Добірка наукової літератури з теми "Petauroides volans"

The socio-ecology of Petauroides volans has been studied for subtropical and temperate populations, but not for the northern tropical subspecies, Petauroides volans minor. Data on the effects of a high population density on home ranges, time budgets and food-tree use were obtained by means of radio-telemetry. Three techniques were used to estimate home-range area (kernel, MCP and harmonic mean) and the kernel method was preferred. Estimates of home-range area (defined by the 95% kernel) gave mean values of 2.5 and 1.3 ha for males and females, respectively. Broad overlap of home ranges of males was observed, which has not been reported previously for populations of P. volans. Behaviour patterns for males and females were similar to those in previous studies, although the mating system may differ, possibly because of the high population density. Dietary patterns were similar to those previously reported for this species, the most important food items being young leaves and flower buds of particular eucalypt species, notably Eucalyptus acmenoides.

The efficacy of spotlighting as a field survey technique for detecting the greater glider (Petauroides volans) was assessed by comparing the precise location of radio-tracked animals with locations determined simultaneously from spotlighting searches. Radio-collars were fitted to 20 greater gliders in three eucalypt patches embedded within an extensive radiata pine (Pinus radiata) plantation near Tumut in south-eastern New South Wales. Our success rate for detecting collared animals was low, even when survey effort was increased. These findings suggest that spotlighting underestimates actual population size. A further, properly designed study, in different forest types is needed to provide precise estimates of the magnitude of the bias in counts of P. volans obtained by spotlighting.

Amounts of carbon dioxide (CO2) produced by caged greater gliders were measured simultaneously by means of potassium hydroxide absorption, and by the low-level, doubly labelled water method, which incorporated a gas isotope ratio mass spectrometer for determining the low oxygen isotope enrichments. The two methods yielded significantly different values, but doubly labelled water underestimated CO2 production by only 8.3% on average, and this error is in the range of mean errors found in previous validation studies where no significant differences existed. In addition, we tested procedures designed to reduce the costs of using the doubly labelled water method, by streamlining field and laboratory procedures for sample handling and processing.

This paper examines home-range attributes of 40 greater gliders (Petauroides volans) in five patches of remnant eucalypt forest surrounded by stands of radiata pine (Pinus radiata) near Tumut in south-eastern Australia. Fixed-kernel smoothing methods were used to estimate home-range size for P. volans. For males, home-range size varied from 1.38–4.10 ha (mean = 2.6 ± 0.8 ha, n = 12) and was significantly larger (P < 0.05) than for females (1.26–2.97 ha, mean = 2.0 ± 0.6 ha, n = 11). Home-range size increased significantly with increasing patch size and reduced patch population density. Thus, small patches had more animals per unit area with smaller home ranges and greater home-range overlap. Our findings illustrate flexibility in the use of space by P. volans. Such results have not previously been reported for P. volans or any other species of arboreal marsupial. Considerable home-range overlap (at 95th percentile isopleth level) was observed between male and female P. volans. Pairs of females also exhibited home-range overlap. Males tended to maintain home ranges exclusive of other males, although some shared common areas. Contrary to the large variations observed in home-range area, core areas (50th isopleth) remained relatively constant, regardless of patch size, population density or sex. This may indicate that core areas are an essential requirement for individuals and resources they contain cannot be shared with congeners.

Variations in diploid chromosome number, due to the presence of B chromosomes, are found within the distribution of P. v. volans. B chromosomes vary in number between one and eight per animal, are mitotically stable in various body tissues and, unlike the Y chromosome in male P. v. volans, are not eliminated from bone marrow cells. Animals possessing B chromosomes have a distinct distribution, and it appears that a stable equilibrium between the forces of B chromosome accumulation or elimination is operating in those populations possessing these chromosomes.

Water flux and metabolic rate were measured using a low-level, doubly-labelled water technique in eight free-living greater gliders, Petauroides volans which were maintaining constant body masses at about 1 kg in eucalypt forest near Maryborough, Queensland. Mean water influx was 88.0�3.2 mL d-' and mean metabolic rate was 25.1 L C02 d-' or 520 kJ d-'. These arboreal folivores have field metabolic rates and water influx rates that are 96% and 71% respectively of those predicted for a herbivorous marsupial of their body mass. Assuming that faecal energy losses were 43% of gross energy intakes and that urinary energy losses were 15% of digestible energy intakes, the gross energy intake of the animals was about 1130 kJ d-'. Animals would need to eat between 45 and 50 g of dry matter daily to satisfy these energy requirements. Based on these results, a preliminary energy budget for greater gliders has been proposed.

Night-time use of feed trees by 40 radio-collared individuals of the greater glider (Petauroides volans) was recorded within five remnant patches of eucalypt forest near Tumut in south-eastern Australia. Radio-collared animals were observed making 663 night-time visits to 433 trees. For these observations, we recorded the number of visits by an animal to each tree, the number of different animals using each tree, the characteristics of trees that animals used, and the category of activity or behaviour displayed by animals (classified as feeding, perching, and moving). We found no evidence of a significant difference in patterns of behaviour between male and female P. volans in their night-time use of trees within remnant patches, regardless of patch size or population density. There were few records of animals (4%) from the radiata pine (Pinus radiata) plantation that surrounded the eucalypt remnants, although 20 observations were made of P. volans feeding on the young male cones and buds of this introduced tree species. There was evidence of preference for feeding in ribbon gum (Eucalyptus viminalis), mountain gum (E. dalrympleana) and narrow-leaved peppermint (E. radiata), with 72% of feeding observations of P. volans coming from these three tree species. Animals were generally solitary and spent most of the night feeding and perching in the upper canopy. Most trees were used by a single individual, with 96% of observations being of a single animal in a tree. The limited number of cases of sharing and co-use of trees were generally between an adult male and adult female (assumed mates), and females and their young. The probability that a tree was used increased with the average size of a tree (a composite measure of diameter, height and crown features) until approaching an asymptote of 1.0, i.e. all large trees were used. The number of visits a tree received from P. volans also was positively related to the measure of its size.

L.W. Braithwaite and co-researchers hypothesised that the population density and diversity of the arboreal marsupial fauna of the eucalypt forests near Eden, New South Wales were primarily determined by the concentrations of nitrogen, phosphorus and potassium in the mature foliage of the eucalypts. I investigated this hypothesis in relation to the Greater Glider Petauroides votans. The first main objective of my study was to examine why population densities of P. votans are low in eucalypt forests with relatively low concentrations of nutrients in their mature foliage and high in eucalypt forests with relatively high concentrations of nutrients in their mature foliage. Initially, several a priori hypotheses were proposed that could account for the observed population densities of P. votans in these forests, and these were tested at two forest sites in south-eastern N.S.W. by studying and comparing the ecology of P. votans at these sites. One site of 24.6 ha at Wadbilliga carried four species of eucalypt (E. dalrympleana, E. fastigata, E. radiata, E. viminalis}. These had high concentrations of N and P in their mature foliage when compared to the range of values known for foliar N and P in this genus. The other site of 50.1 ha was at Morton and consisted of 40.3 ha of two species of eucalypts, E. gummifera and E. piperita, which formed 'forest type A'. Two smaller areas, termed 'forest types B and C', within the Morton site also supported other eucalypt species, E. sieberi at forest type B and E. consideniana, E.pellita and E. sieberi at forest type C. The nutrient concentration in the mature foliage at Morton was generally lower than at Wadbilliga. Basal area and height of the eucalypts, and the relative concentrations of N and P in their mature foliage suggested an apparent decline in forest site foliage suggested an apparent decline in forest site productivity from Wadbilliga through Morton forest types C, B and A. The change in the ratio of Symphyomyrtus to Monocalyptus eucalypts across these forests also was consistent with the presence of a decline in productivity. Many aspects of the social organisation of P. volans were related to this decline. There productivity from Wadbilliga through Morton forest types C, B and A. The change in the ratio of Symphyomyrtus to Monocalyptus eucalypts across these forests also was consistent with the presence of a decline in productivity. Many aspects of the social organisation of P. volans were related to this decline. There was a marked difference in the distribution of resident adult P. volans at the two sites. Gliders at Wadbilliga had a relatively even distribution across the site and most of the site was permanently occupied. In contrast, gliders at Morton had an extremely clumped distribution. The majority of the site was unoccupied (forest type A) and resident animals were restricted to forest types B and C which appeared to be the only favourable habitats within the site. The population density of P. volans did not appear to be related to forest site productivity. Based on the entire area of the site, the number of resident adult P. volans per hectare was 0.18 at Morton; but on the basis of the area of forest apparently suitable for occupation the population density of gliders was 0.89 animals ha-l in forest type B and 1.67 animals ha-l in forest type C. This was then higher than the population density of P. volans at Wadbilliga (0.88 animals ha-l). In contrast, the annual fecundity of the populations of P. volans was related to forest site productivity. Resident animals at Wadbilliga and Morton forest type C successfully raised young during each year of the study but those in Morton forest type B did not, although their social cycle was comparable to gliders elsewhere. Neither Wadbilliga nor Morton appeared to have experienced major disturbances such as wildfire in recent years, and neither predation nor the availability of den sites appeared to influence the distribution of resident gliders. The majority of data on the behaviour and feeding ecology of P. volans were consistent with the following observations. The observed distribution and fecundity of P. volans in each forest appeared to be related to the availability of high-quality food and this factor was an important determinant of habitat quality. At Morton, for example, the amount of such foods in forest type A was considered to be insufficient to support resident P. volans. Although high-quality food was available in forest type B, the amount of this food, at least during the study, was insufficient for successful production of offspring by resident P. volans. The foraging behaviour of P. volans at both sites differed little. All gliders attempted to maintain a high intake of new leaf growth in their diet in all seasons so foraging was closely related to the spatial and temporal availability of this food. Female P. volans at Wadbilliga and Morton forest type C, for example, spent less time foraging and were able to meet the majority of their annual food requirements from a smaller area of forest compared to females in Morton forest type B. As a consequence, females at Wadbilliga and Morton forest type C also probably expended less energy foraging compared to those in Morton forest type B. These data, combined with those on forest site productivity and eucalypt phenologies, were consistent with the hypothesis that the availability of high-quality food was higher at Wadbilliga and Morton forest type C compared to that at Morton forest type B and particularly Morton forest type A. P. volans consistently foraged for and browsed eucalypt foliage that was high in nitrogen concentration. However, my data were insufficient to implicate foliar nitrogen as the ultimate factor determining browse selection by this species. Clearly, many other foliar constituents, either independent of or in association with nitrogen, may be implicated in browse selection and influence the dietary quality of foliage for P. volans. New data on aspects of the ecology of P. volans that are relevant to its management are presented. A polygyny threshold model that may account for all of the known data on the distribution, population fecundity and mating associations (i.e. monogamy or facultative monogamy) exhibited by P. volans throughout its range is given. Application of this model may have considerable potential for identifying the high-quality habitat required by P. volans. Finally, areas warranting further research are outlined