Cercartetus Nanus Research Articles

Life history attributes of the threatened Australian snake (Stephen's banded snake Hoplocephalus stephensii, Elapidae)

Whether or not a species is threatened by habitat change is influenced by its life-history traits as well as by the nature and severity of the threatening process. Detailed studies of declining taxa can clarify reasons for their vulnerability, both in proximate terms (e.g., taxa with slow growth, delayed maturation, low fecundity and infrequent reproduction will be poorly suited to withstand increases in adult mortality rates) and in an evolutionary perspective (i.e., what attributes of the environment have favoured the evolution of certain life history traits?). We obtained data on life history traits during an intensive radio-tracking study on the threatened arboreal elapid snake Hoplocephalus stephensii from forest habitats of eastern Australia. Based on 39 field-collected specimens, these long, slender snakes (mean adult snout–vent length 73 cm, mass 114 g) feed predominantly on mammalian prey such as Bush Rats ( Rattus fuscipes) and Pygmy-possums ( Cercartetus nanus); but juveniles also take lizards. Foraging modes are diverse, from active searching through to ambush. Gape-limitation prevents snakes from ingesting adults of the most abundant local rodent ( R. fuscipes), limiting the snakes to specialise on sub-adult rats which are only seasonally available. Rates of feeding, growth and reproduction are low; for example, none of 21 wild-caught females was reproductive. However, snakes given access to abundant prey in captivity, rapidly gained in body condition, grew significantly, and subsequently reproduced. Litters consisted of a few (1–9), relatively large (25 cm snout–vent length, 7.5 g) offspring. The “slow” life-history traits that have contributed to endangerment of this taxon may include proximate as well as evolutionary responses to the low temperatures and limited prey availability in the forest habitat of H. stephensii.

Husbandry and breeding of the Eastern pygmy possum Cercartetus nanus: at Healesville Sanctuary

In 1998 6.4 Eastern pygmy possums Cercartetus nanus were placed in a large communal outdoor enclosure at Healesville Sanctuary. After 4 months two ♀♀ each had litters of four pouch young and a third ♀ had a single pouch young. The husbandry conditions which resulted in successful breeding in 1998 and 1999 are described and goals for future husbandry and research are outlined. At time of writing, and to the best of our knowledge, this is the first published record of C. nanus breeding in captivity.

Effects of habitat fragmentation on the demography, movements and social organisation of the eastern pygmy-possum (Cercartetus nanus) in northern New South Wales

A population of eastern pygmy-possums (Cercartetus nanus) was studied in northern New South Wales for almost 3 years. A total of 98 pygmy-possums was captured, of which 52 were captured only once. The sex ratio of the population did not differ significantly from parity. Mid-way through the study, 1.4 ha of the 4.0-ha study site was cleared. Pre-clearing capture rates in nest boxes averaged 33.5 ± 5.8 captures per 100 box checks per month, and the population was estimated by three methods to be at least 15–20 animals. There was no significant difference in body mass between adult males (23.7 ± 6.3 g) and adult females (27.1 ± 7.7 g). Males had significantly larger short-term home ranges (0.35 ± 0.14 ha) than females (0.14 ± 0.06 ha) and tended to move over greater distances each night. Breeding occurred from summer to early winter, and juveniles and sub-adults entered the population in autumn and winter. The mean number of pouch young was 3.9. The most likely minimum size at which juveniles left their mother was 9–11 g. Adult body mass and condition were highly variable over time, and did not appear to be related to either the breeding season or Banksia flowering. Fourteen pygmy-possums were found torpid during the study. Population troughs occurred in late winter and spring and were associated with low survival and/or seasonal migration, possibly linked to the cessation of Banksia flowering in July and the lack of alternative food sources at this time and/or increased use of nest boxes by Antechinus stuartii during late winter. Post-clearing, capture rates fell to 7.8 ± 1.6 captures per 100 box checks per month, the estimated population size fell to 5–8 animals, and there was an almost total lack of juvenile/sub-adult recruitment into the population. The results support concerns that the long-term survival of the eastern pygmy-possum in New South Wales is threatened by continued land clearing throughout much of its present range.

A comparison of the foraging behaviour of the eastern pygmy-possum (Cercartetus nanus) and nectarivorous birds in a Banksia integrifolia woodland

The foraging behaviour of a non-flying mammal, the eastern pygmy-possum (Cercartetus nanus) and nectarivorous birds was compared in a Banksia integrifolia woodland at Wilson's Promontory National Park, Victoria, Australia. Exclusion experiments performed previously in this woodland indicate that both non-flying mammals and nectarivorous birds are important pollinators of B. integrifolia (Cunningham 1991: Oecologia 87: 86-90). In this study it is shown that C. nanus and nectarivorous birds employ different foraging tactics. Nectarivorous birds tended to move further between trees (Χ = 8.16 ± 1.06 m) than C. nanus (Χ = 5.64 ± 0.75 m), although these differences were not significant. Nectarivorous birds were attracted to trees with a significantly larger number of inflorescences (Χ = 36.55 ± 2.84) than C. nanus (Χ = 18.65 ± 2.95), and visited a significantly greater number of inflorescences per tree (Χ = 4.24 ± 0.35) than C. nanus (Χ = 2.33 ± 0.22). Although the two pollinator groups were attracted to banksia plants by different cues, once in the plants they visited an equal proportion of the available inflorescences.

A comparison of the nitrogen requirements of the eastern pygmy possum, Cercartetus nanus, on a pollen and on a mealworm diet.

The eastern pygmy possum, Cercartetus nanus, is known to feed both on flower products and on invertebrates. This study compares its ability to meet its nitrogen requirements on pollen and on insect larvae. Captive C. nanus were fed diets in which nitrogen was provided either by Eucalyptus pollen or by the mealworm Tenebrio molitor. The apparent digestibility of the nitrogen from both sources was high, with a mean value of 76% for the pollen and 73% for the mealworms. This was much higher than would have been inferred from the common practice of measuring the percentage of empty pollen grains in fecal samples. The truly digestible maintenance nitrogen requirements of C. nanus on pollen were exceptionally low: 2.6 mg N d-1 compared with 9.5 mg N d-1 on mealworms. The value for pollen is the lowest yet recorded for any mammal. The difference between the requirements of C. nanus on the two diets appeared to be related to the composition of the mealworm and pollen protein. The biological value of the pollen nitrogen was exceptionally high for a plant protein, at 72%, whereas the biological value of the mealworm nitrogen was only 42%. This suggests that the amino acid composition of the pollen corresponded more closely to the requirements of C. nanus than the composition of the mealworm protein did. Pollen is an excellent source of nitrogen for C. nanus, and it should be considered as a potential nitrogen source for other flower-feeding animals.

Distribution and Status of The Eastern Pygmy Possum (Cercartetus nanus) in New South Wales.

The eastern pygmy possum (Cercartetus nanus) has a wide distribution in New South Wales (NSW), but is infrequently detected in fauna surveys. We collated available information on the distribution, habitat and detection rates for C. nanus in NSW from results of published and unpublished fauna surveys. These data, and those from the National Parks and Wildlife Service and Australian Museum databases, suggest that C. nanus populations are concentrated in south-eastern NSW and are sparsely distributed throughout the rest of the state. Several records extend the distribution of this species further west than currently shown by published distribution maps. Records show differences in habitat types occupied by C. nanus between south-eastern and north-eastern NSW. In south-eastern NSW, C. nanus occupies a range of habitats including heath, woodland and open forest, at a range of altitudes. In north-eastern NSW, C. nanus appears to be associated mainly with rainforest at high altitudes. Of the range of techniques available, nest boxes and Elliott traps positioned against flowering Banksia species are most effective at capturing C. nanus. Given the large survey effort and the small number of surveys detecting >I0 C. nanus, it appears that this species is rare throughout most of NSW. We recommend that C. nanus be considered for listing as a vulnerable species in NSW.

Survey of vertebrate fauna and habitats in a cypress pine-ironbark forest in Central-West New South Wales

Eighty-two species of vertebrates were recorded from an area of cypress pine and ironbark forest within Goonoo State Forest, located 42 Idiometres north-east of Dubbo. New South Wales. Grass-seed-eating birds were uncommon due to the lack of gasses within the forest. Small birds such as fairy-wrens, thornbills and warblers were only found where patches of dense shrub were found, usually where the canopy has been disturbed. Flowering ironbarks were found to attract a variety of bird species utilizing both the pollen and nectar as well as the insects that were attracted. Four threatened species (Glossy Black Cockatoo, Koala. Yellow-bellied Sheathtall Bat. Little Pied Bat) were recorded as well as a new range extension for the Eastern Pygmy Possum. Retention of ironbarks over 47.0 cm diameter at breast height is needed to preserve the presence of large tree hollows as well as eucalypt blossom sources within the forest.

Can Flower-Feeding Marsupials Meet Their Nitrogen Requirements on Pollen in The Field?

Two arboreal marsupials, the eastern pygmy possum (Cercartetus nanus) and the sugar glider (Petaurus breviceps) have exceptionally low maintenance nitrogen requirements on pollen diets. This study compares their nitrogen requirements with the density of Banksia pollen that is available in the Barren Grounds Nature Reserve, New South Wales, a site where both species are known to forage on Banksia inflorescences. The pollen density was sufficiently high that both species were capable of meeting their maintenance nitrogen requirements on pollen whenever Banksia spp. were in flower. C. nanus required a smaller proportion of its home range than P. breviceps to do so and pollen was likely to be of much greater nutritional significance to both species in winter than in summer. This corresponds closely with the results of field studies comparing the diets of these mammals at different times of the year. Pollen is an important source of nitrogen for flower-feeding marsupials but its importance will vary between species depending on the marsupial's requirements, its body size and on the quantity of pollen that is available.

Thermal relations of metabolic rate reduction in a hibernating marsupial.

We tested whether the reduction of metabolic rate (MR) in hibernating Cercartetus nanus (Marsupialia, 36 g) is better explained by the reduction of body temperature (Tb), the differential (delta T) between Tb and air temperature (Ta), or thermal conductance (C). Above the critical Ta during torpor (Ttc) of 4.8 +/- 0.7 degrees C where the Tb was not regulated, the steady-state MR was an exponential function of Tb (r2 = 0.92), and the overall Q10 was 3.3. However, larger Q10 values were observed at high Tb values during torpor, particularly within the thermoneutral zone (Q10 = 9.5), whereas low Q10 values were observed below Tb 20 degrees C (Q10 = 1.9). The delta T did not change over Ta 5-20 degrees C, although MR fell, and therefore the two variables were not correlated. Below the Ttc, Tb was regulated at 6.1 +/- 1.0 degrees C and MR increased proportionally to delta T. Our study suggests that MR in torpid C. nanus is largely determined by temperature effects and metabolic inhibition. In contrast, delta T explains MR only below the Ttc and C appears to affect MR only indirectly via changes of Tb, suggesting that delta T and C play only a secondary role in MR reduction during hibernation.

Patterns of co‐occurrence among arboreal marsupials in the forests of central Victoria, southeastern Australia

Abstract Patterns of co‐occurrence were examined among the suite of species of arboreal marsupials that inhabit the montane ash forests of the Central Highlands of Victoria, southeastern Australia. The data used in our analyses were counts of different species of arboreal marsupials derived from stagwatching surveys of 152 sites throughout the Central Highlands region. Our work investigated both the number of species that tend to occur together, as well as identity of the taxa in such associations. A total of eight different species of arboreal marsupials were recorded from field surveys of montane ash forests: Leadbeater's Possum (Gymnobelideus leadbeateri), Sugar Glider (Petaurus breviceps), Yellow‐bellied Glider (Petaurus australis), Greater Glider (Petauroides volans), Mountain Brushtail Possum (Trichosurus caninus), Feathertail Glider (Acrobates pygmaeus), Common Ringtail Possum (Pseudocheirusperegrinus), and Eastern Pygmy Possum (Cercartetus nanus). Large assemblages of taxa were rare and no sites supported the full array of species of arboreal marsupials– the maximum number of species recorded on a given 3 ha site was five. The results of our analyses indicated that if any one species of arboreal marsupials was present at a site, then on average 1. 5 other taxa will co‐inhabit that site. The exception was the Common Ringtail Possum. When this species was detected, few other arboreal marsupial taxa tended to be recorded with it. Principal Co‐ordinates Analysis showed that although combinations of animals comprised of either Mountain Brushtail Possum, Leadbeater's Possum, or Greater Glider were often recorded, there were no strong patterns in the identities of co‐occurring taxa. This finding, together with the result that most taxa in these forests typically co‐occurred with one or two other species, indicates that none of the arboreal marsupials inhabiting the montane ash forests of the Central Highlands of Victoria would be a good surrogate for (or ‘indicator’ of), the presence of the suite of other species in the assemblage.

Isolation and partial characterization of tammar wallaby luteinizing hormone and development of a radioimmunoassay.

Tammar wallaby (Macropus eugenii) luteinizing hormone (LH) was purified from pituitaries collected from wild and captive populations by salt sequential precipitation, ion exchange chromatography and gel filtration. Pituitary tissue (5 g) yielded 1.8 mg of purified wallaby luteinizing hormone (ME-14B), as verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). A heterologous radioimmunoassay has been developed for measurement of LH in plasma of marsupials using a monoclonal antibody raised against bovine LH (518B7). This assay system was able to measure basal LH concentrations in male and female tammars and detected a significant rise in plasma LH in response to oestradiol benzoate in female tammars and luteinizing hormone-releasing hormone (LHRH) in males. Parallel dose-response curves were also obtained from pituitary extracts from four other species of marsupial (brushtail possum, Trichosurus vulpecula; brown antechinus, Antechinus stuartii; kowari, Dasyuroides byrnei; and Eastern pygmy possum, Cercartetus nanus) in this assay, which suggests its usefulness in the measurement of LH in other marsupial species.

Native Australian Mammals – Eastern Pygmy Possum(xxiii)

Native Australian Mammals – Eastern Pygmy Possum(xxiii)

Foraging Behaviour of Marsupial Pollinators in a Population of Banksia spinulosa

Spool-and-line tracking was used to investigate the foraging behaviour of three marsupial species (Petaurus breviceps, Antechinus stuartii and Cercartetus nanus) which regularly visit inflorescences of the Australian native, Banksia spinulosa (Proteaceae). Although there were as many as 10 open inflorescences on a plant, 72% of movements by animals were to inflorescences on a different plant. Furthermore. nearly 70% of these movements were over 5 m in length, and movements ranged up to 59 m. Inter-plant movements were greater for P. breviceps than other species, particularly late in the flowering season when fewer inflorescences were available. This suggests that patterns of pollen flow in this population of B. spinulosa may vary spatially and temporally

An assessment of pollinator visitation to Banksia spinulosa

Abstract Remote photo‐monitoring of Banksia spinulosa inflorescences indicated that birds, mammals and insects were regular visitors. These included the sugar glider, brown antechinus, eastern pygmy possum, eastern spinebill, honeybee and several moth species. Eastern spine‐bills were recorded at all inflorescences monitored while visitation by other animals was more sporadic. Inflorescences were visited at least once every 24 h, and visitation frequency was approximately evenly distributed during the day and night. Examination of pollen tube growth from experimental treatments indicated that pollination success was similar from both nocturnal and diurnal visitors. However, nocturnal visitors were more effective at removing pollen from newly opened flowers. The behaviour of mammals at inflorescences was such that they would transfer much more pollen to flowers than other visitors, and probably contact receptive stigmas more often. Overall, mammals were considered to be slightly more effective pollinators than the more obvious daytime visitors, eastern spinebills. Although insects visited regularly, they were thought to be less effective at pollinating flowers than vertebrate visitors. Moths carried very little pollen, and the foraging behaviour of other insects was unlikely to promote much pollination.

Hibernation in the Eastern Pygmy Possum, Cercartetus-Nanus (Marsupialia, Burramyidae)

The pattern of torpor was examined in the eastern pygmy possum, Cercartetus nanus (21 g). Animals displayed torpor regularly in the laboratory, and the occurrence of torpor increased with decreasing air temperature (T(a)). At high T(a) (18-degrees-C) animals usually exhibited daily torpor, but torpor bouts of up to 2 days were observed occasionally. The duration of torpor bouts lengthened with a lowering of T(a) and the mean bout duration at T(a) = 5-degrees-C was 17.0 +/- 2.5 days. The minimum metabolic rate (measured as rate of oxygen consumption) of torpid individuals was 0.018 +/- 0.003 mL O2 g-1 h-1, which is less than 2% of the basal metabolic rate. The body temperature (T(b)) Of torpid animals fell to a minimum of 1.3 +/- 0.4-degrees-C. These results clearly demonstrate that Cercartetus nanus is a deep hibernator.

Small terrestrial mammals and bats of Melaleuca and Claytons, southwestern Tasmania

A survey of small terrestrial mammals and bats was undertaken in two areas of southwestern Tasmania: around Melaleuca, in sedgeland, scrub and woodland communities, and at Claytons in mixed forest. The density of bats was extremely low in comparison with populations in eastern Tasmania. The densities of Rattus lutreolusand Antechinus minimuswere greatest in sedgeland/scrub with a dense undergrowth. Pseudomys higginsi was only captured in mixed forest but is also present around Deny King's garden. Dasyurus viverrinus was most abundant in young sedgeland. Cercartetus nanus was present at both Clay tons and Melaleuca. No introduced rodents were trapped, but an outbreak of Rattus rattus had occurred previous to our study. No Mastacomys fuscus were trapped but they have been recorded in a previous study. Fire has an important influence on the composition and structure of the vegetation which, in turn, influences the composition and density of the mammal community.

Life-History of the Eastern Pygmy-Possum, Cercartetus-Nanus (Burramyidae, Marsupialia), in South-Eastern Australia

Populations of Cercartetus nanus were investigated in three areas of Victoria: two areas of Banksia woodland at Wilsons Promontory National Park and an area of mixed eucalypt forest with an under- storey of B. spinulosa at Nar Nar Goon North, east of Melbourne. Most births occurred between November and March, but in areas where the dominant Banksia sp. flowered in winter they took place year-round. Most females produced two litters in a year, but some produced three. Males were reproductively active throughout the year. Litter sizes ranged from two to six, with a modal size of four. Pouch life lasted 30 days and weaning occurred at 65 days. Growth was rapid, young became independent immediately after weaning, and matured as early as 4.5-5.0 months old. Maximum longevity in the field was at least 4 years.

The eastern pygmy possum, Cercartetus nanus (Marsupialia: Burramyidae), in the Australian Capital Territory.

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The Distribution of Arboreal Marsupials in Relation to Eucalypt Forest Types in the Eden (Nsw) Woodchip Concession Area.

Data collected during clear felling are collated and presented on the distribution of arboreal marsupials in 16 forest vegetation types (FVT) in 7 FVT groups. Eight species were included in the study: Petaurus breviceps, P. australis, P. norfolcensis, Petauroides volans, Acrobates pygmaeus, Trichosurus vulpecula, Pseudocheirus peregrinus and Cercartetus nanus. Most of the individuals reported were in the following 6 FVTs: swamp gum (characterized by Eucalyptus ovata); mountain gum (E. dalrympleana)/manna gum (E. viminalis); peppermint (E. radiata or E. dives); southern blue gum (E. maidenii, E. cypellocarpa or E. nitens); brown barrel (E. fastigata); and brown barrel/gum (E. cypellocarpa, E. nitens, E. maidenii, E. viminalis or E. dalrympleana). The results are discussed in relation to present forest management and forest clearing procedures in the Eden region. Forests about to be cleared for Pinus radiata plantations or for farmland on private property adjacent to State Forests are predominantly of types identified as of high value as wildlife habitat.

Transfer of Banksia-Spinulosa Pollen by Mammals - Implications for Pollination

Native mammals have been implicated by various authors as visitors to flowers of Australian plants in both eastern and western Australia, but few data are available to allow an estimation of their potential as pollinators. In the present study, Antechinus stuartii, Petaurus breviceps and Rattus fuscipes were regularly trapped in flowering Banksia spinulosa. A few Cercartetus nanus were also captured. Individuals of all species carried pollen on their fur. Pollen loads were greater on mammals which had been in traps for short periods, which suggests that mammals will groom pollen from their fur if left longer in traps. Therefore, pollen loads on foraging mammals have probably been dramatically underestimated by previous authors, and their potential to effect pollination may have been greatly underestimated. Furthermore, significantly more pollen was removed from flowers of B. spinulosa at night than during the day, suggesting the importance of nocturnal pollinators at this site.