Diet analysis of mammals, raptors and reptiles in a complex predator assemblage in the Blue Mountains, eastern Australia

Pascoe, Jack H.; Mulley, R. C.; Spencer, Ricky‐John; Chapple, Rosalie S.

doi:10.1071/zo11082

Cited by 23 publications

(17 citation statements)

References 25 publications

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“…These bottom-up factors likely affect dingoes similarly [20,68]. Mesopredators (especially scavenging foxes and goannas) may also derive substantial benefit from dingoes through kleptoparisitism [19,69], which may also have contributed to our observations. The relative strength of top-down and bottom-up processes affecting predator populations in Australia has not been well studied, though it seems clear from our results that mesopredator populations in the rangelands do not appear to be enhanced by contemporary dingo/fox control practices.…”

Section: Discussionmentioning

confidence: 99%

Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments

Allen

Allen²,

Engeman³

et al. 2013

Front Zool

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IntroductionTerrestrial top-predators are expected to regulate and stabilise food webs through their consumptive and non-consumptive effects on sympatric mesopredators and prey. The lethal control of top-predators has therefore been predicted to inhibit top-predator function, generate the release of mesopredators and indirectly harm native fauna through trophic cascade effects. Understanding the outcomes of lethal control on interactions within terrestrial predator guilds is important for zoologists, conservation biologists and wildlife managers. However, few studies have the capacity to test these predictions experimentally, and no such studies have previously been conducted on the eclectic suite of native and exotic, mammalian and reptilian taxa we simultaneously assess. We conducted a series of landscape-scale, multi-year, manipulative experiments at nine sites spanning five ecosystem types across the Australian continental rangelands to investigate the responses of mesopredators (red foxes, feral cats and goannas) to contemporary poison-baiting programs intended to control top-predators (dingoes) for livestock protection.ResultShort-term behavioural releases of mesopredators were not apparent, and in almost all cases, the three mesopredators we assessed were in similar or greater abundance in unbaited areas relative to baited areas, with mesopredator abundance trends typically either uncorrelated or positively correlated with top-predator abundance trends over time. The exotic mammals and native reptile we assessed responded similarly (poorly) to top-predator population manipulation. This is because poison baits were taken by multiple target and non-target predators and top-predator populations quickly recovered to pre-control levels, thus reducing the overall impact of baiting on top-predators and averting a trophic cascade.ConclusionsThese results are in accord with other predator manipulation experiments conducted worldwide, and suggest that Australian populations of native prey fauna at lower trophic levels are unlikely to be negatively affected by contemporary dingo control practices through the release of mesopredators. We conclude that contemporary lethal control practices used on some top-predator populations do not produce the conditions required to generate positive responses from mesopredators. Functional relationships between sympatric terrestrial predators may not be altered by exposure to spatially and temporally sporadic application of non-selective lethal control.

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Section: Discussionmentioning

confidence: 99%

Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments

Allen

Allen²,

Engeman³

et al. 2013

Front Zool

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“…Reptile scavengers (especially varanids; Fig. 2d) may also be affected, because they consume large amounts of carrion (Pascoe et al 2011). To our knowledge, few studies have investigated or demonstrated Pb exposure from ammunition in wild reptiles, whereas the study of Camus et al (1998) demonstrated Pb poisoning in farmed American alligators (Alligator mississippiensis) fed carcasses shot with Pb-based bullets.…”

Section: Australian Wildlifementioning

confidence: 99%

Heads in the sand: public health and ecological risks of lead-based bullets for wildlife shooting in Australia

et al. 2018

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Lead (Pb) is a toxic element banned from fuel, paint and many other products in most developed countries. Nonetheless, it is still widely used in ammunition, including rifle bullets, and Pb-based bullets are almost universally used in Australia. For decades, poisoning from Pb shot (shotguns) has been recognised as a cause of disease in waterfowl and Pb shot has been subsequently banned for waterfowl hunting in many jurisdictions. However, the risks posed by Pb-based bullets (rifles) have not been similarly recognised in Australia. Pb-based rifle bullets frequently fragment, contaminating the tissue of shot animals. Consuming this Pb-contaminated tissue risks harmful Pb exposure and, thus, the health of wildlife scavengers (carrion eaters) and humans and their companion animals who consume harvested meat (game eaters). In Europe, North America and elsewhere, the environmental and human health risks of Pb-based bullets are widely recognised, and non-toxic alternatives (e.g. copper-based bullets) are increasingly being used. However, Australia has no comparable research despite widespread use of shooting, common scavenging by potentially susceptible wildlife species, and people regularly consuming shot meat. We conclude that Australia has its collective 'head in the sand' on this pressing worldwide One Health issue. We present the need for urgent research into this field in Australia.

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“…Significant diet overlap can also occur among sympatric predators from different taxonomic classes, especially between generalist species that forage opportunistically (Pascoe et al ). In the Pacific Northwest, native mammalian carnivores, such as the fisher ( Martes pennanti ) and American marten ( M. americana ), may experience exploitative competition with barred owls because these species are also largely nocturnal, share habitats, and exploit strikingly similar prey species including voles, deer mice ( Peromyscus maniculatus ), shrews, and lagomorphs (Buskirk and MacDonald , Zielinski and Duncan ; Fig.…”

Section: Pontential Effects On the Predator Communitymentioning

confidence: 99%

Potential trophic cascades triggered by the barred owl range expansion

et al. 2016

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Recently, the barred owl (Strix varia) has expanded its range into the Pacific Northwest of the United States resulting in pronounced effects on the demography and behavior of the northern spotted owl (S. occidentalis caurina). The range expansion has brought together historically allopatric species, creating the potential for significant changes in the avian predator community with possible cascading effects on food-web dynamics. The adverse effects of the barred owl on the behavior and demography of the northern spotted owl are well-documented, but little is known about the immediate and long-term effects changes in the predator community may have on native species composition and ecosystem processes. Based on northern spotted owl and barred owl selection for diet and habitat resources, there is a potential for trophic cascades within the region's predator and prey communities, differing responses by their shared and unique prey species, and possible direct and indirect effects on ecosystem processes. We explored the possible ecological consequences of the barred owl range expansion to wildlife communities of the Pacific Northwest based on the theoretical underpinnings of predator-prey relationships, interspecific competition, intraguild predation, and potential cascading trophic interactions. Negative effects on fitness of northern spotted owls because of interspecific competition with barred owls are strong selection forces that may contribute to the regional extinction of the northern spotted owl. In addition, we posit that shared prey species and those uniquely consumed by barred owls, along with other competing native predators, may experience changes in behavior, abundance, and distribution as a result of increased rates of predation by rapidly expanding populations of barred owls.

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Diet analysis of mammals, raptors and reptiles in a complex predator assemblage in the Blue Mountains, eastern Australia

Cited by 23 publications

References 25 publications

Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments

Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments

Heads in the sand: public health and ecological risks of lead-based bullets for wildlife shooting in Australia

Potential trophic cascades triggered by the barred owl range expansion

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