Rhiana D Meade

Bio: Rhiana D Meade is an academic researcher. The author has contributed to research in topics: Tree-kangaroo & Dendrolagus lumholtzi. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.

Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats.

Abstract: arboreal folivores, such as Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in Far North Queensland, Australia, scat counts seem to be the most promising ecological technique. However, the occurrence of Lumholtz’s Tree-kangaroos in seasonal rainforests with dense understory, a high diversity of coprophagous invertebrates and with sympatric folivores increases the probability of invalidating results based on scat surveys. This study investigates scat production and scat decomposition patterns to select diagnostic traits of Lumholtz’s Tree-kangaroo scats that can, under varying environmental conditions, assist in distinguishing between fresh and old scats to reduce false positive and false negative errors in species presence due to non- or/and misidentification of scats. Scat production rates of six captive Lumholtz’s Tree-kangaroos were highly variable resulting in different scat numbers and masses. Changes in scat size (mass and circumference), pH and the appearance of mould were monitored under different laboratory conditions and in forest trials. Under wet conditions scats gained mass until they reached an apparent plateau of 130% of their original mass. Scats under dry conditions lost up to 90% of their original mass. Changes in mass were accompanied by changes in circumference of scats. By Day 3 scats had developed signs of mould under laboratory conditions and showed an acidic pH. Field trials revealed a high loss of scats due primarily to their consumption by dung beetles (Scarabaeoidea). For studying Lumholtz’s Tree-kangaroos in their rainforest environment, scat surveys should be confined to dry periods to reduce the probability of false negative errors due to activity of coprophagous invertebrates. Additionally, only fresh scats of average size and with an acidic pH should be used to minimize the risk of misidentifying small sized scats from Red-legged Pademelons (Thylogale stigmatica) as tree-kangaroo scats. More studies on species-specific diagnostic traits of Lumholtz’s Tree-kangaroo scats are necessary to validate false negative and false positive errors in scat counts for this species.

Bearded pig (Sus barbatus) utilisation of a fragmented forest-oil palm landscape in Sabah, Malaysian Borneo

Abstract: Context: Oil palm plantations have become a dominant landscape in Southeast Asia, yet we still understand relatively little about the ways wildlife are adapting to fragmented mosaics of forest and oil palm. The bearded pig is of great ecological, social, and conservation importance in Borneo and is declining rapidly due to habitat loss and overhunting. Aims: We sought to assess how the bearded pig is adapting to oil palm expansion by investigating habitat utilisation, activity patterns, body condition, and minimum group size in a mosaic composed of forest fragments and surrounding oil palm. Methods: We conducted our study in Sabah, Malaysian Borneo, in and around the Lower Kinabatangan Wildlife Sanctuary, an area consisting of secondary forest fragments (ranging 1200-7400 ha) situated within an extensive oil palm matrix. We modelled bearded pig habitat use in forest fragments and oil palm plantations using survey data from line transects. Camera traps placed throughout the forest fragments were used to assess pig activity patterns, body condition, and minimum group size. Key results: All forest transects and 80% of plantation transects showed pig presence, but mean pig signs per transect were much more prevalent in forest (70.00 ± 13.00 SE) than in plantations (0.91 ± 0.42 SE). Pig tracks had a positive relationship with leaf cover and a negative relationship with grass cover; pig rooting sites had a positive relationship with wet and moderate soils as compared to drier soils. Pigs displayed very good body condition in forests across the study area, aggregated in small groups (mean = 2.7 ± 0.1 SE individuals), and showed diurnal activity patterns that were accentuated for groups with piglets and juveniles. Conclusions: Our findings suggest that bearded pigs in our study area regularly utilise oil palm as habitat, given their signs in most oil palm sites surveyed. However, secondary forest fragments adjacent to oil palm remain the most important habitat for the bearded pig, as well as many other species, and therefore must be conserved. Implications: Consistent bearded pig presence in oil palm is a potential indication of successful adaptation to agricultural expansion in the study area. However, the net effect of oil palm expansion in the region on bearded pig populations remains unknown.

Estimating the abundance of the bilby (Macrotis lagotis): a vulnerable, uncommon, nocturnal marsupial

Abstract: The bilby (Macrotis lagotis) is listed as Vulnerable in Australia, is strictly nocturnal and shy, and it has proven difficult to estimate its population abundance. The aim of this study was to determine methodology that would reliably estimate the abundance of the bilby within an enclosure at Currawinya National Park, south-west Queensland. We estimated the abundance of bilbies on long-term monitoring plots by counting pellets comparing two methods: counting standing odorous pellets using distance sampling and counting newly deposited pellets (FAR). Pellet deposition rate and decay rate were also estimated to enable population estimation using distance sampling. The density of odorous (<14 days old) standing pellets and old pellets was highest in October 2011 and dropped dramatically when plots were revisited in March 2012 and July 2012. Counting standing pellets using distance sampling provided a rigorous estimate of abundance of bilbies at Currawinya. Bilby density and pellet deposition rates were too low for the FAR method to accurately or precisely estimate bilby density. A population crash within the enclosure following an invasion of feral cats was mirrored by a dramatic decrease in pellet density. Incorporating detectability into abundance estimation should be carefully considered for conservation purposes.

Studying food preferences in captive cryptic folivores can assist in conservation planning: the case of the Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi)

Abstract: Food preferences of the arboreal Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi), endemic to the tropical rainforests of north-eastern Australia, are largely unknown, but are likely to affect the movements of this mammal within its home range and across a fragmented landscape. Food selection was investigated by applying a consumption ranking system to 35 browse species provided to six captive animals throughout different years. Animals consumed foliage from a wide range of rainforest tree species, but at different intensities, suggesting that Lumholtz’s tree-kangaroo is a selective folivore. All studied animals showed a general preference for the foliage of the northern olive (Chionanthus ramiflorus) and the umbrella tree (Schefflera actinophylla) throughout the year while foliage from acacias (Acacia spp.), milky pine (Alstonia scholaris) and pink ash (Alphitonia petriei) was less frequently consumed. Foliage from figs (Ficus spp.) and the northern tamarind (Diploglottis diphyllostegia) was consumed at higher rates only at certain times of the year, suggesting the existence of seasonal preferences. The knowledge of general and seasonal food preferences of this large arboreal mammal may allow a better prediction of animal movements and therefore can assist in conservation efforts. Recommendations for the integration of these findings in restoration projects are given.

Cost-effectiveness of thermal imaging for monitoring a cryptic arboreal mammal

Abstract: Context The development of reliable and cost-efficient survey techniques is key to the monitoring of all wildlife. One group of species that presents particular challenges for monitoring is the arboreal mammals. Traditional techniques for detecting these species often yield low detection probabilities (detectability) and are time-consuming, suggesting the potential for novel methods to enhance our understanding of their distribution, abundance and population trajectories. One technique that has been shown to increase detectability in a range of terrestrial species is thermal imaging, although it has rarely been applied to arboreal species. The true conservation status of Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) is uncertain because of low detectability under typical survey techniques, and a more suitable method is required to enable effective monitoring of the species, making it an ideal candidate for the present study. Aims We aimed to compare the success and cost-effectiveness of surveys utilising thermal imaging with two traditional methods, namely, spotlighting and daytime surveys, so as to optimise monitoring of D. lumholtzi. Methods We conducted surveys at 10 sites in Queensland (Australia) where D. lumholtzi was known to occur, by using each method, and modelled both the detectability of D. lumholtzi and the cost-effectiveness of each technique. Key results Detectability of D. lumholtzi was significantly higher with the use of thermal imaging than it was with the other survey methods, and thermal detection is more cost-effective. In average survey conditions with a trained observer, the single-visit estimated detectability of D. lumholtzi was 0.28 [0.04, 0.79] in a transect through rainforest, by using thermal imaging. Using only spotlights, the detection probability was 0.03 [0, 0.28] under the same conditions. Conclusions These results show that incorporating thermal technology into monitoring surveys will greatly increase detection probability for D. lumholtzi, a cryptic arboreal mammal. Implications Our study highlighted the potential utility of thermal detection in monitoring difficult-to-detect species in complex habitats, including species that exist mainly in dense forest canopy.

Estimating macropod grazing density and defining activity patterns using camera-trap image analysis

Abstract: Context When measuring grazing impacts of vertebrates, the density of animals and time spent foraging are important. Traditionally, dung pellet counts are used to index macropod grazing density, and a direct relationship between herbivore density and foraging impact is assumed. However, rarely are pellet deposition rates measured or compared with camera-trap indices. Aims The aims were to pilot an efficient and reliable camera-trapping method for monitoring macropod grazing density and activity patterns, and to contrast pellet counts with macropod counts from camera trapping, for estimating macropod grazing density. Methods Camera traps were deployed on stratified plots in a fenced enclosure containing a captive macropod population and the experiment was repeated in the same season in the following year after population reduction. Camera-based macropod counts were compared with pellet counts and pellet deposition rates were estimated using both datasets. Macropod frequency was estimated, activity patterns developed, and the variability between resting and grazing plots and the two estimates of macropod density was investigated. Key Results Camera-trap grazing density indices initially correlated well with pellet count indices (r2 = 0.86), but were less reliable between years. Site stratification enabled a significant relationship to be identified between camera-trap counts and pellet counts in grazing plots. Camera-trap indices were consistent for estimating grazing density in both surveys but were not useful for estimating absolute abundance in this study. Conclusions Camera trapping was efficient and reliable for estimating macropod activity patterns. Although significant, the relationship between pellet count indices and macropod grazing density based on camera-trapping indices was not strong; this was due to variability in macropod pellet deposition rates over different years. Time-lapse camera imagery has potential for simultaneously assessing herbivore foraging activity budgets with grazing densities and vegetation change. Further work is required to refine the use of camera-trapping indices for estimation of absolute abundance. Implications Time-lapse camera trapping and site-stratified sampling allow concurrent assessment of grazing density and grazing behaviour at plot and landscape scale.