Responses to terrestrial nest predators by endemic and introduced Hawaiian birds

Birds free from nest predators for long periods may either lose the ability to recognize and respond to predators or retain antipredator responses if they are not too costly. How these alternate scenarios play out has rarely been investigated in an avian community whose members have different evolutionary histories. We presented models of two nest predators (rat and snake) and a negative control (tree branch) to birds on Hawai?i Island. Endemic Hawaiian birds evolved in the absence of terrestrial predators until rats were introduced approximately 1,000 years ago. Introduced birds evolved with diverse predator communities including mammals and snakes, but since their introduction onto the island approximately one century ago have been free from snake predation. We found that (a) endemic and introduced birds had higher agitation scores toward the rat model compared with the branch, and (b) none of the endemic birds reacted to the snake model, while one introduced bird, the Red‐billed Leiothrix (Leiothrix lutea), reacted as strongly to the snake as to the rat. Overall, endemic and introduced birds differ in their response to predators, but some endemic birds have the capacity to recognize and respond to introduced rats, and one introduced bird species retained recognition of snake predators from which they had been free for nearly a century, while another apparently lost that ability. Our results indicate that the retention or loss of predator recognition by introduced and endemic island birds is variable, shaped by each species' unique history, ecology, and the potential interplay of genetic drift, and that endemic Hawaiian birds could be especially vulnerable to introduced snake predators.     

A review of predation as a limiting factor for bird populations in mesopredator‐rich landscapes: a case study of the UK

The impact of increasing vertebrate predator numbers on bird populations is widely debated among the general public, game managers and conservationists across Europe. However, there are few systematic reviews of whether predation limits the population sizes of European bird species. Views on the impacts of predation are particularly polarised in the UK, probably because the UK has a globally exceptional culture of intensive, high‐yield gamebird management where predator removal is the norm. In addition, most apex predators have been exterminated or much depleted in numbers, contributing to a widely held perception that the UK has high numbers of mesopredators. This has resulted in many high‐quality studies of mesopredator impacts over several decades. Here we present results from a systematic review of predator trends and abundance, and assess whether predation limits the population sizes of 90 bird species in the UK. Our results confirm that the generalist predators Red Fox (Vulpes vulpes) and Crows (Corvus corone and C. cornix) occur at high densities in the UK compared with other European countries. In addition, some avian and mammalian predators have increased numerically in the UK during recent decades. Despite these high and increasing densities of predators, we found little evidence that predation limits populations of pigeons, woodpeckers and passerines, whereas evidence suggests that ground‐nesting seabirds, waders and gamebirds can be limited by predation. Using life‐history characteristics of prey species, we found that mainly long‐lived species with high adult survival and late onset of breeding were limited by predation. Single‐brooded species were also more likely to be limited by predation than multi‐brooded species. Predators that depredate prey species during all life stages (i.e. from nest to adult stages) limited prey numbers more than predators that depredated only specific life stages (e.g. solely during the nest phase). The Red Fox and non‐native mammals (e.g. the American Mink Neovison vison) were frequently identified as numerically limiting their prey species. Our review has identified predator–prey interactions that are particularly likely to result in population declines of prey species. In the short term, traditional predator‐management techniques (e.g. lethal control or fencing to reduce predation by a small number of predator species) could be used to protect these vulnerable species. However, as these techniques are costly and time‐consuming, we advocate that future research should identify land‐use practices and landscape configurations that would reduce predator numbers and predation rates.     

Predator control of ecosystem nutrient dynamics

Predators are predominantly valued for their ability to control prey, as indicators of high levels of biodiversity and as tourism attractions. This view, however, is incomplete because it does not acknowledge that predators may play a significant role in the delivery of critical life‐support services such as ecosystem nutrient cycling. New research is beginning to show that predator effects on nutrient cycling are ubiquitous. These effects emerge from direct nutrient excretion, egestion or translocation within and across ecosystem boundaries after prey consumption, and from indirect effects mediated by predator interactions with prey. Depending on their behavioural ecology, predators can create heterogeneous or homogeneous nutrient distributions across natural landscapes. Because predator species are disproportionately vulnerable to elimination from ecosystems, we stand to lose much more from their disappearance than their simple charismatic attractiveness.     

Behavioural responses of free‐ranging western grey kangaroos (Macropus fuliginosus) to olfactory cues of historical and recently introduced predators

Predation risk influences foraging decisions and time allocation of prey species, and may result in habitat shifts from potentially dangerous to safer areas. We examined a wild population of western grey kangaroos (Macropus fuliginosus) to test the efficacy of predator faecal odour in influencing time allocated to different behaviours and inducing changes in habitat use. Kangaroos were exposed to fresh faeces of a historical predator, the dingo (Canis lupus dingo), a recently introduced predator, the red fox (Vulpes vulpes), a herbivore (horse, Equus caballus) and an unscented control simultaneously. Kangaroos did not increase vigilance in predator‐scented areas. However, they investigated odour sources by approaching and sniffing; more time was spent investigating fox odour than control odours. Kangaroos then exhibited a clear anti‐predator response to predator odours, modifying their space use by rapidly escaping, then avoiding fox and dingo odour sources. Our results demonstrate that wild western grey kangaroos show behavioural responses to predator faeces, investigating then avoiding these olfactory cues of potential predation risk, rather than increasing general vigilance. This study contributes to our understanding of the impact of introduced mammalian predators on marsupial prey and demonstrates that a native Australian marsupial can recognize and respond to the odour of potential predators, including one that has been recently introduced.     

Large‐scale predator control increases population viability of a rare New Zealand riverine duck

The introduction of mammalian predators to oceanic islands has led to dramatic declines in the abundance of many native species. Conservation management of these species often relies on low‐cost predator control techniques that can be implemented over large scales. Assessing the effectiveness of such management techniques is difficult, but using population viability analyses (PVA), which identify the population growth rate (λ) and extinction risk of threatened species, may offer a solution. PVA provide the opportunity to compare the relative effectiveness of various management options and can identify knowledge gaps to prioritize research efforts. We used PVA to assess the population viability of whio (Hymenolaimus malacorhynchos), a rare riverine duck endemic to New Zealand. Current populations are threatened by introduced mammalian predators and are rapidly declining in both distribution and abundance. Whio conservation management is dominated by large‐scale, low‐intensity predator control, targeting introduced stoats (Mustela erminea). There is evidence that such control increases whio productivity but it is unknown if this increase is sufficient for long‐term population persistence. We undertook a stochastic PVA to assess the viability of whio populations under different management scenarios using data obtained from a 6‐year study of whio demographic responses to predator control. Populations with no predator control and low productivity will rapidly decline to extinction. Increasing productivity through predator control increased population viability but populations still showed a declining trajectory. A perturbation analysis showed that the growth rate of whio populations was largely driven by adult survival. Therefore, future research should target obtaining more robust estimates of adult survival, particularly how it is affected by predator control. Overall, our analysis indicated that large‐scale predator control increases the short‐term viability of whio populations but is insufficient for long‐term population persistence.     

The effectiveness of short‐term fox control in protecting a seasonally vulnerable species,the Eastern Long‐necked Turtle (Chelodina longicollis)

Reducing predation by introduced predators on seasonally vulnerable prey is of interest to biodiversity and game managers around the world. In Australia, the Red Fox (Vulpes vulpes) is a significant predator of freshwater turtle nests, destroying up to 93% of nests. We used a nonrandomized intervention study to assess the effectiveness of a short‐term (3‐week) but broad‐scale baiting operation in reducing the level of nest predation on artificial turtle nests around a complex lake system during a major flooding event in north‐western Victoria. Estimates of fox occupancy declined from 0.58 (0.44–0.70 95% CI) to 0.34 (0.21–0.46 95% CI) following fox control. Modelling of nest‐survival rates indicated there was no significant change in survival rates. Effective short‐term predator control to protect seasonally vulnerable prey is desirable and achievable. Knowledge of underlying predator density, predator–bait encounter and consumption rates, and the optimal duration of short‐term control is needed to reduce the risk to prey.     

Know thy enemy: Behavioural response of a native mammal (Rattus lutreolus velutinus) to predators of different coexistence histories

Abstract Predation is recognized as a major selective pressure influencing population dynamics and evolutionary processes. Prey species have developed a variety of predator avoidance strategies, not least of which is olfactory recognition. However, within Australia, European settlement has brought with it a number of introduced predators, perhaps most notably the red fox (Vulpes vulpes) and domestic cat (Felis catus), which native prey species may be unable to recognize and thus avoid due to a lack of coexistence history. This study examined the response of native Tasmanian swamp rats (Rattus lutreolus velutinus) to predators of different coexistence history (native predator‐ spotted‐tail quoll (Dasyurus maculatus), domestic cats and the recently introduced red fox). We used an aggregate behavioural response of R. l. velutinus to predator integumental odour in order to assess an overall behavioural response to predation risk. Rattus lutreolus velutinus recognized the integumental odour of the native quoll (compared with control odours) but did not respond to either cat or fox scent (compared with control odur). In contrast, analyses of singular behaviours resulted in the conclusion that rats did not respond differentially to either native or introduced predators, as other studies have concluded. Therefore, measuring risk assessment behaviours at the level of overall aggregate response may be more beneficial in understanding and analysing complex behavioural patterns such as predator detection and recognition. These results suggest that fox and cat introductions (and their interactive effects) may have detrimental impacts upon small native Tasmanian mammals due to lack of recognition and thus appropriate responses.     

Boreal predator co‐occurrences reveal shared use of seismic lines in a working landscape

Interspecific interactions are an integral aspect of ecosystem functioning that may be disrupted in an increasingly anthropocentric world. Industrial landscape change creates a novel playing field on which these interactions take place, and a key question for wildlife managers is whether and how species are able to coexist in such working landscapes. Using camera traps deployed in northern Alberta, we surveyed boreal predators to determine whether interspecific interactions affected occurrences of black bears (Ursus americanus), coyotes (Canis latrans), and lynx (Lynx canadensis) within a landscape disturbed by networks of seismic lines (corridors cut for seismic exploration of oil and gas reserves). We tested hypotheses of species interactions across one spatial‐only and two spatiotemporal (daily and weekly) scales. Specifically, we hypothesized that (1) predators avoid competition with the apex predator, gray wolf (Canis lupus), (2) they avoid competition with each other as intraguild competitors, and (3) they overlap with their prey. All three predators overlapped with wolves on at least one scale, although models at the daily and weekly scale had substantial unexplained variance. None of the predators showed avoidance of intraguild competitors or overlap with prey. These results show patterns in predator space use that are consistent with both facilitative interactions or shared responses to unmeasured ecological cues. Our study provides insight into how predator species use the working boreal landscape in relation to each other, and highlights that predator management may indirectly influence multiple species through their interactions.     

Does lethal control of top‐predators release mesopredators? A re‐evaluation of three Australian case studies

Top‐predators can sometimes be important for structuring fauna assemblages in terrestrial ecosystems. Through a complex trophic cascade, the lethal control of top‐predators has been predicted to elicit positive population responses from mesopredators that may in turn increase predation pressure on prey species of concern. In support of this hypothesis, many relevant research papers, opinion pieces and literature reviews identify three particular case studies as supporting evidence for top‐predator control‐induced release of mesopredators in Australia. However, many fundamental details essential for supporting this hypothesis are missing from these case studies, which were each designed to investigate alternative aims. Here, we re‐evaluate the strength of evidence for top‐predator control‐induced mesopredator release from these three studies after comprehensive analyses of associated unpublished correlative and experimental data. Circumstantial evidence alluded to mesopredator releases of either the European Red Fox (Vulpes vulpes) or feral Cat (Felis catus) coinciding with Dingo (Canis lupus dingo) control in each case. Importantly, however, substantial limitations in predator population sampling techniques and/or experimental designs preclude strong assertions about the effect of lethal control on mesopredator populations from these studies. In all cases, multiple confounding factors and plausible alternative explanations for observed changes in predator populations exist. In accord with several critical reviews and a growing body of demonstrated experimental evidence on the subject, we conclude that there is an absence of reliable evidence for top‐predator control‐induced mesopredator release from these three case studies. Well‐designed and executed studies are critical for investigating potential top‐predator control‐induced mesopredator release.     

Habitat functionality for the ecosystem service of pest control: reproduction and feeding sites of pests and natural enemies

• 1 Landscape management for enhanced natural pest control requires knowledge of the ecological function of the habitats present in the landscape mosaic. However, little is known about which habitat types in agricultural landscapes function as reproduction habitats for arthropod pests and predators during different times of the year.
• 2 We studied the arthropod assemblage on six crops and on the seven most abundant native plant species in two landscapes over 1 year in Australia. Densities of immature and adult stages of pests and their predators were assessed using beat sheet sampling.
• 3 The native plants supported a significantly different arthropod assemblage than crops. Native plants had higher predator densities than crops over the course of the year, whereas crops supported higher pest densities than the native plants in two out of four seasonal sampling periods. Crops had higher densities of immature stages of pests than native plants in three of four seasonal sampling periods, implying that crops are more strongly associated with pest reproduction than native plants. Densities of immature predators, excluding spiders, were not different between native plants and crops. Spiders were, however, generally abundant and densities were higher on native plants than on crops but, because some species disperse when immature, there is less certainty in identifying their reproduction habitat.
• 4 Because the predator to pest ratio on native plant species showed little variation, and spatial variation in arthropod assemblages was limited, the predator support function of native vegetation may be a general phenomenon. Incentives that maintain and restore native remnant vegetation can increase the predator to pest ratio at the landscape scale, which could enhance pest suppression in crops.

     

Soil nematode assemblages indicate the potential for biological regulation of pest species

In concept, regulation or suppression of target nematode pest species should be enhanced when an abundance of predator species is supported by ample availability of bacterial- fungal- and non-damaging plant-feeding prey species. We selected soils from natural and managed environments that represented different levels of resource availability and disturbance. In microcosm chambers of each soil, in its natural state or after heat defaunation, we introduced test prey species not already resident in the soils (Meloidogyne incognita and Steinernema feltiae). Survival of the test prey was determined after a 5-day bioassay exposure. Across the soils tested, predator abundance and biomass were greater in undisturbed soils with plentiful resources and lower in soils from agricultural sites. Suppressiveness to the two introduced species increased with both numerical abundance and metabolic footprint of the predator assemblages. The magnitude of the increase in suppressiveness was greater at low numbers of predators then dampened to an asymptotic level at greater predator abundance, possibly determined by temporal and spatial aspects of the bioassay system and/or satiation of the predators. The more resource-limited the predators were and the higher the metabolic predator footprint, the greater the suppressiveness. The applied implications of this study are that soil suppressiveness to pest species may be enhanced by increasing resources to predators, removing chemical and physical constraints to their survival and increase, and altering management practices so that predators and target prey are co-located in time and space.     

Complex interactions among mammalian carnivores in Australia, and their implications for wildlife management

Mammalian carnivore populations are often intensively managed, either because the carnivore in question is endangered, or because it is viewed as a pest and is subjected to control measures, or both. Most management programmes treat carnivore species in isolation. However, there is a large and emerging body of evidence to demonstrate that populations of different carnivores interact with each other in a variety of complex ways. Thus, the removal or introduction of predators to or from a system can often affect other species in ways that are difficult to predict. Wildlife managers must consider such interactions when planning predator control programmes. Integrated predator control will require a greater understanding of the complex relationships between species. In many parts of the world, sympatric species of carnivores have coexisted over an evolutionary time scale so that niche differentiation has occurred, and competition is difficult to observe. Australia has experienced numerous introductions during the past 200 years, including those of the red fox (Vulpes vulpes) and the feral cat (Felis catus). These species now exist in sympatry with native mammalian predators, providing ecologists with the opportunity to study their interactions without the confounding effects of coevolution. Despite an increasing body of observational evidence for complex interactions among native and introduced predators in Australia, few studies have attempted to clarify these relationships experimentally, and the interactions remain largely unacknowledged. A greater understanding of these interactions would provide ecologists and wildlife managers world-wide with the ability to construct robust predictive models of carnivore communities, and to identify their broader effects on ecosystem functioning. We suggest that future research should focus on controlled and replicated predator removal or addition experiments. The dingo (Canis lupus dingo), as a likely keystone species, should be a particular focus of attention.     

Conservation of native fauna in highly invaded systems: managing mammalian predators in New Zealand

Programs to conserve native fauna in invaded ecosystems often aim to reduce the impacts of alien predators. This approach can lead to unexpected outcomes in the native and the remaining invasive components of restored ecosystems. In New Zealand, suppression and eradication of invasive mammalian predators are well‐established conservation strategies, particularly on offshore islands and in mainland ecosanctuaries. Predator control has achieved important conservation gains over increasingly large areas but these can be offset by the ecological release of other uncontrolled pest species. In addition, novel ecosystems created by selective predator control and reintroductions of locally extinct or depleted native species may have unexpected trajectories as they evolve. Effective conservation requires new techniques for controlling entire suites of invasive predators over large areas, routine monitoring of the conservation outcomes of predator control, and better understanding of how modified, and in some cases reconstructed, seminatural ecosystems change when invasive predators are removed.     

Recognition and Response to Native and Novel Predators in the Largespring mosquitofish,Gambusia geiseri

The introduction of predator species into new habitats is an increasingly common consequence of human activities, and the persistence of native prey species depends upon their response to these novel predators. In this study, we examined whether the Largespring mosquitofish, Gambusia geiseri exhibited antipredator behavior and/or an elevation of circulating stress hormones (cortisol) to visual and chemical cues from a native predator, a novel predator, or a non‐predatory control fish. Prey showed the most pronounced antipredator response to the native predator treatment, by moving away from the stimulus, while the prey showed no significant changes in their vertical or horizontal position in response to the novel or non‐predator treatments. We also found no significant difference in water‐borne cortisol release rates following any of the treatments. Our results suggest the prey did not recognize and exhibit antipredator behavior to the novel predator, and we infer that this predator species could be detrimental if it expands into the range of this prey species. Further, our study demonstrates prey may not respond to an invasive predator that is phylogenetically, behaviorally, and morphologically dissimilar from the prey species' native predators.     

Risk mapping of illegal poisoning of avian and mammalian predators

Wild predators are targeted if they are perceived to affect game species or domestic animals. Over the last century, the direct persecution of birds of prey and mammalian carnivores has led to their widespread decline, even local extirpations. Many such cases involved the illegal use of poisoned bait. We used 1,305 detected poisoning events and 59 biophysical variables to construct a distribution model of illegal poisoning throughout Andalusia, southern Spain. We chose this region because the largest number of poisoning events recorded in Spain were detected in Andalusia during the period 1990–2005. Our results showed greater incidence of poisoning was correlated with areas of high predator richness and high wild rabbit hunting yields. Thus, we hypothesize that wildlife managers should be able to estimate current and potential poisoning areas using frequency of poisoning events data. Managers can then focus control within those areas identified as conflict zones and establish surveillance schemes that prevent the loss of wildlife within the targeted areas. Our results have potential application in strategic planning for conservation of vulnerable high-profile species such as birds of prey and mammalian carnivores in southern Spain and other regions. © 2012 The Wildlife Society.     

Resilience of ecosystem processes: a new approach shows that functional redundancy of biological control services is reduced by landscape simplification

Functional redundancy can increase the resilience of ecosystem processes by providing insurance against species loss and the effects of abundance fluctuations. However, due to the difficulty of assessing individual species’ contributions and the lack of a metric allowing for a quantification of redundancy within communities, few attempts have been made to estimate redundancy for individual ecosystem processes. We present a new method linking interaction metrics with metabolic theory that allows for a quantification of redundancy at the level of ecosystem processes. Using this approach, redundancy in the predation on aphids and other prey by natural enemies across a landscape heterogeneity gradient was estimated. Functional redundancy of predators was high in heterogeneous landscapes, low in homogeneous landscapes and scaled with predator specialisation. Our approach allows quantifying functional redundancy within communities and can be used to assess the role of functional redundancy across a wide variety of ecosystem processes and environmental factors.     

Predator–Primate Distribution,Activity, and Co-occurrence in Relation to Habitat and Human Activity Across Fragmented and Contiguous Forests in Northeastern Madagascar

Predator–primate interactions are understudied, yet predators have been shown to influence primate behavior, population dynamics, and spatial distribution. An understanding of these interactions is important for the successful management and conservation of these species. Novel approaches are needed to understand better the spatial relationships between predators and primates across changing landscapes. We combined photographic surveys of predators and humans with line-transect sampling of lemurs across contiguous and fragmented forests in Madagascar to 1) compare relative activity; 2) estimate probability of occupancy and detection; 3) estimate predator–primate and local people–primate co-occurrence; and 4) assess variables influencing these parameters across contiguous and fragmented forests. In fragmented (compared to contiguous) forest sites endemic predator and lemur activity were lower whereas introduced predator and local people activity were higher. Our two-species interaction occupancy models revealed a higher number of interactions among species across contiguous forest where predator and lemur occupancy were highest. Mouse lemurs show evidence of “avoidance” (SIF < 1.0) with all predator species (endemic and introduced) in contiguous forest whereas white-fronted brown lemurs show “attraction” (SIF > 1.0) with feral cats and local people in contiguous forest. Feral cats demonstrated the highest number of interactions with lemurs, despite their distribution being limited to only contiguous forest. Distance to forest edge and distance to nearby villages were important in predicting predator occupancy and detection. These results highlight the growing threat to endemic predators and lemurs as habitat loss and fragmentation increase throughout Madagascar. We demonstrate the effectiveness of a novel combination of techniques to investigate how predator species impact primate species across a gradient of forest fragmentation.     

Lethal interactions among forest‐grouse predators are numerous,motivated by hunger and carcasses,and their impacts determined by the demographic value of the victims

New vertebrate communities are emerging in Europe following the recovery of multiple native predators to highly anthropized landscapes where predator control is still prevalent. While the lack of reference points for these communities creates novel challenges for conservationists and wildlife managers, they also provide opportunities to further our understanding of species interactions. Despite a growing body of evidence, many aspects of interactions among predators remain poorly understood, impairing our ability to anticipate the effects of such changes in predator communities. Through a systematic literature review, we gathered all the available evidence concerning the existence, strength, and demographic impacts of lethal predator interactions among forest‐grouse predators in Europe. We found a highly interconnected predator community, with 44 pairwise lethal interactions among 12 taxa. Three of these resulted in some degree of population suppression of the victim, while another three did not. However, most interactions (38) have not been evaluated for population suppression. Additionally, we highlight how predators interact simultaneously with a large range of other predators and identified at least two further taxa possibly suppressed through the combined impacts of multiple predators. We propose that interactions causing demographic suppression are characterized by impacts on individuals with high survival elasticity and that they are motivated by food limitation and additionally, in mammals, by competition for carcasses. Predator interactions, and our still poor understanding of them, introduce large uncertainties to conservation actions based on the management of predator abundances, which should be carefully evaluated.     

Targeted control of widespread exotic species for biodiversity conservation: The Red Fox (Vulpes vulpes) in New South Wales, Australia

Summary   Widespread exotic species provide one of the greatest challenges to biodiversity conservation because they often have devastating impacts on native biota but are near impossible to eradicate. The Red Fox ( Vulpes vulpes ) is established across most of mainland Australia, where it has been linked to severe declines and extinctions of a broad suite of native fauna. A targeted approach to reducing the impacts of Foxes on biodiversity was instigated in New South Wales in 2001 under the New South Wales Fox Threat Abatement Plan. It is based on three simple steps. First, explicit priorities for Fox control are established by identifying which native species are at greatest risk from Fox predation and at which sites Fox control for these species is most critical. Second, high-frequency broad-area Fox-control programmes are established across all land tenures at these priority sites. Third, monitoring programmes are established to measure the response of targeted native fauna and Foxes to Fox control. Monitoring helps refine the priorities for control and the methods used over time. This approach provides a model for the strategic control of widespread exotic pests which threaten biodiversity.     

The landscape of fear as an emergent property of heterogeneity: Contrasting patterns of predation risk in grassland ecosystems

The likelihood of encountering a predator influences prey behavior and spatial distribution such that non‐consumptive effects can outweigh the influence of direct predation. Prey species are thought to filter information on perceived predator encounter rates in physical landscapes into a landscape of fear defined by spatially explicit heterogeneity in predation risk. The presence of multiple predators using different hunting strategies further complicates navigation through a landscape of fear and potentially exposes prey to greater risk of predation. The juxtaposition of land cover types likely influences overlap in occurrence of different predators, suggesting that attributes of a landscape of fear result from complexity in the physical landscape. Woody encroachment in grasslands furnishes an example of increasing complexity with the potential to influence predator distributions. We examined the role of vegetation structure on the distribution of two avian predators, Red‐tailed Hawk (Buteo jamaicensis) and Northern Harrier (Circus cyaneus), and the vulnerability of a frequent prey species of those predators, Northern Bobwhite (Colinus virginianus). We mapped occurrences of the raptors and kill locations of Northern Bobwhite to examine spatial vulnerability patterns in relation to landscape complexity. We use an offset model to examine spatially explicit habitat use patterns of these predators in the Southern Great Plains of the United States, and monitored vulnerability patterns of their prey species based on kill locations collected during radio telemetry monitoring. Both predator density and predation‐specific mortality of Northern Bobwhite increased with vegetation complexity generated by fine‐scale interspersion of grassland and woodland. Predation pressure was lower in more homogeneous landscapes where overlap of the two predators was less frequent. Predator overlap created areas of high risk for Northern Bobwhite amounting to 32% of the land area where landscape complexity was high and 7% where complexity was lower. Our study emphasizes the need to evaluate the role of landscape structure on predation dynamics and reveals another threat from woody encroachment in grasslands.