogale tapoatafa first release the maternal teats and are left in the nursery nest (c. 48 days of age), they lack fur, weight about 4 g, and are poikilothermic. Thermoregulation of wild litters was measured using a temperature-sensitive radio-transmitter inserted into the huddled litter after the mother's departure at night. On cold nights (less-than-or-equal-to 10-degrees-C), juveniles lose heat rapidly in the absence of their mother, with litter temperatures declining to an average of 6-degrees-C in 4 h. Litter temperatures of 3-degrees-C were common. Maternal attendance (incubation) is frequent and of long duration during the early-nesting period, then decreases as juveniles acquire fur and develop endothermy. The mother contributes to litter thermoregulation and security by constructing a large nest of bark, feathers and fur in a tree cavity with a small entrance hole.
Growth and development of six captive litters of D. geoffroii were monitored at 1-5 day intervals from birth until they were left in dens at about 62-72 days of age. Two neonates were 4.4 mm long and weighed an average 11 mg. By the age of 63 days, juvenile weight had increased 1500-fold, to an average of 16.7 g. Growth of crown-rump length (from 0-40 days) and the square root of head width (from 8-65 days) is linear with respect to time. Wild D. geoffroii were first observed to be left in dens at the age of 62 days, soon after outgrowing the pouch. Wild and captive growth rates appear similar through the first half of pouch life. At older ages, wild litters generally grew more slowly than captive litters; wild litters belonging to thin mothers grew more slowly than litters with medium-weight mothers, which in turn grew more slowly than litters with fat mothers.
The difficulty of observing the behaviour of cryptic, nocturnal carnivorous marsupials (Dasyuridae) in the wild has created a reliance on laboratory studies for the analysis of social interactions. Behavioural data on wild Phascogale tapoatafa suggest that previous interpretations may be biased by laboratory confinement. The play of juvenile P. tapoatafa entailed brief, non-contact chases, which apparently provide social practice prior to the solitary, post-dispersal life of adults. Interactions between wild adults very rarely included physical contact. Most encounters (63%) comprised chases, of which only female-female interactions commonly displaced the chased animal more than 3 m. Wild females readily deterred males from approaching closely by vocal threatening, even during the peak of the breeding season, so that forced copulation (as reported in captive dasyurids) was unlikely. Scent-presentation experiments suggested that sternal marking by males was intersexual communication, and may serve, along with intersexual chases, to familiarise females with future mates.
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