Jonathan Parkyn

Population stability in the endangered Fleay’s barred frog (Mixophyes fleayi) and a program for long-term monitoring

Abstract. In the wake of the global decline in amphibians there is a need for long-term population monitoring. Previous research suggested that the endangered Fleay’s barred frog (Mixophyes fleayi) had recovered after a severe decline. We aimed to determine whether this recovery has been sustained and to test an example of a monitoring program that could be employed at intervals of five or more years to assess long-term population stability. We conducted capture–mark–recapture five years after the last detailed census at Brindle Creek in Border Ranges National Park, New South Wales. Frogs were captured along a 200 m creek transect between September 2013 and February 2014. We used program Mark to estimate demographic parameters of adult male frogs using two modelling approaches: robust design (RD) and the POPAN formulation of the Jolly–Seber model. Abundance was estimated at 38.2 ± 0.5 (s.e.) (RD) and 46.0 ± 2.7 (POPAN). Abundance in 2008 was estimated at 53.2 ± 10.0 (POPAN) male frogs. Estimates of apparent monthly survival over our five-month-long study were very high (RD: 1.0 ± 0.0; POPAN: 1.0 ± 0.02). Recapture estimates were also high (RD: 0.40 ± 0.07 to 0.72 ± 0.05 per session; POPAN: 0.84 ± 0.05 per month). These data suggest that the Brindle Creek population has remained relatively stable over a period of ∼10 years.

Initial observations of a population of Mitchell's Rainforest Snail Thersites mitchellae Cox 1864

Mitchells Rainforest Snail Thersites mitchellae Cox 1864 is listed as ‘endangered’ under the NSW Threatened Species Conservation Act 1995, as ‘critically endangered’ under the Environment Protecti...

Australian land snails: a review of ecological research and conservation approaches

Land snails are an important yet often neglected component of Australias biological diversity. Despite high levels of diversity within this group and the identification of many narrow range endemic species as being of conservation concern, there have been few detailed studies that document the ecology and conservation requirements of the group. A range of threats has been suggested, yet relatively few have been rigorously assessed. Whilst factors such as land clearing are readily apparent and have resulted in extinctions, other threats such as climate change are not well understood. This paper reviews studies conducted on terrestrial molluscs in Australia and highlights the need for further targeted ecological research, given the likely level of on-going threats. We urge researchers to apply rigorous approaches to data collection that will enable a deeper understanding of the factors governing distribution and abundance. Approaches used in other areas of conservation biology offer considerable scope for application to land snails and for the development of appropriate conservation strategies.

Movement of small mammals through a road-underpass is facilitated by a wildlife railing

Wildlife underpasses in Australia are commonly fitted with timber railings to facilitate the passage of arboreal and scansorial mammals but there are no published accounts of railing use. We compared detections of such mammals on railings in two underpasses to detections on the ground in these and other underpasses. The brown antechinus (Antechinus stuartii) and the black rat (Rattus rattus) were detected on a closely monitored railing on 12–14% of nights over three years. These species were detected on the ground of underpasses on <1% of nights. Koalas (Phascolarctos cinereus) and brushtail possums (Trichosurus spp.) were infrequently detected, koalas only on the ground and brushtail possums mostly on the ground. These observations suggest that road crossings by small scansorial mammals can be facilitated by timber railings.

Population monitoring of a threatened gliding mammal in subtropical Australia

Abstract. Population monitoring is fundamental to the conservation of threatened species. This study aimed to develop an effective approach for long-term monitoring of the yellow-bellied glider (Petaurus australis) in north-east New South Wales. We conducted repeat surveys to account for imperfect detection and used counts in abundance modelling to produce indices of abundance. We used simulations to explore refinements to our study design. Surveys over three consecutive years produced 195 detections with >95% of detections by call. The probability of detection varied across years and survey occasions, ranging from 0.22 to 0.71. Abundance estimates were remarkably constant across years, ranging from 2.3 ± 0.5 to 2.4 ± 0.6 individuals per site. Occupancy estimates were also constant across years (0.90–0.91). Simulations were run to investigate the influence of the number of surveys (2 or 3) and the number of survey sites (20, 40 or 50) on the probability of occupancy. The design that reduced bias and provided an adequate improvement to precision was that of three visits to 40 survey sites. This design should be adequate to detect a decline in population abundance. Further studies of this kind are needed to better understand the population dynamics of this species.

Habitat use and movement patterns of the endangered land snail Thersites mitchellae (Cox, 1864) (Camaenidae)

ABSTRACT Thersites mitchellae (Cox, 1864) (Camaenidae) is a regionally endemic Australian land snail that is critically endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). We studied its habitat use and movement patterns. Knowledge of habitat use is relevant to the conservation of the species, and knowledge of movements is relevant to the interpretation of the results of capture-recapture studies and occupancy-based habitat models. We provide quantitative data of nightly distances travelled, the probability of moving on a night, retreat site selection, overnight substrate use and activity. A total of 636 location positions for 11 snails was recorded on 12 nights over an 18-day period. Nocturnal movements measured at approximately 2-hour intervals showed that the mean nightly movement was 457.8 cm. The maximum nightly movement by an individual was 1,575 cm, and the maximum nightly displacement was 1,270 cm. Over the study period, the maximum movement from capture was 74.45 m, and the maximum displacement was 31.80 m. The results show that the probability of moving on a night, and the nightly distance moved once active both increase with increasing humidity up to a maximum and then decline. Whilst individuals did not return to the same retreat site location with any reliability, there is evidence of active and frequent selection of particular retreat site types within selected habitats. Snails most frequently selected sedge retreat in rainforest (66.7%) and in paperbark wetland (59.3%), and despite the scarcity of sedge in palm forest, it was the most frequented retreat site group overall (42.5%). Snails selected palm frond retreats most frequently in the palm forest (66.7%), and coarse woody debris (CWD) was selected in all habitats (17.9%) and most frequently in the palm forest (27.8%). Statistical analysis revealed significant variation among individuals in their relative use of retreat site types, and significant association between the selection of retreat site types and the initial habitat in which the individuals were located.

Use of tall wooden poles by four species of gliding mammal provides further proof of concept for habitat restoration

Tall wooden poles (glide poles) and rope canopy-bridges are frequently installed along new highways in Australia to maintain population connectivity for gliding mammals. Knowledge of the use of these structures is rudimentary. We monitored two pairs of glide poles and a canopy-bridge over three years at Port Macquarie, New South Wales. The sugar glider (Petaurus breviceps) and the squirrel glider (Petaurus norfolcensis) were collectively detected on 12–18% of nights on the pole pairs compared with 1% on the rope-bridge. The feathertail glider (Acrobates frontalis) was detected on 3% of nights on the pole pairs compared with 0.2% on the rope-bridge. The yellow-bellied glider (Petaurus australis) was detected twice on one pole. Our results demonstrate that gliding mammals readily use glide poles. Further research is needed to resolve whether glide poles can mitigate the barrier effect of the road canopy gap.

No evidence of protracted population decline across 17 years in an unmanaged population of the green and golden bell frog in north-eastern New South Wales

Abstract. Describing the population trends of threatened species over time is central to their management and conservation. The green and golden bell frog (Litoria aurea) is a formerly common species of south-eastern Australia that has declined to ∼40 populations in New South Wales, and experienced a substantial contraction of its geographic range. We aimed to determine whether an unmanaged population at the northern end of its range had declined across a 17-year period. We estimated population size at the beginning and end of this period, using several population models to fully characterise this population. Different modelling approaches gave different population estimates. Based on a similar number of survey occasions the adult male segment of the population was estimated using the Popan model at 112.0 (±13.5, s.e.; 95% CI: 85.5–138.8) in 1998/99 and 95.2 (±17.6; 60.8–129.7) in 2015/16. With the inclusion of maturing subadults following the practice of earlier studies, the population was estimated at 163.6 (±25.9; 112.8–214.5) males in 2015/16. These estimates represent an index of a larger population because the largest wetland was subsampled. Our data provide no evidence of a declining population. Our study highlights the need to understand the implications of using different population models and two age-classes to estimate population parameters.

The natural diet of the endangered camaenid land snail Thersites mitchellae (Cox, 1864) in northern New South Wales, Australia

The natural diet of the camaenid land snail Thersites mitchellae (Cox, 1864) was investigated by examination of the faecal contents of specimens collected from a range of substrates. The composition of faecal pellets from 22 snails obtained from three different substrates was determined. The results demonstrate that T. mitchellae has a generalist feeding strategy that varies with substrate. Fungal material contributed a high proportion of the diet, suggesting that coarse woody debris (a common fungal substrate) may be an important requirement for populations of T. mitchellae in rainforestassociated habitats. Thersites mitchellae was the first species for which a critical habitat determination was made under the New South Wales Threatened Species Conservation Act 1995. This study adds to our knowledge of the biology of this poorly known land snail. Future studies would benefit from obtaining data pertaining to the timing and frequency of fungal dispersal and substrate preferences to gain further understanding about the availability of fungi as a food source.