Continental‐scale analysis of feral cat diet in Australia, prey‐switching and the risk: benefit of rabbit control

Mutze, G. (2016). Continental‐scale analysis of feral cat diet in Australia, prey‐switching and the risk: benefit of rabbit control. Journal of Biogeography.

Recent analyses of geographical variation in cats’ diet across Australia have been used to highlight rabbit control as a conservation risk, on the basis that prey-switching by cats following rabbit control is likely to threaten Australian fauna. There is no direct evidence to support that proposition. However, there is direct evidence of repeated prey-switching due to seasonal fluctuations in uncontrolled rabbit populations, of long-term suppression of rabbit numbers by effective rabbit control, and that reduced rabbit abundance leads to reduced cat abundance, reduced predation of native fauna and recovery of threatened prey populations. Furthermore, rabbits are a known threat to many Australian native plants and rabbit control has proven benefits for their recovery, thereby offering long-term benefits for dependent fauna and broader ecosystem function. On the balance of evidence, rabbit control should be encouraged in Australia wherever possible, as a national conservation priority.

Feeding habits of house and feral cats on small Adriatic islands

Lanszki J., Kletečki E., Trócsányi B., Mužinić J., Széles G.L. & Purger J.J. 2015  (in press) Feeding habits of house and feral cats (Felis catus) on small Adriatic islands (Croatia). North-Western Journal of Zoology (online first): art.151708

The domestic cat (Felis catus), a globally recognised invasive predator, was introduced to the Adriatic islands (Croatia), but its feeding ecology and impacts on biodiversity in this region is unknown. We studied the feeding habits of house cats living in villages and feral cats on the outskirts of villages on two small islands (Olib and Silba) by analysing faecal samples collected in the spring and autumn periods. Our hypothesis was that the feeding strategies of cats as top mammalian predators vary in different environments, due to significant dissimilarities in their food resources. We surveyed the abundance of cats and their primary food types, e.g. small mammals, birds, rabbits Oryctolagus cuniculus, and lizards. Our results suggest that house cats fed most often on birds and household food, while feral cats ate mostly small mammals and lizards. Feral cats preferred the invasive mesopredator black rat (Rattus rattus) (Ivlev’s index of preference, feral cats Ei = 0.72, house cats Ei = 0.14), suggesting that cats might have an effect on rat populations. Common rabbits had a low density and were preyed on only occasionally. In both cat groups, predation on birds was more frequent during autumn migration when bird abundance was higher, than in the spring breeding period. Both groups were food generalists but in different ways, which is a fact that should be considered in planning predator pest control on the islands.

Optimal multispecies eradication schedules for a commonly encountered invaded island ecosystem

Bode, M., Baker, C. M., & Plein, M. (2015). Eradicating down the food chain: optimal multispecies eradication schedules for a commonly encountered invaded island ecosystem. Journal of Applied Ecology, 52(3), 571-579.

Islands are global hotspots of both biodiversity and extinction. Invasive species are a primary threat, and the majority of islands have been invaded by more than one. Multispecies eradications are essential for conserving the biodiversity of these islands, but experience has shown that eradicating species at the wrong time can be disastrous for endemic species.
Managers not only have to decide how to eradicate each invasive species, they need to determine when to target each species, and how to control multiple species with a limited budget. We use dynamic control theory to show that, when resources are limited, species should be eradicated in a particular order (an eradication schedule). We focus on a common invaded island ecosystem motif, where one invasive predator consumes two prey species (one endemic, one invasive), and managers wish to eradicate both invasives while ensuring the persistence of the endemic species. We identify the optimal eradication schedule for this entire class of problem. To illustrate the application of our solution, we also analyse a particular case study from California's Channel Islands.
For any island ecosystem that shares this motif, managers should begin by allocating all of their resources towards invasive predator control. Only later should resources be shifted towards controlling the invasive prey. This shift should ideally be gradual, but an abrupt shift is very close to optimal. The Channel Islands case study confirms these findings. Targeting both species simultaneously is substantially suboptimal.
We reach the robust conclusion that the same eradication schedule should be applied to any island with this ecosystem motif, even if the ecosystem contains different species to the Channel Islands case study.
Synthesis and applications. Although very numerous, the world's invaded island ecosystems could be described by a limited range of invaded ecosystem motifs. By calculating robust optimal eradication schedules for each motif, the approach defined in this study could offer rapid decision-support for a large number of future conservation projects where specific data are scarce.

Rats, cats and seabirds: hyperpredation and mesopredator release

Ringler, D., Russell, J., & Le Corre, M. (2015). Trophic roles of black rats and seabird impacts on tropical islands: Mesopredator release or hyperpredation?.Biological Conservation.

Rats contribute to the decline of tropical seabird populations by affecting their breeding success through direct predation of eggs and chicks. When they coexist with other predators, invasive rats may also generate indirect interactions via the changes they impose on the structure of communities and trophic interactions following invasion (‘hyperpredation process’), or when apex predators are eradicated from the ecosystem (‘mesopredator release effect’). Understanding these effects is necessary to implement restoration operations that actually benefit threatened seabird populations. We investigated these processes on two French tropical seabird islands of the western Indian Ocean, Europa and Juan de Nova, where black rats coexist with two different apex predator species (introduced cats and potentially native barn owls). The parallel use of several methods (diet analysis, stable isotopes, seabird monitoring) to identify trophic roles of rats revealed that the direct impact of rats on seabirds was particularly high on Europa where only rats and owls occur, with high consumption of chicks resulting in low breeding success for several seabird species. We also suggested that hyperpredation associated with top-down regulation of cats is occurring on Juan de Nova, although territoriality of cats may buffer this process. Conversely we found evidence that mesopredator release effect is unlikely, irrespective of the apex predator identity. Considering the most likely effects on both islands we provided recommendations on eradication priorities to mitigate the risk of local extinction that seabirds are currently facing.

Little evidence of top-predators biocontrol on invasive mesopredators

Allen, B. L., Allen, L. R., & Leung, L. K. P. 2014. Interactions between two naturalised invasive predators in Australia: are feral cats suppressed by dingoes?.Biological Invasions, 1-16.

Top-predators can play important roles in terrestrial food webs, fuelling speculation that top-predators might be used as biocontrol tools against invasive mesopredators. Feral cats are believed to be largely responsible for the current declines of native fauna across tropical northern Australia, where substantial beef cattle production occurs. Dingoes are known to impact cattle production there and are predicted to impact native fauna also. However, dingoes are forecasted to curtail the impacts of cats and reverse native fauna declines. We review (1) empirical studies investigating the relationships between dingoes and cats, and dingo control and cats, (2) records of cat remains in dingo diets, and (3) historical records of lethal dingo control using 1080-poisoned baits across Australia between 1999 and 2008 to show how two naturalised invasive species can interact in dynamic agro-ecological landscapes. From the 35 studies assessed, most reported no detectable relationship between dingoes and cats; negative or positive relationships were seldom detected. Dingoes do not appear to exclude cats beyond fine scales, but may alter cat activity periods under certain conditions. Cat remains were found in only 0.63 % of over 31,000 dingo diet records. Lethal dingo control occurs (in varying degrees) across about two-thirds of Australia and does not appear to substantially influence dingo-cat relationships. We conclude that the presently available data provides little evidence that bolstering dingo populations will reduce the impacts of cats. Much more work is needed to identify situations where top-predators might be used as effective biocontrol tools against invasive mesopredators in agro-ecological systems.

How the Macquarie Island parakeet became extinct

Taylor, R. H. (1979). How the Macquarie Island parakeet became extinct. New Zealand Journal of Ecology, 2, 42-45.

For 70 years following the discovery of Macquarie Island in 1810 the endemic parakeet Cyanoramphus novaezelandiae erythrotis remained plentiful, despite the introduction of cats (Felis catus) and other predators. The crucial factor in the bird's rapid disappearance between 1881 and 1890 appears to have been the successful liberation of rabbits (Oryctolagus cuniculus) in 1879. This led to great increases of feral cats and introduced wekas (Gallirallus australis) and presumably to greatly intensified predation on parakeets.

Changes in numbers of parakeets, rats,mice, feral rabbits, feral dogs, feral cats and wekas on Macquarie Island 1810-1920. Diagrammatic reconstructionfrom early accounts (Cumpston, 1968). Not to scale.

More on Macquarie island cats

Ecological restoration on Macquarie island

Copson, G., & Whinam, J. (2001). Review of ecological restoration programme on subantarctic Macquarie Island: pest management progress and future directions. Ecological Management & Restoration, 2(2), 129-138.
The establishment of exotic species of vascular flora and vertebrate fauna on subantarctic Macquarie Island since its discovery in 1810 has resulted in major changes in the biota. A management programme aims to reduce the numbers of exotic plant and animal species and assist with the recovery of pre-existing communities and processes. This paper reviews the integrated vertebrate pests management programme on Macquarie Island since 1974 and outlines future management considerations. As part of this programme, the responses of some native and exotic species of vascular flora and vertebrate fauna were monitored following control of European Rabbit (Oryctolagus cuniculus) numbers. Changes in the vegetation recorded over 10 years showed that approximately half of all the vascular species had benefited from rabbit grazing, including several which formed a major part of the rabbit’s diet. After rabbit control, some adversely affected plants responded rapidly to a reduction in grazing pressure while others will require an almost total cessation of grazing in order to re-establish their former distributions. With the decrease in rabbit numbers it was also necessary to control Feral Cats (Felis catus) due to their increased predation on native burrow-nesting birds. Feral Cat predation on introduced fauna also increased, one result of which was the eradication from the island of the introduced Weka (Gallirallus australis scotti). Reduced rabbit grazing is leading to re-establishment of the native Tall Tussock (Poa foliosa) grassland and with it the spread of the introduced Ship Rat (Rattus rattus). This review indicates that an integrated approach to pest management, with monitoring of the responses of both target and non-target species, is the most effective way to restore pre-existing communities and processes.

More on Macquarie island cats

Effect of feral dogs and cats on native mammals of Isla de Cedros

Cortés-Calva, P., Gallo-Reynoso, J. P., Delgadillo-Rodríguez, J., Lorenzo, C., & Álvarez-Castañeda, S. T. (2013). The Effect of Feral Dogs and Other Alien Species on Native Mammals of Isla de Cedros, Mexico. Natural Areas Journal,33(4), 466-473.

We report the status of alien species on Isla de Cedros, Mexico, and analyze the information from different years that together with a collaborative effort between academic biologists, Mexican governmental agencies, and local individuals has resulted in major information about the alien species on this island. We also report species richness of distinct endemic mammal species and the presence of feral dogs (Canis lupus familiaris Linnaeus), which is the principal problematic situation in this “Marine Priority Region.” The possible origin of feral dogs could be the migratory movement of stray dogs to find food in the inner part of the island, first moving to garbage dumps, reproducing in the area, and later hunting goats (Capra aegagrus hircus Linnaeus) in packs. The combination of the high density of stray dogs, urban and industrial food garbage dumps, and the large number of marine resources scattered along the seashore made ideal conditions for the establishment of feral dog packs that are affecting native species. The island does not have any natural mammal predator, but the presence of feral species, dogs and cats (Felis silvestris catus Schreber), could disturb the occurrence of endemic fauna as it has happened on other islands in the world.

Invasive species removal in whole ecosystem context

Zavaleta, E. S., Hobbs, R. J., & Mooney, H. A. (2001). Viewing invasive species removal in a whole-ecosystem context. Trends in Ecology & Evolution, 16(8), 454-459.

Eradications of invasive species often have striking positive effects on native biota. However, recent research has shown that species removal in isolation can also result in unexpected changes to other ecosystem components. These secondary effects will become more likely as numbers of interacting invaders increase in ecosystems, and as exotics in late stages of invasion eliminate native species and replace their functional roles. Food web and functional role frameworks can be used to identify ecological conditions that forecast the potential for unwanted secondary impacts. Integration of eradication into a holistic process of assessment and restoration will help safeguard against accidental, adverse effects on native ecosystems.

BOOK: Free-Ranging Dogs and Wildlife Conservation

Gompper, M.E. (Ed.) 2013. Free-Ranging Dogs and Wildlife Conservation. Oxford University Press. 

Table of contents

Luigi Boitani: Foreword
Matthew E. Gompper: Introduction: Outlining the Ecological Influences of a Subsidized, Domesticated Predator
1: Matthew E. Gompper: The Dog-Human-Wildlife Interface: Assessing the Scope of the Problem
2: Euan G. Ritchie, Mike Letnic, Christopher R. Dickman and Abi Tamim Vanak: Dogs as Predators and Trophic Regulators
3: Abi Tamim Vanak, Christopher R. Dickman, Eduardo A. Silva-Rodriguez, James R. A. Butler and Euan G. Ritchie: Top-dogs and Under-dogs: Competition between Dogs and Sympatric Carnivores
4: Michael A. Weston and Theodore Stankowich: Dogs as Agents of Disturbance
5: James R.A. Butler, John D.C. Linnell, Damian Morrant, Vidya Athreya, Nicolas Lescureux and Adam Mckeown: Dog Eat Dog, Cat Eat Dog: Social-ecological Dimensions and Implications of Dog Predation by Wild Carnivores
6: Darryn Knobel, James R. A. Butler, Tiziana Lembo, Rob Critchlow and Matthew E. Gompper: Dogs, Disease, and Wildlife
7: Jennifer A. Leonard, Jorge Echegaray, Ettore Randi and Carles Vilà: Impact of Hybridization with Domestic Dogs on the Conservation of Wild Canids
8: Ryan H. Boyko and Adam R. Boyko: Dog Conservation and the Population Genetic Structure of Dogs
9: Kurt VerCauteren, Michael Lavelle, Thomas M. Gehring, Jean-Marc Landry and Laurie Marker: Dogs as Mediators of Conservation Conflicts
10: Deborah A. (Smith) Woollett, Aimee Hurt and Ngaio Richards: The Current and Future Roles of Free-ranging Detection Dogs in Conservation Efforts
11: Jeremy Koster and Andrew Noss: Hunting Dogs and the Extraction of Wildlife as a Resource
12: Kelly K. Miller, Euan G. Ritchie and Michael A. Weston: The Human Dimensions of Dog-Wildlife Interactions

Controlling cats through the control of rabbits

Courchamp, F., Langlais, M., & Sugihara, G. (1999). Control of rabbits to protect island birds from cat predation. Biological Conservation, 89(2), 219-225.

Both introduced predators (e.g. domestic cats) and introduced small grazers (e.g. rabbits) are harmful to many island vertebrate species. The effects of cats on indigenous species are direct (predation), whereas the most obvious effects of rabbits are often indirect and in the longer term. Thus, in situations where both cats and rabbits are present, priority is frequently given to control of cats. However, the presence of rabbits can allow an increased predator population which can lead to extinction of the indigenous and less well adapted prey species, and increase the difficulty of predator control. Through a mathematical model, we show that control of introduced prey facilitates the control of the introduced predator population. Moreover, predator control may fail to protect the indigenous prey if control of the introduced prey is not undertaken simultaneously. Therefore, control of both introduced species is the best strategy.

Hyperpredation: Cat diet on a small Mediterranean island

Bonnaud, E., Bourgeois, K., Vidal, E., Kayser, Y., Tranchant, Y., & Legrand, J. (2007). Feeding ecology of a feral cat population on a small Mediterranean island. Journal of Mammalogy, 88(4), 1074-1081.

Domestic cats (Felis catus) have been introduced on many islands in the world and are responsible for much damage to native insular faunas. The worldwide success and spread of this opportunistic predator is generally associated with its trophic adaptability. We examined the diet of a long-established feral cat population on a small Mediterranean island through the analysis of 1,219 scats collected during a 4-year period. Our results confirm that feral cats are generalist predators, able to feed on a wide range of prey. However, only a few prey species formed the major part of its diet. Two introduced mammals and a Mediterranean endemic seabird provided 93% of the yearly biomass consumed by cats (ship rats, 70%; wild rabbits, 7%; and yelkouan shearwaters, 6%). Ship rats remained by far the staple prey for cats throughout the year, but the diet of feral cats was more diversified in spring and early summer, frequently including insects, reptiles, and migrant birds. Endemic yelkouan shearwaters were preyed upon most frequently in autumn and winter, that is, during the shearwaters' prelaying period. Because rats provide the majority of the food of cats, they could help to maintain or inflate this alien predator population with deleterious consequences to the endemic shearwater. A cat eradication campaign would help protect the population of shearwaters on this island.

Exotic mammals structure Australian biota

Davey, C., A. R. E. Sinclair, R. P. Pech, A. D. Arthur, C. J. Krebs, A. E. Newsome, D. Hik, R. Molsher, & K. Allcock (2006). Do exotic vertebrates structure the biota of Australia? An experimental test in New South Wales. Ecosystems,9(6), 992-1008

From 1993 to 2001, we conducted a series of experiments in a mixed grassland–woodland system in central New South Wales (NSW) to quantify the interactions between red foxes and their prey and competitors. Foxes were removed from two areas around the perimeter of Lake Burrendong, and data were collected from these areas and a nearby untreated area before, during, and after the period of fox control. The arrival of rabbit hemorrhagic disease (RHD) in 1996 provided an opportunity to examine the interactive effects of controlling foxes and rabbits. In this landscape, typical of central NSW, (a) the fox population was not affected by a large reduction in the abundance of rabbits, or vice versa; (b) the cat population declined in areas where foxes were removed after the large RHD-induced reduction in rabbit numbers, but there was no consistent response to the removal of foxes; (c) the abundance of some macropod species increased in response only to the combined removal of rabbits and foxes; (d) there were no consistent changes in the abundances of bird species in response to the removal of either foxes or rabbits, but there were clear habitat differences in bird species richness; and (e) there was likely to be an increase in woody plant species after the large reduction in rabbit populations by RHD. We conclude that (a) long-term field experiments (more than 3 years) are required to quantify the indirect consequences of controlling foxes and rabbits, and (b) single manipulations, such as fox control or rabbit control, are not necessarily sufficient for the conservation of remnant woodland communities in southeastern Australia.

Controversy on cat's eradication on Macquarie Island: predator or pathogen's release?

Bergstrom D, Lucieer A, Kiefer K, Wasley J, Belbin L, Pedersen T & Chown S (2009). Indirect effects of invasive species removal devastate World Heritage Island. Journal of Applied Ecology, 46: 73-81

A feral cat roams among baby penguins on Macquarie Island.
Photo: Geoff Copson/ Tasmanian NPWS

1. Owing to the detrimental impacts of invasive alien species, their control is often a priority for conservation management. Whereas the potential for unforeseen consequences of management is recognized, their associated complexity and costs are less widely appreciated.

2. We demonstrate that theoretically plausible trophic cascades associated with invasive species removal not only take place in reality, but can also result in rapid and drastic landscape-wide changes to ecosystems.

3. Using a combination of population data from of an invasive herbivore, plot-scale vegetation analyses, and satellite imagery, we show how a management intervention to eradicate a mesopredator has inadvertently and rapidly precipitated landscape-wide change on sub-Antarctic Macquarie Island. This happened despite the eradication being positioned within an integrated pest management framework. Following eradication of cats Felis catus in 2001, rabbit Oryctolagus cuniculus numbers increased substantially although a control action was in place (Myxoma virus), resulting in island-wide ecosystem effects.

http://ingervandyke.com/conservation/

4. Synthesis and applications. Our results highlight an important lesson for conservation agencies working to eradicate invasive species globally; that is, risk assessment of management interventions must explicitly consider and plan for their indirect effects, or face substantial subsequent costs. On Macquarie Island, the cost of further conservation action will exceed AU$24 million.

Dowding, J. E., Murphy, E. C., Springer, K., Peacock, A. J., & Krebs, C. J. (2009). Cats, rabbits, Myxoma virus, and vegetation on Macquarie Island: a comment on Bergstrom et al.(2009). Journal of Applied Ecology, 46(5), 1129-1132.

1. Eradication of a single pest species from a multiply invaded island system may have unpredicted and detrimental impacts.Bergstrom et al. (2009) describe damage to vegetation following an increase in the number of rabbits on Macquarie Island. They propose that the increase in rabbit numbers was caused solely by eradication of cats.

2. However, their modelling is flawed and their conclusion that cats were controlling rabbit numbers is unsupported. We suggest the increase was because of some combination of four factors: reduced releases of Myxoma virus, abundant food after 20 years of vegetation recovery, release from cat predation and climate variability.

3. Recent high numbers of rabbits on Macquarie Island are not unprecedented; vegetation has been damaged in the past but has recovered. Rabbit numbers appear to be in decline again in the absence of both cats and Myxoma releases, suggesting that other factors can contribute to regulation of rabbit numbers in this system.

4. We do not agree with the implication that pest management could have been better integrated. Eradication techniques for rodents and rabbits on an island the size of Macquarie were unavailable when cat eradication was deemed necessary. The benefits to seabirds of cat eradication have been rapid. Our analysis further highlights the complexity of multiply invaded island ecosystems.

Bergstrom, D. M., Lucieer, A., Kiefer, K., Wasley, J., Belbin, L., Pedersen, T. K., & Chown, S. L. (2009). Management implications of the Macquarie Island trophic cascade revisited: a reply to Dowding et al.(2009). Journal of Applied Ecology, 46(5), 1133-1136.

1. The management of non-indigenous species is not without its complications. In Bergstrom et al.’s (2009) study, we demonstrated that feral cats Felis catus on sub-Antarctic Macquarie Island were exerting top-down control on the feral rabbit Oryctolagus cuniculus population, and that the eradication of the cats led to a substantial increase in rabbit numbers and an associated trophic cascade.

2. Dowding et al. (2009) claim our modelling was flawed for various reasons, but primarily that a reduction in the application of the rabbit control agent, Myxoma virus, coinciding with cat removal, was a major driver of rabbit population release.

3. We explore this proposition (as well as others) by examining rates of Myxoma viral release between 1991 and 2006 (with an attenuation factor for the years, 2003–2006) in association with presence/absence of cats against two estimates of rabbit population size. Myxoma viral release was a significant factor in the lower estimates of rabbit population, but the effect was small, and was not significant for higher rabbit population estimates. By contrast, the presence or absence of cats remained highly significant for both estimates.

4.Synthesis and applications. We re-affirm our position that top-down control of rabbit numbers by cats, prior to their eradication, was occurring on Macquarie Island. Nonetheless, we agree with Dowding et al. (2009) that systems with multiple invasive species represent complex situations that require careful scrutiny. Such scrutiny should occur in advance of, during, and following management interventions.

More on Macquarie island cats

Direct and indirect impacts of alien predators on seabirds Islands

Seabird Islands: Ecology, Invasion, and Restoration

Some chapters available on line regarding predators, specially cats:

Drake, D. R.; Bodey, T.; Russell, J. C.; Towns, D. R.; Nogales, M.; Ruffino, L. (2011) Direct impacts of seabird predators on island biota other than seabirds. In: Mulder, C. P. H.; Anderson W. B.; Towns, D. R.; Bellingham, P. J. (eds) Seabird Islands: Ecology, Invasion, and Restoration. Oxford University Press, New York, pp. 91-132.

Russell, J. C. (2011) Indirect effect of introduced predators on seabird islands. In: Mulder, C. P. H.; Anderson W. B.; Towns, D. R.; Bellingham, P. J. (eds) Seabird Islands: Ecology, Invasion, and Restoration. Oxford University Press, New York, pp. 261-279.

Rabbit control to control cats

Glen, A., J. Cruz & R. Pech. 2013. Can rabbit control reduce feral cat numbers at a regional scale? Kararehe Kino, Vertebrate pest research, 21: 20-21

One of the most important factors affecting the abundance of predators is the availability of their prey. In New Zealand, introduced rabbits support populations of introduced predators, including feral cats. The abundance of rabbits may therefore affect the level of predation by cats on native birds, lizards and invertebrates.

...

By adopting a multispecies approach, in which rabbit and cat populations are targeted simultaneously, that both species can be supressed over large areas for long periods. This should have considerable benefits for pasture and for native vegetation and fauna.

Do wild dogs exclude foxes?

Mitchell, B. D., & Banks, P. B. (2005). Do wild dogs exclude foxes? Evidence for competition from dietary and spatial overlaps. Austral Ecology, 30(5), 581-591.

The management of wild canids (wild dogs/dingoes and foxes) presents a conservation dilemma for land managers across Australia. These canids are predators of wildlife and domestic stock but dingoes are considered native and anecdotal reports suggest that they may suppress foxes such that dingo/dog conservation may have a net benefit to wildlife. This study examines dietary and spatial interactions between wild dogs and foxes in the Greater Blue Mountains region of NSW to address the possibility of suppression through competitive exclusion by dogs on foxes. Predator diets were compared using faecal analysis as well as an analysis of 19 dietary studies from similar forest habitats in eastern Australia. Spatial relationships were examined using data from an extensive canid control programme. Diets of wild dogs and foxes showed a high degree of overlap in species taken, indicating potential for competition. But there was also evidence of resource partitioning with the size and arboreality of mammalian prey differing between the two predators. Wild dogs and foxes responded to different landscape-scale variation in the physical environment, but there was no clear evidence of large-scale differences in their distribution. At the fine scale there was a negative association between these predators that indicated possible temporal avoidance or localized habitat shifts. Therefore, there is evidence for dietary competition and fine-scale exclusion, but no support for landscape-scale exclusion of foxes by wild dogs in the Blue Mountains.

Predator preferences impact on native prey

Gaucel, S. & D. Pontier . 2005. How predator food preference can change the destiny of native prey in predator–prey systems. Biological Invasions, 7: 795–806.

The aim of this work is to develop and analyse a mathematical model for a predator-2 preys system arising in insular environments. We are interested in the evolution of a native prey population without behavioural traits to cope with predation or competition, after the introduction of alien species. Here, we consider a long living bird population with low fertility rate. We point out the effects of the preference of the predator for either juvenile or adult stages. In addition, we study the impact of alien prey introduction in such a model. We use a reaction-diffusion system with a singular logistic right hand side. The aim of this work is to bring interesting dynamics to the fore. As a first example, oscillatory behaviour takes place in the model without alien preys and when predators have an average preference coefficient. Introduction of alien preys can lead to species extinction.

Predation of cats on Mediterranean shearwater

BONNAUD, E., G. BERGER, K. BOURGEOIS, J. LEGRAND & E. VIDAL. 2012. Predation by cats could lead to the extinction of the Mediterranean endemic Yelkouan Shearwater Puffinus yelkouan at a major breeding site. Ibis, 154, 566–577


Feral cats are considered to be one of the main harmful invasive species for island species. Adult shearwaters are highly vulnerable to predation by cats. The population of the Yelkouan Shearwater Puffinus yelkouan, a species endemic to the Mediterranean, is predicted to decline, leaving only a few large breeding colonies, due to the invasion of cats. The impact of cats on the Shearwater population of Le Levant Island, one of the major breeding sites for this species, was evaluated by studying cat diet over a 2-year period. The predation rate obtained was then included in a Shearwater demographic model. Cats preyed upon rabbits, rats and Shearwaters, with a peak of predation on Shearwaters immediately upon their arrival at the colony. Cat predation was heavy and responsible for the yearly death of about 810–3241 birds. This could lead to the extinction of the Le Levant colony within the next four decades and perhaps within just a few years. Cat predation on prospecting individuals, a parameter essential to assess the real impact of predation, may not have an immediate effect on the Shearwater breeding population but can accelerate population extinction. Cat predation must be reduced or removed to prevent the extinction of one of the most important breeding sites for this species.

Rabbits killing birds revisited

Zhang, J., M Fan & Y. Kuang. 2006. Rabbits killing birds revisited. Biosciences, 203:100-123


We formulate and study a three-species population model consisting of an endemic prey (bird), an alien prey (rabbit) and an alien predator (cat). Our model overcomes several model construction problems in existing models. Moreover, our model generates richer, more reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rabbit or the cat when the bird is endangered. We confirm the existence of the hyperpredation phenomenon, which is a big potential threat to most endemic prey. Specifically, we show that, in an endemic prey–alien prey–alien predator system, eradication of introduced predators such as the cat alone is not always the best solution to protect endemic insular prey since predator control may fail to protect the indigenous prey when the control of the introduced prey is not carried out simultaneously.