Exploitation ecosystems and trophic cascades in non‐equilibrium systems: pasture – red kangaroo – dingo interactions in arid Australia

The exploitation ecosystems hypothesis (EEH) proposes that 1) plant biomass reflects the primary productivity of an ecosystem modified by the regulating effect of herbivory, and 2) herbivore abundance reflects the productivity of plants modified by the regulating effect of predation. Primary productivity thus determines the number of trophic levels in an ecosystem and the extent to which bottom–up and top–down regulation influence the biomass ratios of adjacent and non‐adjacent trophic levels (i.e. trophic cascading). We constructed an interactive model of plant (pasture), herbivore (red kangaroo Macropus rufus) and predator (dingo Canis lupus dingo), a system in which trophic cascades have been suggested to occur, and used it to test the effects of increasing stochastic variation in primary productivity and dingo culling on predictions of the EEH. The model contained four feedback loops: the predator–herbivore and herbivore–plant feedback loops, and the predator and plant density‐dependent feedback loops. The equilibrium conditions along the primary productivity gradient reproduced the three zones of trophic dynamics predicted by the EEH, plus an additional zone at productivities above which the maximum density of a predator is achieved due to social regulation: that zone is characterized by increasing herbivore density and decreasing plant biomass. Culling dingoes produced trophic cascades that were strongly attenuated at primary productivities below which the maximum density of dingoes was attained. Results were robust to uncertainty in kangaroo off‐take by dingoes and to the efficacy of dingo culling, but prey switching by dingoes from red kangaroos to reptiles would weaken trophic cascades. We conclude that social regulation of carnivores has important implications for expression of the EEH and trophic cascades, and that attenuation of trophic cascades increases with increasing stochasticity in primary productivity. Our model also provides a framework for understanding the conditions in which dingo‐mediated trophic cascades might be expected to occur, and generates testable predictions about the effects of higher dingo densities (e.g. by stopping culling or reintroduction to former range) on kangaroo and pasture dynamics.     

Strength of a Trophic Cascade Between an Apex Predator,Mammalian Herbivore and Grasses in a Desert Ecosystem Does Not Vary with Temporal Fluctuations in Primary Productivity

There has long been debate regarding the primacy of bottom-up and top-down effects as factors shaping ecosystems. The exploitation ecosystems hypothesis (EEH) predicts that predators indirectly benefit plants because their top-down effects limit herbivores’ consumption of plants, and that the strength of trophic cascade increases with increasing primary productivity. However, in arid environments, pulses of primary productivity produced by irregular rainfall events could decouple herbivore–plant and predator–prey dynamics if high conversion efficiency from seed biomass to consumers allows the rapid build-up of consumer populations. Here, we test predictions of the EEH in an arid environment. We measured activity/abundances of dingoes, red kangaroos and grasses, and diet of dingoes, in landscapes where dingoes were culled or not culled over 3 years. Dingo activity was correlated with rainfall, and their tracks were less frequent at culled sites. Kangaroo abundance was greater at sites where dingoes were culled and increased with rainfall in the previous 6 months. Grass cover was greater at sites where dingoes were not culled and increased with rainfall in the previous 3 months. During a period of average rainfall, dingoes primarily consumed rodents and increased their consumption of kangaroos during a period of drier conditions. Our results are consistent with the hypothesis that suppression of an apex predator triggers a trophic cascade, but are at odds with the EEH’s prediction that the magnitude of trophic cascades should increase with primary productivity. Our study demonstrates that temporal fluctuations in primary productivity can have effects on biomasses of plants and consumers which are in many ways analogous to those observed along spatial gradients of primary productivity.     

Does a top-predator provide an endangered rodent with refuge from an invasive mesopredator?

In arid environments, ecological refuges are often conceptualised as places where animal species can persist through drought owing to the localised persistence of moisture and nutrients. The mesopredator release hypothesis (MRH) predicts that reduced abundance of top-order predators results in an increase in the abundance of smaller predators (mesopredators) and consequently has detrimental impacts on the prey of the smaller predators. Thus according to the MRH, the existence of larger predators may provide prey with refuge from predation. In this study, we investigated how the abundance of an endangered rodent Notomys fuscus is affected by Australia's largest predator, the dingo Canis lupus dingo , introduced mesopredators, introduced herbivores, kangaroos and rainfall. Our surveys showed that N. fuscus was more abundant where dingoes occurred. Generalised linear modelling showed that N. fuscus abundance was associated positively with dingo activity and long-term annual rainfall and negatively with red fox Vulpes vulpes activity. Our results were consistent with the hypothesis that areas with higher rainfall and dingoes provide N. fuscus with refuge from drought and predation by invasive red foxes, respectively. Top-order predators, such as dingoes, could have an important functional role in broad-scale biodiversity conservation programmes by reducing the impacts of mesopredators.     

Are dingoes a trophic regulator in arid Australia? A comparison of mammal communities on either side of the dingo fence

The direct and indirect interactions that large mammalian carnivores have with other species can have far‐reaching effects on ecosystems. In recent years there has been growing interest in the role that Australia's largest terrestrial predator, the dingo, may have in structuring ecosystems. In this study we investigate the effect of dingo exclusion on mammal communities, by comparing mammal assemblages where dingoes were present and absent. The study was replicated at three locations spanning 300 km in the Strzelecki Desert. We hypothesized that larger species of mammal subject to direct interactions with dingoes should increase in abundance in the absence of dingoes while smaller species subject to predation by mesopredators should decrease in abundance because of increased mesopredator impact. There were stark differences in mammal assemblages on either side of the dingo fence and the effect of dingoes appeared to scale with body size. Kangaroos and red foxes were more abundant in the absence of dingoes while Rabbits and the Dusky Hopping‐mouse Notomys fuscus were less abundant where dingoes were absent, suggesting that they may benefit from lower red fox numbers in the presence of dingoes. Feral cats and dunnarts (Sminthopsis spp.) did not respond to dingo exclusion. Our study provides evidence that dingoes do structure mammal communities in arid Australia; however, dingo exclusion is also associated with a suite of land use factors, including sheep grazing and kangaroo harvesting that may also be expected to influence kangaroo and red fox populations. Maintaining or restoring populations of dingoes may be useful strategies to mitigate the impacts of mesopredators and overgrazing by herbivores.     

Ecologically functional landscapes and the role of dingoes as trophic regulators in south‐eastern Australia and other habitats

Large carnivores can play a pivotal role in maintaining healthy, balanced ecosystems. By suppressing the abundances and hence impacts of herbivores and smaller predators, top predators can indirectly benefit the species consumed by herbivores and smaller predators. Restoring and maintaining the ecosystem services that large carnivores provide has been identified as a critical step required to sustain biodiversity and maintain functional, resilient ecosystems. Recent research has shown that Australia's largest terrestrial predator, the Dingo (Canis lupus dingo), has strong effects on ecosystems in arid Australia and that these effects are beneficial for the conservation of small mammals and vegetation. Similarly, there is evidence from south‐eastern Australia that dingoes suppress the abundance of macropods and red Fox (Vulpes vulpes). It is likely that dingoes in south‐eastern Australia also generate strong indirect effects on the prey of foxes and macropods, as has been observed in the more arid parts of the continent. These direct and indirect effects of dingoes have the potential to be harnessed as passive tools to assist biodiversity conservation through the maintenance of ecologically functional dingo populations. However, research is required to better understand dingoes' indirect effects on ecosystems and the development of dingo management strategies that allow for both the preservation of dingoes and protection of livestock.     

Apex predator suppression is linked to restructuring of ecosystems via multiple ecological pathways

Removal of apex predators can drive ecological regime shifts owing to compensatory positive and negative population level responses by organisms at lower trophic levels. Despite evidence that apex predators can influence ecosystems though multiple ecological pathways, most studies investigating apex predators’ effects on ecosystems have considered just one pathway in isolation. Here, we provide evidence that lethal control of an apex predator, the dingo Canis dingo, drives shifts in the structure of Australia's tropical‐savannah ecosystems. We compared mammal assemblages and understorey structure at seven paired‐sites. Each site comprised an area where people poisoned dingoes and an area without dingo control. The effects of dingo control on mammals scaled with body size. Where dingoes were poisoned, we found greater activity of herbivorous macropods and feral cats, a mesopredator, but sparser understorey vegetation and lower abundances of native rodents. Our study suggests that ecological cascades arising from apex predators’ suppressive effects on herbivores and mesopredators occur simultaneously. Concordant effects of dingo removal across tropical‐savannah, forest and desert biomes suggest that dingoes once exerted ubiquitous top–down effects across Australia and provides support for calls that top–down forcing should be considered a fundamental process governing ecosystem structure.     

Does a top predator reduce the predatory impact of an invasive mesopredator on an endangered rodent?

The mesopredator release hypothesis (MRH) predicts that reduced abundance of top‐order predators results in an increase in the abundance of smaller predators (mesopredators) due to a reduction in intra‐guild predation and competition. The irruption of mesopredators that follows the removal of top‐order predators can have detrimental impacts on the prey of the mesopredators. Here we investigated the mechanisms via which the presence of a top‐order predator can benefit prey species. We tested predictions made according to the MRH and foraging theory by contrasting the abundances of an invasive mesopredator (red fox Vulpes vulpes) and an endangered prey species (dusky hopping mouse Notomys fuscus), predator diets, and N. fuscus foraging behaviour in the presence and absence of a top‐predator (dingo Canis lupus dingo). As predicted by the MRH, foxes were more abundant where dingoes were absent. Dietary overlap between sympatric dingoes and foxes was extensive, and fox was recorded in 1 dingo scat possibly indicating intra‐guild predation. Notomys fuscus were more likely to occur in fox scats than dingo scats and as predicted by the MRH N. fuscus were less abundant in the absence of dingoes. The population increase of N. fuscus following rainfall was dampened in the absence of dingoes suggesting that mesopredator release can attenuate bottom‐up effects, although it remains conceivable that differences in grazing regimes associated with dingo exclusion could have also influenced N. fuscus abundance. Notomys fuscus exhibited lower giving‐up densities in the presence of dingoes, consistent with the prediction that their perceived risk of predation would be lower and foraging efficiency greater in the presence of a top‐predator. Our results suggest that mesopredator suppression by a top predator can create a safer environment for prey species where the frequency of fatal encounters between predators and prey is reduced and the non‐consumptive effects of predators are lower.     

The distribution of deer biomass in North America supports the hypothesis of exploitation ecosystems

The hypothesis of exploitation ecosystems (EEH) predicts that, along a productivity gradient in terrestrial environments, predators will regulate herbivores at a relatively constant density whenever primary productivity exceeds 700 g m⁻² y⁻¹; under this threshold, or if predators are absent, forage production determines herbivore density. I tested EEH using the pattern of deer biomass distribution over North America, the dominant family of large herbivores. Deer biomass increased from the High Arctic to the north of the boreal forest and remained in the same range southward within the gray wolf range; for the same latitude, deer biomass increased by a factor of 5 in the absence of wolves. South of the wolf range, there existed a clear relationship between actual evapotranspiration, a proxy of primary productivity, and deer biomass. Highest deer densities occurred in the south-east of the continent where only white-tailed deer are present. The observed pattern lends support to EEH and suggests that the removal of large predators in southern North America may have imposed an unprecedented pressure on plants eaten by deer.     

Top predators as biodiversity regulators: the dingo Canis lupus dingo as a case study

Top‐order predators often have positive effects on biological diversity owing to their key functional roles in regulating trophic cascades and other ecological processes. Their loss has been identified as a major factor contributing to the decline of biodiversity in both aquatic and terrestrial systems. Consequently, restoring and maintaining the ecological function of top predators is a critical global imperative. Here we review studies of the ecological effects of the dingo Canis lupus dingo, Australia's largest land predator, using this as a case study to explore the influence of a top predator on biodiversity at a continental scale. The dingo was introduced to Australia by people at least 3500 years ago and has an ambiguous status owing to its brief history on the continent, its adverse impacts on livestock production and its role as an ecosystem architect. A large body of research now indicates that dingoes regulate ecological cascades, particularly in arid Australia, and that the removal of dingoes results in an increase in the abundances and impacts of herbivores and invasive mesopredators, most notably the red fox Vulpes vulpes. The loss of dingoes has been linked to widespread losses of small and medium‐sized native mammals, the depletion of plant biomass due to the effects of irrupting herbivore populations and increased predation rates by red foxes. We outline a suite of conceptual models to describe the effects of dingoes on vertebrate populations across different Australian environments. Finally, we discuss key issues that require consideration or warrant research before the ecological effects of dingoes can be incorporated formally into biodiversity conservation programs.     

Temporal and spatial trends in the abundances of an apex predator,introduced mesopredator and ground-nesting bird are consistent with the mesopredator release hypothesis

Apex predator extirpation has been identified as a key driver of biodiversity losses. The mesopredator release hypothesis (MRH) predicts that reduced abundance of apex predators results in an increase in the abundance and predatory impact of mesopredators. Here we test predictions made according to the MRH that an apex predator, the dingo (Canis dingo), benefits a small ground-nesting bird, the little button-quail (Turnix velox), by reducing the abundance of introduced mesopredators, the red fox (Vulpes vulpes) and feral cat (Felis catus). We also examined an alternative hypothesis that herbivore grazing negatively affects little button-quail abundance by reducing ground cover. To test our predictions we compared dingo, mesopredator, quail, herbivore and ground cover abundances and predator diets over a 25 month period and across a 10,000 km² region encompassing areas where dingoes were common and rare, pastoral properties, and conservation reserves. Little button-quails were primarily observed where dingoes were common and foxes rare. Cats were detected at low numbers throughout the sample area irrespective of the index abundance of little button-quails, dingoes or foxes. Birds occurred less frequently in dingo than fox or cat scats. Ground cover and herbivore grazing activity were poor correlates of little button-quail abundance. Our results are consistent with the hypothesis that apex predators’ mesopredator-suppressive effects translate to population-level benefits for a ground-nesting bird. Positive associations between the abundances of dingoes and small-prey species suggests that positive management of dingoes could be incorporated into broad-scale biodiversity conservation programs as a strategy to alleviate the predatory impacts of foxes.     

Changes in desert avifauna associated with the functional extinction of a terrestrial top predator

We investigated how long‐term suppression of populations of a top predator, the dingo Canis dingo, affected composition of sympatric avifauna in Australian deserts, by surveying bird assemblages across ~80 000 km² of arid dune‐fields on either side of the Dingo Barrier Fence (DBF; a 5614 km‐long fence separating ecosystems in which dingoes are abundant from ecosystems in which dingoes are functionally extinct). Using fourth‐corner modelling, incorporating species’ traits, we identified apparent declines of sedentary birds that nest in low vegetation and small birds that feed primarily on grass seed, and increases in scavenging birds associated with the functional extinction of dingoes. Occupancy differed between sites inside and outside the DBF in 13 bird species. We hypothesise that these differences in bird assemblages across the DBF result, in part, from increases in kangaroos Macropus spp. and red foxes Vulpes vulpes in arid landscapes where dingoes have been removed. Our study provides evidence that the functional extinction of a large terrestrial predator has had pervasive ecosystem effects, including shifts in composition of avian assemblages.     

Does a top predator suppress the abundance of an invasive mesopredator at a continental scale?

Aim We examined evidence for the mesopredator release hypothesis at a subcontinental scale by investigating the relationship between indices of abundance of the dingo Canis lupus dingo (top‐order predator) and the invasive red fox Vulpes vulpes (mesopredator) in three large regions across mainland Australia. The red fox is known to be one of the major threats to the persistence of small and medium‐sized native vertebrates across the continent. Location Australia. Methods Indices of abundance were calculated from three independently collected datasets derived from bounty returns and field surveys. Data were analysed using univariate parametric, semi‐parametric and nonparametric techniques. Results Predator abundance indices did not conform to a normal distribution and the relationships between dingo and fox abundance indices were not well described by linear functions. Semi‐parametric and nonparametric techniques revealed consistently negative associations between indices of dingo and fox abundance. Main conclusions The results provide evidence that mesopredator suppression by a top predator can be exerted at very large geographical scales and suggest that relationships between the abundances of top predators and mesopredators are not linear. Our results have broad implications for the management of canid predators. First, they suggest that dingoes function ecologically to reduce the activity or abundance of red foxes and thus are likely to dampen the predatory impacts of foxes. More generally, they provide support for the notion that the mesopredator‐suppressive effects of top predators could be incorporated into broad‐scale biodiversity conservation programmes in many parts of the world by actively maintaining populations of top predators or restoring them in areas where they are now rare. Determining the population densities at which the interactions of top predators become ecologically effective will be a critical goal for conservation managers who aim to maintain or restore ecosystems using the ecological interactions of top predators.     

Rarity of a top predator triggers continent-wide collapse of mammal prey: dingoes and marsupials in Australia

Top predators in terrestrial ecosystems may limit populations of smaller predators that could otherwise become over abundant and cause declines and extinctions of some prey. It is therefore possible that top predators indirectly protect many species of prey from excessive predation. This effect has been demonstrated in some small-scale studies, but it is not known how general or important it is in maintaining prey biodiversity. During the last 150 years, Australia has suffered the world's highest rate of mammal decline and extinction, and most evidence points to introduced mid-sized predators (the red fox and the feral cat) as the cause. Here, we test the idea that the decline of Australia's largest native predator, the dingo, played a role in these extinctions. Dingoes were persecuted from the beginning of European settlement in Australia and have been eliminated or made rare over large parts of the continent. We show a strong positive relationship between the survival of marsupials and the geographical overlap with high-density dingo populations. Our results suggest that the rarity of dingoes was a critical factor which allowed smaller predators to overwhelm marsupial prey, triggering extinction over much of the continent. This is evidence of a crucial role of top predators in maintaining prey biodiversity at large scales in terrestrial ecosystems and suggests that many remaining Australian mammals would benefit from the positive management of dingoes.     

Do dingoes suppress the activity of feral cats in northern Australia?

Large predators can have profound impacts on community composition. Not only do they directly affect prey abundance, they also indirectly affect prey abundance through their direct effects on smaller predators. In Australia, dingoes fill the role of a large predator and, in southern Australia, have clear impacts on introduced foxes. Their effect on introduced cats, however, is less clear. Here we present data from multiple sites across northern Australia (where foxes are absent), which reveal a negative correlation between cat and dingo activity. This relationship could arise because cats avoid areas where dingoes are active, or because cats are less abundant in areas with high dingo densities, or a combination of both. At a subset of our study sites, we experimentally reduced dingo (but not cat) abundance by poison baiting. This resulted in a 55% drop in dingo activity within 4 weeks of baiting, but without a compensatory increase in cat activity. This suggests the negative correlation between cat and dingo activity is not a simple consequence of cats reactively avoiding areas with higher dingo traffic, but rather, that there are fewer cats in areas where dingoes are more active. This study is a rare demonstration of the potential for dingoes to affect the behaviour and potentially the population size of feral cats, and therefore reduce the impact of feral cats on vulnerable native prey species.     

Resolving the value of the dingo in ecological restoration

There is global interest in restoring populations of apex predators, both to conserve them and to harness their ecological services. In Australia, reintroduction of dingoes (Canis dingo) has been proposed to help restore degraded rangelands. This proposal is based on theories and the results of studies suggesting that dingoes can suppress populations of prey (especially medium‐ and large‐sized herbivores) and invasive predators such as red foxes (Vulpes vulpes) and feral cats (Felis catus) that prey on threatened native species. However, the idea of dingo reintroduction has met opposition, especially from scientists who query the dingo's positive effects for some species or in some environments. Here, we ask ‘what is a feasible experimental design for assessing the role of dingoes in ecological restoration?’ We outline and propose a dingo reintroduction experiment—one that draws upon the existing dingo‐proof fence—and identify an area suitable for this (Sturt National Park, western New South Wales). Although challenging, this initiative would test whether dingoes can help restore Australia's rangeland biodiversity, and potentially provide proof‐of‐concept for apex predator reintroductions globally.     

More than Mere Numbers: The Impact of Lethal Control on the Social Stability of a Top-Order Predator

Population control of socially complex species may have profound ecological implications that remain largely invisible if only their abundance is considered. Here we discuss the effects of control on a socially complex top-order predator, the dingo (Canis lupus dingo). Since European occupation of Australia, dingoes have been controlled over much of the continent. Our aim was to investigate the effects of control on their abundance and social stability. We hypothesized that dingo abundance and social stability are not linearly related, and proposed a theoretical model in which dingo populations may fluctuate between three main states: (A) below carrying capacity and socially fractured, (B) above carrying capacity and socially fractured, or (C) at carrying capacity and socially stable. We predicted that lethal control would drive dingoes into the unstable states A or B, and that relaxation of control would allow recovery towards C. We tested our predictions by surveying relative abundance (track density) and indicators of social stability (scent-marking and howling) at seven sites in the arid zone subject to differing degrees of control. We also monitored changes in dingo abundance and social stability following relaxation and intensification of control. Sites where dingoes had been controlled within the previous two years were characterized by low scent-marking activity, but abundance was similar at sites with and without control. Signs of social stability steadily increased the longer an area was allowed to recover from control, but change in abundance did not follow a consistent path. Comparison of abundance and stability among all sites and years demonstrated that control severely fractures social groups, but that the effect of control on abundance was neither consistent nor predictable. Management decisions involving large social predators must therefore consider social stability to ensure their conservation and ecological functioning.     

Spatial variation in vegetation damage relative to primary productivity,small rodent abundance and predation

The relative importance of top‐down and bottom‐up mechanisms in shaping community structure is still a highly controversial topic in ecology. Predatory top‐down control of herbivores is thought to relax herbivore impact on the vegetation through trophic cascades. However, trophic cascades may be weak in terrestrial systems as the complexity of food webs makes responses harder to predict. Alternatively, top‐down control prevails, but the top‐level (predator or herbivore) changes according to productivity levels. Here we show how spatial variation in the occurrence of herbivores (lemmings and voles) and their predators (mustelids and foxes) relates with grazing damage in landscapes with different net primary productivity, generating two and three trophic level communities, during the 2007 rodent peak in northern Norway. Lemmings were most abundant on the unproductive high‐altitude tundra, where few predators were present and the impact of herbivores on vegetation was strong. Voles were most common on a productive, south facing slope, where numerous predators were present, and the impacts of herbivores on vegetation were weak. The impact of herbivores on the vegetation was strong only when predators were not present, and this cannot be explained by between‐habitat differences in the abundance of plant functional groups. We thus conclude that predators influence the plant community via a trophic cascade in a spatial pattern that support the exploitation ecosystems hypothesis. The responses to grazing also differed between plant functional groups, with implications for short and long‐term consequences for plant communities.     

Changes in the Spatial Configuration and Strength of Trophic Control Across a Productivity Gradient During a Massive Rodent Outbreak

Understanding the determinants of spatial and temporal differences in the relative strength of consumer–resource interactions is an important endeavour in ecology. Here, we explore the necessary conditions for temporal shifts in the relative strength of rodent–plant interactions in an area characterised by profound spatial differences in trophic control, with predator–prey interactions prevailing in productive habitats and rodent–plant interactions dominating unproductive habitats of the forest–tundra ecotone. We report data obtained during the exceptionally massive rodent outbreak of 2010–2012 in northernmost Fennoscandia, including an experimental manipulation of herbivore access to vegetation plots across a large-scale productivity gradient, multiple observational measures of plant–rodent interactions linked to rodent abundance data and a large-scale survey of breeding avian predators and mammalian predator activity. Unexpectedly, rodent grazing impacts documented during the rodent outbreak were uniformly strong across the landscape, regardless of habitat productivity. The runaway response in rodent populations was facilitated by a high population growth rate in the early phase of the outbreak due to the extended absence of predators in productive habitats, concomitant with an exceptionally long-lasting lemming outbreak in unproductive habitats. Our results showed that spatio-temporal variation in trophic control also occurs in ecosystems structured according to the exploitation ecosystems hypothesis and emphasises the importance of long-term studies to capture nonlinear and stochastic features that shape ecosystem functioning. In this context, the temporary release from top–down regulation in productive habitats caused strong grazing impacts that may be crucial for the resilience of tundra ecosystems under the threat of climate change-driven shrub encroachment.     

Not all predators are equal: a continent‐scale analysis of the effects of predator control on Australian mammals

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Bottom-up and top-down processes interact to modify intraguild interactions in resource-pulse environments

Top predators are declining globally, in turn allowing populations of smaller predators, or mesopredators, to increase and potentially have negative effects on biodiversity. However, detection of interactions among sympatric predators can be complicated by fluctuations in the background availability of resources in the environment, which may modify both the numbers of predators and the strengths of their interactions. Here, we first present a conceptual framework that predicts how top-down and bottom-up interactions may regulate sympatric predator populations in environments that experience resource pulses. We then test it using 2 years of remote-camera trapping data to uncover spatial and temporal interactions between a top predator, the dingo Canis dingo, and the mesopredatory European red fox Vulpes vulpes and feral cat Felis catus, during population booms, declines and busts in numbers of their prey in a model desert system. We found that dingoes predictably suppress abundances of the mesopredators and that the effects are strongest during declines and busts in prey numbers. Given that resource pulses are usually driven by large yet infrequent rains, we conclude that top predators like the dingo provide net benefits to prey populations by suppressing mesopredators during prolonged bust periods when prey populations are low and potentially vulnerable.