Cercartetus Nanus Research Articles

Response of eastern pygmy possums, Cercartetus nanus, to selective logging in New South Wales: home range, habitat selection and den use

Context Selective logging of native forests creates a mosaic of disturbance histories; however, little is known about how different taxa respond to such a mosaic. Aims We followed adaptive-management principles to test logging and burning impacts on eastern pygmy possums, Cercartetus nanus (Geoffroy and Desmarest, 1817), by undertaking a large-scale field experiment that coincided with harvesting. We predicted that home range would increase after logging because of a reduction in resources (food and/or dens) and because hollows suitable for denning would decrease, resulting in greater use of unlogged patches and alternate dens. Methods We radio-tracked C. nanus in a before-and-after logging experiment to investigate home range, habitat selection and den use. We tracked 50 possums, some individuals for a maximum of 8 months, within control, recently logged and regrowth (5 years since logging) sites. Key results Home ranges were variable (0.04–19.5 ha), with males having significantly larger home ranges. We were unable to detect a difference in home-range size between controls and the first year after logging and burning, or regrowth 5 years after logging. Home ranges comprised a mosaic of disturbed and undisturbed areas, and possums did not avoid logged habitat in their home ranges, indicating that logging did not significantly influence habitat selection. We suggest that possums were not sensitive to selective logging and burning because nectar-producing plants are adapted to fire disturbance and because a variety of den sites were used, most commonly in tree hollows and fallen logs, which were commonly left as logging residue. Indeed, possums frequently denned in logged patches, both recently after logging (63% of dens) and in regrowth 5 years after logging (76% of dens). Counts of fallen hollow logs at each site indicated that their density was not reduced by logging, with regrowth sites having the greatest abundance of logs (260 ha–1). Conclusions The mosaic of disturbance created by selective logging operations did not negatively affect home range or den selection of C. nanus. Implications Ecologically sustainable logging practices that include a range of mitigation measures to protect biodiversity can be compatible with the management of threatened species. Assessment of the effectiveness of these methods often will rely on scientific research.

Summer and winter torpor use by a free-ranging marsupial

Torpor is usually associated with low ambient temperatures (Ta) in winter, but in some species it is also used in summer, often in response to limited food availability. Since the seasonal expression of torpor of both placental and marsupial hibernators in the wild is poorly documented by quantitative data, we investigated torpor and activity patterns of the eastern pygmy-possum Cercartetus nanus (17.4g) over two seasons. We used radio telemetry to track animals during winter (n=4) and summer (n=5) in a warm-temperate habitat and found that torpor was used in both seasons. In winter all animals entered periods of short-term hibernation (from 5 to 20days) containing individual torpor bouts of up to 5.9days. In summer, torpor bouts were always <1day in duration, only used by males and were not related to daily mean Ta. Pygmy-possums entered torpor at night as Ta cooled, and rewarmed during the afternoon as Ta increased. Individuals interspersed torpor bouts with nocturnal activity and the percentage of the night animals were active was the same in summer and winter. Our study provides the first information on torpor patterns in free-ranging C. nanus, and shows that the use of torpor throughout the year is important for energy management in this species.

Does nest box design influence use by the eastern pygmy-possum?

Managing the availability of shelter sites is central to the conservation of vertebrate wildlife dependent on tree hollows (cavities) because hollow abundance has been reduced in many landscapes and trees do not typically acquire hollows until they are at least 100 years old. Artificial hollows (nest boxes) provide one option to offset local shortages in tree hollows. However, knowledge of preferred designs is required for this to be effective. We investigated nest box preference by the eastern pygmy-possum (Cercartetus nanus), a small marsupial recognised as threatened across part of its geographic range in eastern Australia. We installed nest boxes of four different designs in each of 30 plots where tree hollows were scarce. Designs showed no significant difference in thermal profile. We captured 223 adult and subadult pygmy-possums within 78% of the 120 boxes. Breeding females used boxes more frequently than adult males and showed a preference among the designs whereas males did not. Females favoured plywood nest boxes over a PVC design offering a horizontal cavity. Use of the PVC design increased when repositioned to present a vertical cavity. Thus, breeding females are selective of the cavities used to rear young, which may limit local population size.

Prevalence of threatened native species in canid scats from coastal and near-coastal landscapes in south-eastern Australia

Predator scat analysis was used to infer the potential impact of wild dogs (Canis lupus dingo, C. l. familiaris and hybrids of the two) on threatened native terrestrial mammals in coastal and near-coastal southern New South Wales, Australia. Prey items recorded in wild dog scats were compared with those occurring in scats of the red fox collected at the same study sites. Six threatened mammal species were recorded in either wild dog or fox scats: eastern pygmy possum, grey-headed flying fox, long-nosed potoroo, southern brown bandicoot, white-footed dunnart and yellow-bellied glider. The prevalence of these threatened species in fox scats was significantly higher than in wild dog scats. Otherwise, wild dogs mostly consumed larger prey items such as swamp wallabies and wombats whereas foxes more heavily preyed on small mammals such as antechinus and rats. Our results suggest that foxes are the major threat to threatened mammal species in the study region. Land management agencies in south-eastern mainland Australia should therefore focus on controlling foxes for biodiversity gain.

Effects of nest use, huddling, and torpor on thermal energetics of eastern pygmy-possums

Eastern pygmy-possums (Cercartetus nanus) are known to be conservative with energy use probably because they rely on food that varies in availability. We quantified how nest use, huddling, and torpor contribute to a reduction of energy expenditure in C. nanus during mild cold exposure. In comparison to normothermic resting C. nanus at the same ambient temperature, nest use reduced energy expenditure on average by ~17%, huddling as a pair in a nest by ~50%, whereas torpor, which was employed by all seven individuals, lowered energy expenditure by &gt;95%. Our study shows that while all energy-conserving strategies employed by these possums can contribute significantly to reducing energy expenditure, torpor is by far the most effective because it not only reduces thermoregulatory energy costs, but also energy expenditure required for maintenance processes.

Cercartetus nanus (Diprotodontia: Burramyidae)

Abstract Cercartetus nanus (Desmarest, 1817) is a burramyid commonly called the eastern pygmy-possum. It is 1 of 4 species in the genus Cercartetus, which together with Burramys parvus form the marsupial family Burramyidae. This species is endemic to southeastern Australia and occupies a range of vegetation types, but Banksia woodland is probably preferred habitat. This species is notable for its longevity, ability to hibernate, and its likely role as an important pollinator of a range of large-flowered plants. This species is of conservation concern in several Australian states, where it is threatened by habitat loss, inappropriate fire regimes, and introduced predators.

Distribution, habitat and conservation status of the Eastern Pygmy-possumCercartetus nanusin Queensland

Reliable modern records of the Eastern Pygmy-possum Cercartetus nanus in Queensland were collated from various sources (including databases and previous reports) and a map of potential C. nanus habitat was generated based on an analysis of regional ecosystems and expert decision rules. Modern records of C. nanus (collected between 1936 and 2002) are confined to the far south-east of the State, from or adjacent to Lamington and Mt Barney National Parks. Only 13 modern records exist and all but one are from or above 750 m elevation. Attention is also drawn to the existence of Late Pleistocene fossil records of C. nanus from Russenden Cave, Viator Hill, in south-east Queensland, which may suggest that a long-term range contraction has occurred. Currently the status of C. nanus is officially ‘least concern’ under the Queensland Nature Conservation (Wildlife) Regulation 1994. A reappraisal of the species' conservation status in this State was undertaken using the available evidence and the World Conservation U...

Effects of food and fire on the demography of a nectar‐feeding marsupial: a field experiment

AbstractAnimals that specialize on nectar can be expected to face shortages of energy at times or in places where floral resources fade. Using a nectar‐feeding marsupial, the eastern pygmy‐possum Cercartetus nanus as a model, we predicted that animals would respond rapidly to an artificial energy supplement by showing improved body condition and increased local abundance. We also tested the hypothesis that responses would be more pronounced in burnt than in unburnt habitats due to the expectation that food would be limiting after fire. Energy was added in the form of sugar solution to two burnt and two unburnt woodland sites on the New South Wales coast, but not to two sets of equivalent control sites. The responses of pygmy‐possums were compared between sites a month before and a month after supplementation during early autumn when flowers were diminishing. The energy supplement increased on‐site immigration and a tail‐fat index of body condition, but had no overall effect on the abundance or mean body mass of pygmy‐possums. There was no effect of habitat; floral abundance was equal across sites. The results show that C. nanus responded rapidly to the energy supplement, and indicate that animals monitor shifts in the resource base continuously. Similar resource tracking abilities have been demonstrated previously in more mobile nectar‐feeders, such as honeyeaters and bats. We suggest that such abilities should be generally advantageous in any species that depend on ephemeral resources.

Yearlong hibernation in a marsupial mammal

Many mammals hibernate each year for about 6 months in autumn and winter and reproduce during spring and summer when they are generally not in torpor. I tested the hypothesis that the marsupial pygmy-possum (Cercartetus nanus), an opportunistic nonseasonal hibernator with a capacity for substantial fattening, would continue to hibernate well beyond winter. I also quantified how long they were able to hibernate without access to food before their body fat stores were depleted. Pygmy-possums exhibited a prolonged hibernation season lasting on average for 310 days. The longest hibernation season in one individual lasted for 367 days. For much of this time, despite periodic arousals after torpor bouts of approximately 12.5 days, energy expenditure was reduced to only approximately 2.5% of that predicted for active individuals. These observations represent the first report on body-fat-fuelled hibernation of up to an entire year and provide new evidence that prolonged hibernation is not restricted to placental mammals living in the cold.

A NEW AUSTRALIAN SPECIES OF STOMATODEX FAIN (ACARI: DEMODECIDAE) FROM THE OESOPHAGUS OF CERCARTETUS NANUS (DESMAREST) (MARSUPIALIA)

Stomatodex cercarteti sp.n. is described from adults and immatures from the oesophageal lining of the eastern pygmy possum, Cercartetus nanus. This is the first record of this genus from Australia and from a marsupial host.

Aspects of the ecology of the eastern pygmy-possum Cercartetus nanus at Jervis Bay, New South Wales.

A variety of ecological data were collected on the eastern pygmy-possum Cercartetus nanus at Jervis Bay, in south-eastern New South Wales between March 2006 and January 2007. Elliott traps, pitfall traps, nest-boxes and spotlighting were used to survey for the species. Data on habitat suitability including abundance of food plants (flowering trees and shrubs) and potential nest sites were also collected. Home range data were gathered via radio telemetry. Three individuals were caught in 2150 trap-nights and one animal was re-trapped once. Radio-collars were attached to one animal of each sex and tracked for 11 days during March 2006. These possums used areas (using minimum convex polygons) of 0.85 ha (male) and 0.19 ha (female). The average overnight distance moved was 44 m for the male (range = 4-81 m) and 19 m for the female (range = 0-56 m). Nest-sites included hollows in the proteaceous shrubs Banksia serrata and B. ericifolia, and in the myrtaceous trees Corymbia gummifera, Eucalyptus sclerophylla, and Syncarpia glomulifera. Cercartetus nanus captures were confined to two sites that had the most prolific flowering of potential food plants and the highest availability of potential nest-sites. A review of literature and previous surveys of the surrounding area was a necessary precursor to field study and produced 57 records. Greater understanding of the impacts of development and fire are needed for conservation and management of this species.

The fossil distribution of the eastern pygmy-possum Cercartetus nanus.

A review of the literature on Cercartetus nanus at 12 fossil sites in NSW. The accumulating agents involved were owls and mammalian predators.

Some parasites of the eastern pygmy-possum, Cercartetus nanus (Marsupialia: Burramyidae).

This short review presents 25 parasite records (11 species) for Cercartetus nanus and summarises data on the fleas, mites, ticks, nematodes and a land planarian that have been recorded from this host.

Distribution, habitat and conservation status of the eastern pygmy-possum Cercartetus nanus in Tasmania.

We review literature pertaining to the distribution, habitat and conservation status of the eastern pygmy-possum Cercartetus nanus in Tasmania. Records from fauna surveys, museum specimens, and the Tasmanian Natural Values Atlas database, suggest that although C. nanus is widespread, it occurs in low numbers in Tasmania. From 51 fauna surveys examined, only 19 C. nanus were detected in a total of 47,087 Elliott trap-nights, 5,665 pitfall trap-nights, 196 scats or owl pellets, 899 spotlight hours, and 86 predator stomachs. A total of 102 Tasmanian C. nanus specimens was located in Australian and overseas museums. These records combined with 23 from the Natural Values Atlas database and 61 from an earlier published collation represent 99 of 679 grid squares (10 km x 10 km) overlaid across Tasmania (including King Island and Flinders Island). The patchy distribution of these records may be a reflection of low survey effort, low population numbers, low detectability or a combination of these and other factors. The highest number of records for a single locality was only four. Available data suggest that Tasmanian populations may be small and therefore potentially at risk from habitat loss, inappropriate fire regimes, and firewood collection. We believe there is a pressing need for further surveys to more clearly define the conservation status of C. nanus in Tasmania.

Floristic and structural components of habitat use by the eastern pygmy-possum (Cercartetus nanus) in burnt and unburnt habitats

The eastern pygmy-possum (Cercartetus nanus) occurs broadly but patchily in south-eastern Australia. It is a small, difficult-to-trap marsupial with poorly known resource and habitat preferences. This study investigated the structural and floristic habitat resources used and selected by C. nanus in Royal National Park (which was heavily burnt by bushfire in 1994) and Heathcote National Park (most of which had remained unburnt for over two decades at the time of study), in central-coastal New South Wales. Three different sampling methods were used – pitfall traps, Elliott traps and hair tubes – with pitfall trapping being by far the most effective method for detecting C. nanus. Live-trapping in different habitats revealed higher numbers of C. nanus in unburnt and burnt woodland, burnt heathland and burnt coastal complex than in unburnt coastal complex and burnt and unburnt rainforest. To identify the components of habitat contributing to this pattern, we first scored floristic and structural features of vegetation around trap stations and then quantified habitat components further by using spool- and radio-tracking. We found little evidence that C. nanus responded to any structural components of habitat, although arboreal activity was greater, not surprisingly, in wooded than in burnt heathland habitats. C. nanus was associated most strongly with the abundance of certain plants in the Proteaceae and Myrtaceae. In particular, the species prefers Banksia spp. (probably for food) and Eucalyptus and Xanthorrhoea spp. (probably for shelter).

The value of nest boxes in the research and management of Australian hollow-using arboreal marsupials

Nest boxes have been recognised as research and management tools for arboreal marsupials in Australia for over 20 years. We review the published literature with the aim of describing the scope of studies conducted in Australia thus far and providing guidance to future research. We recognise three types of application in research: (1) detection of species, (2) study of a species’ ecology, and (3) investigation of box designs preferred by different species. Several species of arboreal marsupial may be detected more readily in nest boxes than by conventional survey techniques, allowing description of key aspects of their ecology; e.g. feathertail glider (Acrobates pygmaeus), eastern pygmy possum (Cercartetus nanus) and brush-tailed phascogale (Phascogale tapoatafa). Identifying the most favoured nest-box design for any species has implications for detection and management uses of nest boxes. More research is needed but preliminary findings suggest that species prefer narrow entrance holes, while height of the nest box above 3 m may be inconsequential. We recognise three types of management application: (1) species introduction, (2) support of populations of endangered species, and (3) strategic placement such as to enhance habitat connectivity. Currently there have been few attempts to use nest boxes to manage arboreal marsupials but further research is needed to realise their potential as a management tool.

Habitat utilisation by small mammals in a coastal heathland exhibiting symptoms of Phytophthora cinnamomi infestation

Phytophthora cinnamomi is a soil-inhabiting ‘water mould’ that is pathogenic to many native plant species in Australia, and has been shown to alter plant species abundance and richness, as well as the structure of vegetation in sclerophyllous vegetation. This study investigated the effects of P. cinnamomi-induced vegetation disturbance and habitat degradation on microhabitat associations of small mammals in a coastal heathland in southern Australia. Seven small mammal species were trapped in a P. cinnamomi-infested heathland community over four years. Trap stations were classified into three disease classes (non-diseased, active disease and post-disease) and structural and floristic aspects of the vegetation were recorded at each station. The mean number of species captured was greatest in non-diseased areas and least in post-disease areas. The total capture frequency of small mammals was lower in post-disease areas except where they were covered by thick stands of tall tea-tree (Leptospermum sp.). Combined small mammal captures were associated with thick vegetation and floristic factors. Captures of Antechinus agilis, Rattus fuscipes, Rattus lutreolus and Sminthopsis leucopus were greatest in non-diseased vegetation and were less frequent in areas of diseased vegetation. A. agilis and R. fuscipes captures were correlated with a floristic factor associated with non-diseased vegetation, while R. lutreolus was associated with structural factors, preferring thick vegetation. The impact on Cercartetus nanus and Isoodon obesulus could not be assessed owing to low captures of these species. Modification of vegetation structure and floristics associated with P. cinnamomi infestation is having a significant impact on the habitat utilised by the small mammal communities in the area. This impact highlights the need to identify and protect those areas that remain free of P. cinnamomi infestation. Continued spread of the pathogen will reduce the area of suitable small-mammal habitat able to support the diverse communities of the eastern Otway Ranges, Victoria, Australia.

Fossil Occurrences of Cercartetus Nanus (Marsupialia: Burramyidae) in South Australia

SummaryThis study documents the known prehistoric distribution of the eastern pygmy-possum Cercartetus nanus in South Australia. This is based on 10 caves (Bat Cave, Cathedral Cave, Comaum Forest Cave, Haystall Cave, Henschke Fossil Cave, Kilsbys Hole, Robertson Cave, Sleeping Cave, Victoria Fossil Cave, and Wet Cave) and one rockshelter deposit (Narcurrer Shelter) all from the south-east of South Australia. Comparison of prehistoric and modern distribution records for C. nanus suggest a recent northward range contraction. The oldest fossil C. nanus are from Cathedral Cave where dates as old as 279,000 years have been established. The bone assemblages were reported to be the result of natural pitfall death-traps or from predatory species such as owls and mammalian carnivores depositing prey remains in caves.

Detection of the eastern pygmy-possum Cercartetus nanus (Marsupialia: Burramyidae) at Barren Grounds Nature Reserve, New South Wales.

THE eastern pygmy-possum (Cercartetus nanus) has an extensive distribution, from south-eastern Queensland to south-eastern South Australia, and also into Tasmania (Strahan 1995). Despite this it is rarely detected in fauna surveys (Bowen and Goldingay 2000). This rarity in detection suggested that the species may be characterised by small and isolated populations, and therefore vulnerable to extinction. Consequently, it became listed as a 'Vulnerable' species in New South Wales (NSW) in 2001. Unless resolved, the low rate of detection of C. nanus will continue to hinder the acquisition of basic ecological information that is needed to more clearly define its conservation status and that is fundamental to the development of a recovery plan. An extensive body of survey data for NSW involving C. nanus has been reviewed by Bowen and Goldingay (2000). Among a range of survey methods aimed at detecting this species, trapping within flowering banksias and checking installed nest-boxes had the highest rates of detection. Indeed, one study in northern NSW captured 98 individuals over a 3- year period from within nest-boxes (Bladon et al. 2002). All other studies detected fewer than 15 C. nanus. It is clear that further research is required to investigate the effectiveness of a range of detection methods.

Distribution, habitat and conservation status of the eastern pygmy-possum Cercartetus nanus in Victoria.

We review the distribution, habitat and conservation status of the eastern pygmy-possum (Cercartetus nanus) in Victoria. Data on the habitat occurrences and rates of detection were gleaned from 133 published and unpublished fauna surveys conducted from 1968 to 2003 in Gippsland; northern Victoria; the Melbourne area and south-western region. C. nanus was reported from a broad range of vegetation communities, which predominantly included a dense mid-storey of shrubs rich in nectar-producing species such as those from the families Proteaceae and Myrtaceae. Survey effort using a range of methods was immense across surveys: 305,676 Elliott/cage trap-nights, 49,582 pitfall trap-nights, 18,331 predator remains analysed, 4424 spotlight hours, and 7346 hair-sampling devices deployed, 1005 trees stagwatched, and 5878 checks of installed nest-boxes. The surveys produced 434 records of C. nanus, with Elliott/cage trapping, pitfall trapping and analysis of predator remains responsible for the vast majority of records (93%). These data and those from the Atlas of Victorian Wildlife indicate that although C. nanus has a widespread distribution in Victoria, it is rarely observed or trapped in fauna surveys. Only 11 (8%) of the surveys we reviewed detected &gt;10 individuals. C. nanus is likely to be sensitive to several recognised threatening processes in Victoria (e.g., feral predators, high frequency fire, feral honeybees). There is also evidence of range declines in several regions, which suggests that the species is vulnerable to extinction. Therefore, we recommend that it be nominated as a threatened species in Victoria.