Context Predators are major beneficiaries of artificial water points in arid environments, yet little is known of the effects of water on the distribution of many sympatric species. Intraguild interactions around water points in arid Australia may play a significant role in structuring mammalian predator assemblages and influence spatial predation on some native prey species. Aims We examined how management of an apex predator, the dingo (Canis lupus dingo), influenced the distribution of two introduced mesopredators, foxes (Vulpes vulpes) and feral cats (Felis catus), around water points in arid Australia. Methods The spatial activity of dingoes, foxes and feral cats was assessed at five study sites with varying dingo management regimes. Sampling of predator activity was monitored using track counts at measured proximity to water points. Key results At sites where dingoes were uncontrolled, foxes were less likely to be found within 5 km of water points; conversely, where dingoes were controlled using exclusion fencing, fox activity was highest near water. Where dingo activity was reduced using 1080 baiting, feral cats were found closer to water. Conclusions These patterns suggest that the presence of dingoes instigates avoidance behaviour by foxes and feral cats, and through doing so may limit the use of artificial waters by these mesopredators. Through limiting access to such an essential resource in arid environments, dingoes may reduce mesopredator populations and minimise their impact on native prey. Implications For the conservation of native biodiversity, it may prove beneficial to maintain intact dingo populations due to their suppressive effect on mesopredators.
The detectability of nocturnal carnivores is very low, because such data on many species can be difficult to acquire. Here, we design an automatic thermal video recording system for studying cryptic mammalian predators at food and water resources in Australia. We trialed different sampling procedures in contrasting environments between August 2005 and February 2006 to identify aspects of survey design that influenced video interpretability. We then compared the accuracy of the remote recording system to that of direct human observation. We found our system to be most effective when temperature settings were correctly adjusted and procedures were adapted for the sampling environment. We identified that the presence of vegetation and the distance between the target species and camera were the most important factors in video interpretability. The remote recording system was found to be as effective at recording both visits and behavior as direct human observation at a focal point. We propose that the automatic thermal video capture system has the potential to be an extremely useful tool for monitoring otherwise difficult to observe species. Ó
The intentional movement of species outside their indigenous rangeassisted colonisationis an emerging tool in conservation. Here, we outline the process developed to identify and assess candidate sites for assisted colonisation of the critically endangered Northern Corroboree Frog (Pseudophryne pengilleyi), a range-restricted species highly threatened by chytrid fungus. We first investigated the mechanisms associated with the persistence of Northern Corroboree Frog populations with chytrid fungus and then used a combination of desktop and field surveys to identify and assess sites based on habitat suitability, capacity to allow coexistence with chytrid fungus and hydrological properties. Candidate sites were further assessed by comparing environmental and climatic conditions to historical and persisting sites. Together, these methods allowed us to identify a site that appears to be highly suitable for the species. The process outlined here provides a template for assessing assisted colonisation sites for species where ongoing threats rule out recipient sites within their indigenous range.
The removal of apex carnivores from ecosystems can impact the abundance and diversity of species in lower trophic levels. In arid ecosystems, where “bottom up” forces of primary productivity and resource availability strongly affect trophic interactions, the role of “top down” effects is still much debated. This study explored the potential role of an apex predator, the dingo, as a “top down” trophic regulator in Australian arid ecosystems under different levels of primary productivity and dingo management regimes. Consistent with the theory of top down regulation, strong relationships were found between dingo management, dingo activity and fox activity. Dingoes appeared to suppress fox activity where dingoes were uncontrolled or only opportunistically controlled. At sites where dingoes were absent or in low numbers, fox activity was higher, and this inverse relationship persisted regardless of rainfall. The activity of rabbits and small mammals was lower where dingoes were absent and fox activity was high, while the activity of macropods was higher in the absence of dingoes. Feral cat activity did not differ significantly between sites under different dingo management or between years. These results suggest that management of dingoes is a key determinant of fox activity and the activity of some prey under varying levels of productivity. Evidence from this research showed that while the strength of trophic regulation by dingoes may fluctuate, top down effects occurred both prior to and post significant rainfall events. Following this, top down regulation of fox populations during dry periods at sites where dingoes are retained may enable higher and more stable “baseline” densities of small vertebrates, from which a larger and more rapid rate of increase of these prey during the “boom” periods can occur. Understanding the relative strength and interactions of top down and bottom up forces in regulating populations, and under what ecological states the importance of each changes, is important for the long-term conservation of biodiversity in arid regions.
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