Rendall, AR. Webb, V. Sutherland, DS. White, JG. Renwick, L. Cooke, R.
Understanding when and where roadkill is most likely to occur is vital to reducing wildlife-vehicle collisions. However, little is known about how roadkill rates change through time and whether or not the key influences on roadkill also change. Understanding changes in roadkill will facilitate the best implementation of mitigation measures. We aimed to determine how roadkill rates have changed between two distinct time periods and assess whether the spatial and temporal drivers of roadkill rates may have changed: with a view to informing species-specific mitigation strategies.
Managing ecosystems in the face of complex species interactions, and the associated uncertainty, presents a considerable ecological challenge. Altering those interactions via actions such as invasive species management or conservation translocations can result in unintended consequences, supporting the need to be able to make more informed decisions in the face of this uncertainty.
Rendall, AR., White, JG., Cooke, R., Whisson, DA., Schneider, T., Beilharz, L., Poelsma, E., Ryeland, J., Weston, MA.
Autonomously triggered cameras are a common wildlife survey technique. The use of attractants and surrounding microhabitats are likely to influence detection probabilities and survey outcomes, however, few studies consider these factors. We compared three attractants (peanut butter-based, tuna-based, and a control) in a Latin square design through a coastal shrubland with high microhabitat variability at Cape Otway, Victoria, Australia. Deployments involved 36 cameras for four days in each of five years. The percentage cover of each vegetation structural type (low [no or sparse cover], moderate [grass] or high [shrubs]) within 20 m of each camera was calculated and reduced to a single variable using PCA. Dynamic occupancy modelling, with lure type and vegetation structure as covariates of detection probability, found that peanut butter attracted the greatest diversity of species (24 of 35 species, 69%) and yielded the greatest number of detections (50% of 319) when compared to tuna oil (66% and 24% respectively) and the control (43% and 26% respectively). Peanut butter attracted more Macropodidae (wallabies) and Muridae (rats and mice); however, vegetation structural variables were the greatest influence on Corvidae/Artamidae (raven/currawong) detections with higher detectability in more open areas. Vegetation structure also influenced Muridae detections. This study reinforces the critical choice of appropriate attractants and camera placement when investigating vertebrate groups and highlights the role of microhabitat in the detection of small mammals and birds. We suggest future large-scale camera surveys consider different bait types and microhabitats in their designs, to control for any biases and enable future advice on ‘optimal’ methods.
Number of nights required to be 95% confidence of detecting Macropodidae species (top) and Muridae species (bottom) across three attractants: peanut butter (solid line), tuna oil (dashed line), and control (dot line). Red dash-dot line represents target 95% confidence in a site-specific absence.
Charuvi, A., Lees, D., Glover, HK., Rendall, AR., Dann, P. and Weston, MA.
For a given species, why does one bird fly when another doesn’t?
Image credit: Michael Weston
This process is often referred to as habituation – where some individuals become accustomed to repeated stimuli and therefore respond less. Habituation has been extensively discussed in relation to its importance in informing guidelines for mitigating the impacts of human disturbance on wildlife. However, most studies only consider behavioural responses of individuals, not the underlying physiological responses (Weston et al. 2012). Only a limited number of studies have considered the behavioural and physiological response of individuals to threatening stimuli. These studies are important as it may be that birds respond physiologically prior to showing any behavioural response, meaning our measures of the impact of negative stimuli (i.e. human usage of an ecosystem) may under-estimate true impacts. Therefore, in this study we investigated whether physiological costs were incurred prior to, or simultaneously with a behavioural response.
We investigated the spatial and temporal activity of long-nosed potoroos (Potorous tridactylus tridactylus) and feral cats (Felis catus) on French Island, Victoria. This population of potoroo’s has co-existed with cats since their introduction to the island, and we sought to understand the mechanisms by which this population was able to continue to persist.
Zonation is a dominant feature of coastal ecologies, yet comparatively few studies are available on zonation of ecological assemblages in coastal dunes. No study is available which examines zonation of small terrestrial mammals in dunes. We use a dataset of 10 years of mammal trapping near Cape Conran, eastern Victoria, Australia and show that small mammals were common in this dune system. The only introduced small mammal was detected in a narrow band above the beach/dune interface, while native small mammal assemblages dominated in the rest of the dune field. This clear zonation may result from habitat preference, competition, predation and species-specific predator risk tolerances, marine or beach subsidies or a combination of these influences.
