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Mesocarnivore community structuring in the presence of Africa's apex predator
Abstract
Apex predator reintroductions have proliferated across southern Africa, yet their ecological effects and proposed umbrella benefits of associated management lack empirical evaluations. Despite a rich theory on top-down ecosystem regulation via mesopredator suppression, a knowledge gap exists relating to the influence of lions (Panthera leo) over Africa's diverse mesocarnivore (less than 20 kg) communities. We investigate how geographical variation in mesocarnivore community richness and occupancy across South African reserves is associated with the presence of lions. An interesting duality emerged: lion reserves held more mesocarnivore-rich communities, yet mesocarnivore occupancy rates and evenness-weighted diversity were lower in the presence of lions. Human population density in the reserve surroundings had a similarly ubiquitous negative effect on mesocarnivore occupancy. The positive association between species richness and lion presence corroborated the umbrella species concept but translated into small differences in community size. Distributional contractions of mesocarnivore species within lion reserves, and potentially corresponding numerical reductions, suggest within-community mesopredator suppression by lions, probably as a result of lethal encounters and responses to a landscape of fear. Our findings offer empirical support for the theoretical understanding of processes underpinning carnivore community assembly and are of conservation relevance under current large-predator orientated management and conservation paradigms.
... The few studies that have assessed spatial patterns of such functional traits in tropical regions concluded that the functional composition of tropical forest mammals is largely consistent among regions, likely due to the age and stability of these forests, as well as similarities in climate and day length [4,7]. These studies, used species richness to determine functional composition and diversity [8,9] rather than 'occupancy'-defined as the proportion of sites occupied by a species [10]. ...
The structure of forest mammal communities appears surprisingly consistent across the continental tropics, presumably due to convergent evolution in similar environments. Whether such consistency extends to mammal occupancy, despite variation in species characteristics and context, remains unclear. Here we ask whether we can predict occupancy patterns and, if so, whether these relationships are consistent across biogeographic regions. Specifically, we assessed how mammal feeding guild, body mass and ecological specialization relate to occupancy in protected forests across the tropics. We used standardized camera-trap data (1002 camera-trap locations and 2-10 years of data) and a hierarchical Bayesian occupancy model. We found that occupancy varied by regions, and certain species characteristics explained much of this variation. Herbivores consistently had the highest occupancy. However, only in the Neotropics did we detect a significant effect of body mass on occupancy: large mammals had lowest occupancy. Importantly, habitat specialists generally had higher occupancy than gener-alists, though this was reversed in the Indo-Malayan sites. We conclude that habitat specialization is key for understanding variation in mammal occupancy across regions, and that habitat specialists often benefit more from protected areas, than do generalists. The contrasting examples seen in the Indo-Mala-yan region probably reflect distinct anthropogenic pressures.
... We show that in general, avian diversity in multi-use landscapes is maximized where local habitat heterogeneity is highest, but that to ensure the persistence of more sensitive or specialist species, conservation actions that seek to promote a healthy mix of local heterogeneity will have the broadest benefit across species communities. Indeed, this work emphasizes the complexity and contextdependency of biodiversity conservation and the need to balance maximizing the number of species with maximizing functional diversity (Curveira-Santos et al. 2021). Our approach to quantifying landscapes with multiple gradients of landscape variation that intuitively map to distinct sources of anthropogenic influence offers a promising approach to achieve such ends and prioritize landscapes for conservation. ...
Context
Identifying factors driving patterns of species communities in heterogenous human-dominated landscapes remains elusive despite extensive research. Biodiversity is thought to decrease with habitat modification, as sensitive species are lost. Conversely, diversity has also been shown increase at moderate levels of landscape modification where greater habitat heterogeneity supports a diverse suite of species.
Objectives
We explore patterns of avian diversity and abundance in heterogenous landscapes using a novel integration of multiple dimensional gradients of human-mediated modification.
Methods
We attempt to identify aspects of landscape heterogeneity driving patterns of avian diversity and abundance in agro-urban–rural systems. Specifically, we utilize an intuitive multi-dimensional gradient distinguishing between two axes of human-influence, variation in the built environment (hard–soft) and in agricultural development (green–brown). We use these as covariates in community N-mixture models to describe variation in species abundance and diversity.
Results
Avian richness was greatest in more heterogeneous regions of the landscape. Responses of individual species were variable, with sensitive species declining, while generalist species increased, leading to higher overall diversity in human-dominated regions.
Conclusions
Species abundance and diversity is maximized in more heterogeneous parts of landscape mosaics. By characterizing distinct axes of human influence that capture spectrum of land use, we can identify differential effects confounded in traditional landscape metrics. Critically, we demonstrate that multi-dimensional landscape gradients provide a more nuanced understanding of how patterns of biodiversity emerge. Acknowledging that biodiversity is not always negatively impacted by habitat modification offers encouraging insight to guide conservation and management in human-dominated landscapes.
... The fact that several African carnivores were involved in IGK events as both the aggressor and the victim challenges the classic two-rank view on mesopredator suppression (Prugh et al. 2009) and lends further support to potential multilevel cascading effects in species-rich carnivore guilds (Levi and Wilmers 2012). In addition, the observed prevalence of large-to-small IGK events expands the multilevel theory by suggesting possibly stronger than predicted net suppressive effects of large carnivores, as highlighted by Prugh and Sivy (2020) and suggested empirically for lion suppression of African mesocarnivore species (Curveira-Santos et al. 2021b). We encourage future research that revisits top-down structuring of carnivore guilds in other species-rich systems containing large hyperpredatory carnivores (e.g., tiger [Panthera tigris] and leopard in Southern Asia or jaguars [Panthera onca] and pumas [Panthera concolor] in South America). ...
Theory on intraguild killing (IGK) is central to mammalian carnivore community ecology and top‐down ecosystem regulation. Yet, the cryptic nature of IGK hinders empirical evaluations. Using a novel data source ‐ online photographs of interspecific aggression between African carnivores ‐ we revisited existing predictions about the extent and drivers of IGK. Compared to seminal reviews, our constructed IGK network yielded 11 more species and nearly twice as many interactions. The extent of interactions increased 37% when considering intraguild aggression (direct attack) as a precursor of killing events. We show that IGK occurs over a wider range of body‐mass ratios than predicted by standing competition‐based views, with highly asymmetrical interactions being pervasive. Evidence that large species, particularly hypercarnivore felids, target sympatric carnivores with a wide range of body sizes suggests that current IGK theory is incomplete, underestimating alternative competition pathways and the role of predatory and incidental killing. Our findings reinforce the potential for IGK‐mediated cascades in species‐rich assemblages and community‐wide suppressive effects of large carnivores.
Fires are common in many ecosystems worldwide, and are frequently used as a management tool. Although the responses of herbivores to fire have been well‐studied, the responses of carnivores to fire remain unclear. In particular, post‐fire habitat changes, and the associated changes in prey availability, might affect the coexistence or competition of carnivore species within the larger carnivore community, but few studies have focused on how fires influence multiple carnivore species simultaneously. Using South African carnivores as our focal community, we explored relative changes in carnivore intensity of use in post‐fire landscapes associated with hypothesized changes in prey availability and top‐down suppression. We monitored carnivore intensity of use in relation to prescribed burning using camera traps, with a Before‐After‐Control‐Impact study design. We analyzed the camera trap data using community N‐mixture models to understand how individual species, as well as the carnivore guild as a whole, respond to burning. Changes in carnivore intensity of use in response to prescribed burns were not uniform; however, no species decreased intensity of use of post‐fire landscapes. The apex predator, the lion (Panthera leo), increased use of prey‐rich burnt areas, but other large carnivore species exhibited neutral responses to fire despite the associated prey increase. Responses of medium‐ and small‐sized carnivores were species‐specific, and included both neutral and positive responses. Positive responses to fire by lions and herbivores were short‐lived, and did not persist a year after burning occurred. Synthesis and Applications: Our results indicate that fire does not promote carnivore coexistence by creating conditions for all carnivores to increase use of burned areas, but that it also likely does not result in spatial avoidance of subordinate predators. Instead, fires might cause a suppression of opportunities for subordinate large carnivores because they need to avoid the apex predator, rather than take advantage of short‐term increased hunting opportunities in recently burned areas. Our results highlight the complexity of understanding species‐specific and community‐level responses of carnivores to fire, and overlooked ecological effects of its use as a management tool.
Interactions among terrestrial carnivores involve a complex interplay of competition, predation and facilitation via carrion provisioning, and these negative and positive pathways may be closely linked. Here, we developed an integrative framework and synthesized data from 256 studies of intraguild predation, scavenging, kleptoparisitism and resource availability to examine global patterns of suppression and facilitation. Large carnivores were responsible for one third of mesocarnivore mortality (n = 1,581 individuals), and intraguild mortality rates were superadditive, increasing from 10.6% to 25.5% in systems with two vs. three large carnivores. Scavenged ungulates comprised 30% of mesocarnivore diets, with larger mesocarnivores relying most heavily on carrion. Large carnivores provided 1,351 kg of carrion per individual per year to scavengers, and this subsidy decreased at higher latitudes. However, reliance on carrion by mesocarnivores remained high, and abundance correlations among sympatric carnivores were more negative in these stressful, high-latitude systems. Carrion provisioning by large carnivores may therefore enhance suppression rather than benefiting mesocarnivores. These findings highlight the synergistic effects of scavenging and predation risk in structuring carnivore communities, suggesting that the ecosystem service of mesocarnivore suppression provided by large carnivores is strong and not easily replaced by humans.
Camera traps deployed in grids or stratified random designs are a well‐established survey tool for wildlife but there has been little evaluation of study design parameters.
We used an empirical subsampling approach involving 2225 camera deployments run at 41 study areas around the world to evaluate three aspects of camera trap study design (number of sites, duration and season of sampling) and their influence on the estimation of three ecological metrics (species richness, occupancy, detection rate) for mammals.
We found that 25‐35 camera sites were needed for precise estimates of species richness, depending on scale of the study. The precision of species‐level estimates of occupancy (ψ) was highly sensitive to occupancy level, with <20 camera sites needed for precise estimates of common (ψ>0.75) species, but more than 150 camera sites likely needed for rare (ψ<0.25) species. Species detection rates were more difficult to estimate precisely at the grid level due to spatial heterogeneity, presumably driven by unaccounted habitat variability factors within the study area. Running a camera at a site for 2 weeks was most efficient for detecting new species, but 3‐4 weeks were needed for precise estimates of local detection rate, with no gains in precision observed after 1 month. Metrics for all mammal communities were sensitive to seasonality, with 37‐50% of the species at the sites we examined fluctuating significantly in their occupancy or detection rates over the year. This effect was more pronounced in temperate sites, where seasonally sensitive species varied in relative abundance by an average factor of 4‐5, and some species were completely absent in one season due to hibernation or migration.
We recommend the following guidelines to efficiently obtain precise estimates of species richness, occupancy and detection rates with camera trap arrays: run each camera for 3‐5 weeks across 40‐60 sites per array. We recommend comparisons of detection rates be model‐based and include local covariates to help account for small‐scale variation. Furthermore, comparisons across study areas or times must account for seasonality, which could have strong impacts on mammal communities in both tropical and temperate sites.
Abstract Globally, human activities have led to the impoverishment of species assemblages and the disruption of ecosystem function. Determining whether this poses a threat to future ecosystem stability necessitates a thorough understanding of mechanisms underpinning community assembly and niche selection. Here, we tested for niche segregation within an African small carnivore community in Kibale National Park, Uganda. We used occupancy modeling based on systematic camera trap surveys and fine‐scale habitat measures, to identify opposing preferences between closely related species (cats, genets, and mongooses). We modeled diel activity patterns using kernel density functions and calculated the overlap of activity periods between related species. We also used co‐occupancy modeling and activity overlap analyses to test whether African golden cats Caracal aurata influenced the smaller carnivores along the spatial and/or temporal axes. There was some evidence that related species segregated habitat and activity patterns. Specialization was particularly strong among forest species. The cats and genets partitioned habitat, while the mongooses partitioned both habitat and activity period. We found little evidence for interference competition between African golden cats and other small carnivores, although weak interference competition was suggested by lower detection probabilities of some species at stations where African golden cats were present. This suggests that community assembly and coexistence in this ecosystem are primarily driven by more complex processes. The studied carnivore community contains several forest specialists, which are typically more prone to localized extinction. Preserving the observed community assemblage will therefore require the maintenance of a large variety of habitats, with a particular focus on those required by the more specialized carnivores.
Due to the strong individual cost of being predated, potential prey species alter their behavior and physiology in response to predation risk. Such alterations may cause major indirect consequences on prey populations that are additive to the direct demographic effects caused by prey being killed. However, although earlier studies showed strong general effects of the presence of apex predators, recent data suggest that indirect effects may be highly context dependent and not consistently present. We combined behavioral data with data on endocrine stress and stable isotopes to assess landscape level effects of lion (Panthera leo) presence on two prey species in South Africa, impala (Aepyceros melampus) and blue wildebeest (Connochaetes taurinus). We also evaluated if there was any seasonal variation in such effects. In addition, we provide results from a physiological validation for an enzyme-linked immunoassay (EIA) that can be used for non-invasive monitoring of glucocorticoid stress metabolite concentrations in impala from fecal pellets. We did not find any significant differences in vigilance behavior, fecal glucocorticoid metabolite concentrations, δ13C values or isotope niche breadth between animals living with and without lions for either species. However, wildebeest living in a reserve with lions spent more time foraging compared to wildebeest in a lion-free environment, but only during the wet season. Values of fecal δ15N suggest a shift in habitat use, with impala and wildebeest living with lions potentially feeding in less productive areas compared to animals living without lions. For both species, characteristics of the social groups appeared to be more important than individual characteristics for both foraging and vigilance behavior. Our results highlight that antipredator responses may be highly dynamic and scale-dependent. We urge for further studies that quantify at what temporal and spatial scales predation risk is causing indirect effects on prey populations.
Protected areas (PAs) play an important role in conserving biodiversity and providing ecosystem services, yet their effectiveness is undermined by funding shortfalls. Using lions (Panthera leo) as a proxy for PA health, we assessed available funding relative to budget requirements for PAs in Africa's savannahs. We compiled a dataset of 2015 funding for 282 state-owned PAs with lions. We applied three methods to estimate the minimum funding required for effective conservation of lions, and calculated deficits. We estimated minimum required funding as $978/km2 per year based on the cost of effectively managing lions in nine reserves by the African Parks Network; $1,271/km2 based on modeled costs of managing lions at ≥50% carrying capacity across diverse conditions in 115 PAs; and $2,030/km2 based on Packer et al.'s [Packer et al. (2013) Ecol Lett 16:635-641] cost of managing lions in 22 unfenced PAs. PAs with lions require a total of $1.2 to $2.4 billion annually, or ∼$1,000 to 2,000/km2, yet received only $381 million annually, or a median of $200/km2 Ninety-six percent of range countries had funding deficits in at least one PA, with 88 to 94% of PAs with lions funded insufficiently. In funding-deficit PAs, available funding satisfied just 10 to 20% of PA requirements on average, and deficits total $0.9 to $2.1 billion. African governments and the international community need to increase the funding available for management by three to six times if PAs are to effectively conserve lions and other species and provide vital ecological and economic benefits to neighboring communities.
1.Although interspecific competition plays a principle role in shaping species behaviour and demography, little is known about the population‐level outcomes of competition between large carnivores, and the mechanisms that facilitate coexistence. 2.We conducted a multi‐landscape analysis of two widely distributed, threatened large carnivore competitors to offer insight into coexistence strategies and assist with species‐level conservation. 3.We evaluated how interference competition affects occupancy, temporal activity and population density of a dominant competitor, the lion (Panthera leo), and its subordinate competitor, the leopard (Panthera pardus). We collected camera‐trap data over three years in ten study sites covering 5,070 km2. We used multispecies occupancy modelling to assess spatial responses in varying environmental and prey conditions and competitor presence, and examined temporal overlap and the relationship between lion and leopard densities across sites and years. 4.Results showed that both lion and leopard occupancy was independent of – rather than conditional on – their competitor's presence across all environmental covariates. Marginal occupancy probability for leopard was higher in areas with more bushy, ‘hideable’ habitat, human (tourist) activity and topographic ruggedness, whereas lion occupancy decreased with increasing hideable habitat and increased with higher abundance of very large prey. Temporal overlap was high between carnivores and there was no detectable relationship between species densities. 5.Lions pose a threat to the survival of individual leopards, but they exerted no tractable influence on leopard spatial or temporal dynamics. Furthermore, lions did not appear to suppress leopard populations, suggesting that intraguild competitors can coexist in the same areas without population decline. Aligned conservation strategies that promote functioning ecosystems, rather than target individual species, are therefore advised to achieve cost‐ and space‐effective conservation. This article is protected by copyright. All rights reserved.
Occupancy-abundance (OA) relationships are a foundational ecological phenomenon and field of study, and occupancy models are increasingly used to track population trends and understand ecological interactions. However, these two fields of ecological inquiry remain largely isolated, despite growing appreciation of the importance of integration. For example, using occupancy models to infer trends in abundance is predicated on positive OA relationships. Many occupancy studies collect data that violate geographical closure assumptions due to the choice of sampling scales and application to mobile organisms, which may change how occupancy and abundance are related. Little research, however, has explored how different occupancy sampling designs affect OA relationships. We develop a conceptual framework for understanding how sampling scales affect the definition of occupancy for mobile organisms, which drives OA relationships. We explore how spatial and temporal sampling scales, and the choice of sampling unit (areal-, vs. point-sampling), affect OA relationships. We develop predictions using simulations, and test them using empirical occupancy data from remote cameras on 11 medium-large mammals. Surprisingly, our simulations demonstrate that when using point sampling, OA relationships are unaffected by spatial sampling grain (i.e. cell size). In contrast, when using areal-sampling (e.g. species atlas data), OA relationships are affected by spatial grain. Furthermore, OA relationships are also affected by temporal sampling scales, where the curvature of the OA relationship increases with temporal sampling duration. Our empirical results support these predictions, showing that at any given abundance, the spatial grain of point sampling does not affect occupancy estimates, but longer surveys do increase occupancy estimates. For rare species (low occupancy), estimates of occupancy will quickly increase with longer surveys, even while abundance remains constant. Our results also clearly demonstrate that occupancy for mobile species without geographical closure is not true occupancy. The independence of occupancy estimates from spatial sampling grain depends on the sampling unit. Point-sampling surveys can, however, provide unbiased estimates of occupancy for multiple species simultaneously, irrespective of home-range size. The use of occupancy for trend monitoring needs to explicitly articulate how the chosen sampling scales define occupancy and affect the occupancy-abundance relationship. This article is protected by copyright. All rights reserved.
Top predators can suppress mesopredators by killing them, competing for resources and instilling fear, but it is unclear how suppression of mesopredators varies with the distribution and abundance of top predators at large spatial scales and among different ecological contexts. We suggest that suppression of mesopredators will be strongest where top predators occur at high densities over large areas. These conditions are more likely to occur in the core than on the margins of top predator ranges. We propose the Enemy Constraint Hypothesis, which predicts weakened top-down effects on mesopredators towards the edge of top predators' ranges. Using bounty data from North America, Europe and Australia we show that the effects of top predators on mesopredators increase from the margin towards the core of their ranges, as predicted. Continuing global contraction of top predator ranges could promote further release of mesopredator populations, altering ecosystem structure and contributing to biodiversity loss.
Top predators often have cascading effects on mesopredator communities by driving behavioural changes. Using camera-trapping surveys, we explored the site-detection probability of sympatric predators and temporal overlap and examined behavioural patterns to explore hypotheses of carnivore guild interactions between and within large and small predators in the presence/absence of lion (Panthera leo) in open and closed habitat cover. We used single-season two-species occupancy models to test inter-predator interactions at 205 camera sites spread across five Protected Areas of the Maputaland Conservation Unit, South Africa. These data showed the respective associations between the presence of large carnivores and smaller carnivores. We observed that leopard (Panthera pardus) and hyena (Crocuta crocuta) tended to avoid interference encounters, as they were less likely co-detected at the same sites. There was a decrease in detection of leopard and hyena as a function of lion presence. Small predators such as the group honey badger (Mellivora capensis)-striped polecat (Ictonyx striatus) and the slender mongoose (Herpestes sanguineus) were detected less often at cameras where leopards were detected. Detection probabilities of the group badger-polecat and slender mongoose were much higher in the closed habitat than in open habitat where leopards were detected. At camera sites where hyenas were detected, badger-polecat and genet (Genetta tigrina) detection probability was much higher in the closed habitat than open habitat. Slender mongoose overlapped less temporally with large predators while others did not. Our study showed that large predator guilds can affect the probability of detecting subordinate mesopredators; therefore, reintroduction of large carnivores can have a cascading effect on subordinate carnivores, and it is necessary to consider this effect when planning recovery programmes for carnivore conservation.
Significance statement
We think this study is of importance and interest as top predators often shape mesopredator communities by inducing apparent avoidance behaviour based on associations between the presence of large carnivores and smaller carnivores. As a consequence, smaller predators use closed habitat to minimize the risk of larger predators due to intraguild interference interaction. We explored behavioural patterns of sympatric predators’ site detection probability and temporal overlap and examined hypotheses about carnivore guild interactions between leopard and spotted hyena, these two and small predators with and without lion in open and closed habitat cover. Reintroduction of one carnivore population can have cascading effects on the other, and this nature of consequences needs to be accounted when planning conservation or species recovery programmes. Therefore, we extended our study to explore these important aspects. Our study is novel as there are no studies documenting species interactions between/within large and small predators from co-occurrence patterns in South Africa.
Interactions between large carnivores and other species may be responsible for impacts that are disproportionately large relative to their density. Context-dependent interactions between species are common but often poorly described. Caution must be expressed in seeing apex predators as ecological saviours because ecosystem services may not universally apply, particularly if inhibited by anthropogenic activity. This review examines how the impacts of large carnivores are affected by four major contexts (species assemblage, environmental productivity, landscape, predation risk) and the potential for human interference to affect these contexts. Humans are the most dominant landscape and resource user on the planet and our management intervention affects species composition, resource availability, demography, behaviour and interspecific trophic dynamics. Humans can impact large carnivores in much the same way these apex predators impact mesopredators and prey species - through density-mediated (consumptive) and trait/behaviourally-mediated (non-consumptive) pathways. Mesopredator and large herbivore suppression or release, intraguild competition and predation pressure may all be affected by human context. The aim of restoring ‘natural’ systems is somewhat problematic and not always pragmatic. Interspecific interactions are influenced by context, and humans are often the dominant driver in forming context. If management and conservation goals are to be achieved then it is pivotal to understand how humans influence trophic interactions and how trophic interactions are affected by context. Trade-offs and management interventions can only be implemented successfully if the intricacies of food webs are properly understood.
An enduring challenge in ecology is to understand what drives spatial variation in the size and structure of communities. The ability to count the number of species present at a location is hindered by the fact that not all species are equally detectable, and invariably some go completely undetected. This makes comparing species richness across distinct spatial units (or regions) problematic as sources of error are usually unaccounted for in simple enumerations of species. Multi-species occupancy models explicitly incorporate a model for this observation uncertainty and provide a framework for estimating community size when detection is imperfect. Currently, however, the model is restricted to estimating the number of species at only a single region of interest. In this paper we extend the multi-species occupancy model to accommodate data collected across multiple regions of interest (e.g., reserves or biomes) allowing for joint estimation of region-specific community size. Moreover, our approach allows species richness to be modeled as a function of region-specific covariates thus providing a mechanism for testing hypotheses about why and how species richness varies in space. Here, we first demonstrate the value of the joint multi-region approach using simulations to compare model performance to the more traditional two-stage approach of modelling spatial variation in species richness. Then, applying the model to data collected from eight avian communities in northern Italy, we evaluate how species richness varies in space as a function of habitat complexity. Key-words: Bayesian analysis, Biodiversity, Biogeography, Community structure, Data augmentation, Geographic variation, Site occupancy models, Species richness. This article is protected by copyright. All rights reserved.
We compiled all credible repeated lion surveys and present time series data for 47 lion (Panthera leo) populations. We used a Bayesian state space model to estimate growth rate-λ for each population and summed these into three regional sets to provide conservation-relevant estimates of trends since 1990. We found a striking geographical pattern: African lion populations are declining everywhere, except in four southern countries (Botswana, Namibia, South Africa, and Zimbabwe). Population models indicate a 67% chance that lions in West and Central Africa decline by one-half, while estimating a 37% chance that lions in East Africa also decline by one-half over two decades. We recommend separate regional assessments of the lion in the World Conservation Union (IUCN) Red List of Threatened Species: already recognized as critically endangered in West Africa, our analysis supports listing as regionally endangered in Central and East Africa and least concern in southern Africa. Almost all lion populations that historically exceeded ∼500 individuals are declining, but lion conservation is successful in southern Africa, in part because of the proliferation of reintroduced lions in small, fenced, intensively managed, and funded reserves. If management budgets for wild lands cannot keep pace with mounting levels of threat, the species may rely increasingly on these southern African areas and may no longer be a flagship species of the once vast natural ecosystems across the rest of the continent.
Distribution data form the basis of the study of zoo-geography, which has applications in, inter alia,
ecology and conservation. Written records were used to estimate the distribution patterns of some of the
medium- to large-sized terrestrial mammals in central, southern and western South Africa, and
neighbouring Lesotho, during the early historical period (late 1400 s to the 1920s). The sources of these
records comprise mainly published or unpublished letters, journals, diaries or books written by literate
pioneers – notably various missionaries, explorers, travellers, naturalists, military personnel, big game
hunters and agro-pastoralists. The classification (according to record type) of the written records in key
publications was standardised, and records overlooked by them are taken into account. Interpretation of
the spatial patterns provided by the written records was aided by reference to supporting information,
in the form of qualifying palaeontological, zoo-archaeological and museum records. Written records of
acceptable quality are shown, together with supporting records (where applicable), on a series of
species occurrence maps, which also depict the biomes that are represented in the study area. The
information on these maps is interpreted, together with relevant information in the source texts and a
map of the bioregions that constitute the biomes in question, to estimate distribution patterns that
prevailed during the period under study. Data are presented for 27 genera, 36 species and 2 subspecies,
comprising 7 carnivores and 30 herbivores. Despite the limitations associated with the use of written
records, the information provided is considered to offer a realistic distribution pattern for most of the
taxa covered. The use of supporting records is justified, since the majority of these corroborate the
ranges derived from the written records. The present study enhances our knowledge of distribution
patterns for these larger mammal species in a large part of the southern African sub-region during the
early historical period. It also provides a first attempt to describe the sub-regional scale, historical,
distribution patterns within the context of the broad biogeographical characteristics of the area in
question. There is a need to extend the coverage achieved by this study to include the remaining
approx. 30% of “South Africa”, i.e. the region incorporating South Africa, Lesotho and Swaziland, and
also the area incorporated by the countries of Namibia, Botswana, Zimbabwe and Mozambique. This
level of coverage will permit enhanced definition of historical distribution patterns for some larger
mammals in the southern African sub-region. There is also a need to better understand the drivers, as
well as the implications, of the observed changes in the distribution of the larger mammals since the
start of the historical period.
We conducted a meta-analysis of local hunting practices affecting the carnivores of forested Africa and Madagascar to collate the information available on this subject and to assess underlying trends in offtake rates. We located 62 relevant articles in a detailed literature search; the data included taxa reported as hunted, the purpose of hunting and the hunting method. The families most reported as hunted were Herpestidae and Viverridae (excluding Civettictis civetta), with 32.7 and 19.2% of total records, with C. civetta comprising 13.5% of records and Nandina binotata 9.9%. Hunting for consumption was the most commonly reported purpose (61.7% of all records). Sale for consumption was associated with 60.5% of all consumption records, and sale of any kind was reported for 56.6% of all records. The number of carnivore carcasses or parts sold at urban markets rose by 8.2% from the 1990s to the 2000s. The commonest hunting methods were traps (31.0% of records) and guns (16.6%). For records reporting the use of guns, 89.4% also reported sale of some kind. We conclude that carnivores are hunted pervasively across the forested regions of mainland Africa and Madagascar, and offtake rates for both personal use and income are probably increasing. These findings have implications for efforts to protect dwindling forest ecosystems and to establish sustainable consumptive practices.
Conservation resources are limited, making it impossible to invest equally in all threatened species. One way to maximise conservation gains is to focus upon those species with particular public appeal, using them to generate funding and support that could also benefit less charismatic species. Although this approach is already used by many conservation organisations, no reliable metrics currently exist to determine the likely charisma of a given species, and therefore identify the most appropriate targets for such campaigns. Here we use market research techniques on over 1500 people from five continents to assess the relative charisma of different mammals, which factors appear to drive it, and how these patterns vary between countries. Felids and primates emerged as highly favoured species for conservation, with the tiger (Panthera tigris) the top species by a wide margin. Using an information theoretic approach we develop models that successfully predict respondents’ preferences across the entire sample, suggesting global commonalities in the attributes that people prefer for conservation. However, by analysing each country separately we are able to improve our models, thus highlighting the importance of identifying locally specific flagships for conservation. The most important attributes were body size and IUCN status, although the extent of baldness, whether the species was a potential threat to humans and whether the eyes were forward or side facing were also widely important. Several of the key attributes revealed in this study could be extrapolated to nearly all terrestrial mammals, paving the way for a standardised global identification of species likely to prove effective for future conservation campaigns. The public preferred species with which they had affinity and familiarity, and we discuss how these aspects could be increased to promote the under-achievers, whilst maximising the funding potential of the highly charismatic mammals. While the felids are widely regarded as a popular taxonomic group, the great extent to which they appealed to our respondents emphasises their potential as ambassadors for conservation. Indeed, the big cats were so highly rated that we might think of them as one, Felis felicis: a globally powerful flagship for conservation.
We present the results of an experimental investigation on the crystallography of the dimpled patterns obtained through wrinkling of a curved elastic system. Our macroscopic samples comprise a thin hemispherical shell bound to an equally curved compliant substrate. Under compression, a crystalline pattern of dimples self-organizes on the surface of the shell. Stresses are relaxed by both out-of-surface buckling and the emergence of defects in the quasi-hexagonal pattern. Three-dimensional scanning is used to digitize the topography. Regarding the dimples as point-like packing units produces spherical Voronoi tessellations with cells that are polydisperse and distorted, away from their regular shapes. We analyze the structure of crystalline defects, as a function of system size. Disclinations are observed and, above a threshold value, dislocations proliferate rapidly with system size. Our samples exhibit striking similarities with other curved crystals of charged particles and colloids. Differences are also found and attributed to the far-from-equilibrium nature of our patterns due to the random and initially frozen material imperfections which act as nucleation points, the presence of a physical boundary which represents an additional source of stress, and the inability of dimples to rearrange during crystallization. Even if we do not have access to the exact form of the interdimple interaction, our experiments suggest a broader generality of previous results of curved crystallography and their robustness on the details of the interaction potential. Furthermore, our findings open the door to future studies on curved crystals far from equilibrium.
1.Hill numbers unify biodiversity metrics by combining several into one expression. For example, species richness, Shannon's diversity index, and the Gini-Simpson index are a few of the most used diversity measures, and they can be expressed as Hill numbers. Traditionally, Hill numbers have been calculated from relative abundance data but the expression has been modified to use incidence data as well. We demonstrate an approach for estimating Hill numbers using an occupancy modeling framework that accounts for imperfect detection.2.We alter the Hill numbers formula to use occupancy probabilities as opposed to the incidence probabilities that have been used previously, and to calculate its summations from the modeled species richness. After introducing the occupancy-based Hill numbers, we demonstrate the differences between them and the incidence-based Hill numbers previously used through a simulation study and two applications.3.In the simulation study and the two examples using real data, the occupancy-based Hill numbers were larger than the incidence-based Hill numbers, although species richness was estimated similarly using both methods.4.The occupancy-based Hill number estimators are always at their asymptotic values (i.e., as if an infinite number of samples have been taken for the study region), therefore making it easy to compare biodiversity between different assemblages. In addition, the Hill numbers are computed as derived quantities within a Bayesian hierarchical model, allowing for straightforward inference.This article is protected by copyright. All rights reserved.
1. Large carnivores are a critical component of Africa’s biodiversity, and their
conservation requires a clear understanding of interactions between large
carnivores and people.
2. By reviewing existing literature, we identify 14 key factors that influence large
African carnivore conservation, including ecological (biodiversity conservation,
interspecific competition, ranging behaviour, ecological resilience, prey availability,
livestock predation, disease and population viability), socio-economic (people’s
attitudes and behaviours and human costs and benefits of coexistence with
large carnivores) and political (conservation policy development and implementation,
conservation strategies and land use zoning) factors.
3. We present these key factors in a model illustrating the levels of impact on large
African carnivore conservation.
4. We identify the key principle that underpins each factor and its implications
for both large carnivore conservation and human–carnivore conflict.
5. We provide a synthesis of the key factors and related principles in large African
carnivore conservation and highlight the importance of the site-specific and
species-specific context in conservation policy and implementation, formulated
through an interdisciplinary and adaptive approach.
Given the budgetary restrictions on scientific research and the increasing need to better inform conservation actions, it is important to identify the patterns and causes of biases in research effort. We combine bibliometric information from a literature review of almost 16,500 peer-reviewed publications on a well-known group of 286 species, the Order Carnivora, with global datasets on species' life history and ecological traits to explore patterns in research effort. Our study explores how species' characteristics influenced the degree to which they were studied (measured as the number of publications). We identified a wide variation in intensity of research effort at both Family and Species levels, with some of the least studied being those which may need protection in future. Our findings hint at the complex role of human perspectives in setting research agendas. We found that better-studied species tended to be large-bodied and have a large geographic range whilst omnivory had a negative relationship with research effort. IUCN threat status did not exhibit a strong relationship with research effort which suggests that the conservation needs of individual species are not major drivers of research interest. This work is the first to use a combination of bibliometric analysis and biological data to quantify and interpret gaps in research knowledge across an entire Order. Our results could be combined with other resources, such as Biodiversity Action Plans, to prioritise and co-ordinate future research effort, whilst our methods can be applied across many scientific disciplines to describe knowledge gaps.
Predation and scavenging have been classically understood as independent processes, with predator–prey interactions and scavenger–carrion relationships occurring separately. However, the mere recognition that most predators also scavenge at variable rates, which has been traditionally ignored in food-web and community ecology, leads to a number of emergent interaction routes linking predation and scavenging. The general goal of this review is to draw attention to the main inter-specific interactions connecting predators (particularly, large mammalian carnivores), their live prey (mainly ungulates), vultures and carrion production in terrestrial assemblages of vertebrates. Overall, we report an intricate network of both direct (competition, facilitation) and indirect (hyperpredation, hypopredation) processes, and provide a conceptual framework for the future development of this promising topic in ecological, evolutionary and biodiversity conservation research. The classic view that scavenging does not affect the population dynamics of consumed organisms is questioned, as multiple indirect top-down effects emerge when considering carrion and its facultative consumption by predators as fundamental and dynamic components of food webs. Stimulating although challenging research opportunities arise from the study of the interactions among living and detrital or non-living resource pools in food webs.
Due to anthropogenic pressures, African lion (Panthera leo) populations in Kenya and Tanzania are increasingly limited to fragmented populations. Lions living on isolated habitat patches exist in a matrix of less-preferred habitat. A framework of habitat patches within a less-suitable matrix describes a metapopulation. Metapopulation analysis can provide insight into the dynamics of each population patch in reference to the system as a whole, and these analyses often guide conservation planning. We present the first metapopulation analysis of African lions. We use a spatially-realistic model to investigate how sex-biased dispersal abilities of lions affect patch occupancy and also examine whether human densities surrounding the remaining lion populations affect the metapopulation as a whole. Our results indicate that male lion dispersal ability strongly contributes to population connectivity while the lesser dispersal ability of females could be a limiting factor. When populations go extinct, recolonization will not occur if distances between patches exceed female dispersal ability or if females are not able to survive moving across the matrix. This has profound implications for the overall metapopulation; the female models showed an intrinsic extinction rate from five-fold to a hundred-fold higher than the male models. Patch isolation is a consideration for even the largest lion populations. As lion populations continue to decline and with local extinctions occurring, female dispersal ability and the proximity to the nearest lion population are serious considerations for the recolonization of individual populations and for broader conservation efforts.
Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around
the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest
mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large carnivores have substantial
effects on the structure and function of diverse ecosystems. Significant cascading trophic interactions, mediated by their
prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems. Unexpected
effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna
abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology;
and crop damage. Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately
determine the fate of Earth’s largest carnivores and all that depends upon them, including humans.
Intraguild predation (IGP) and interspecific killing (IK) have been recently acknowledged as important ecological forces that could influence community structure. Not only can carnivores influence prey community composition, they might also impact the populations of other carnivores. The goal of the current study was to assess the role of IGP and IK as significant forces influencing carnivoran assemblages in South America. To this end, we compiled the available records on 35 species of terrestrial carnivorans in the subcontinent, to investigate the potential and actual extent of IGP/IK as widespread ecological forces. We considered potential intraguild predators those having >20 % range overlap and body mass 2–5.4 times greater than that of other guild members and likely-potential intraguild predators those that, in addition, were also hypercarnivorous. The potential number of intraguild predators for those species evaluated ranged from zero to 18 (mean=5.35±SE 0.74). IGP/IK events (n =116) included 52 pairs of Neotropical carnivorans, 13 of which were killers and 25 were victims. Confirmed intraguild predator species (n =13) accounted for 37.1 % of the assemblage, nearly the same value predicted to be likely potential predators (n =14). IGP and IK were highly associated with the hypercarnivorous felids, whereas victim species were most often the omnivorous procyonids and skunks. The results indicate jaguars, pumas, and ocelots as the species most likely to have significant impact on the guild. IGP and IK are not random and reflect widespread interactions that influence carnivoran community structure in South America.
Managers of African lions (Panthera leo) on reserves where they have been reintroduced
increasingly face challenges associated with ecological regulation,genetic degradation and
increased susceptibility to catastrophic events. The Lion Management Forum (LiMF) was
formed in 2010 to define these challenges and explore possible solutions with the view to
developing appropriate management guidelines. LiMF bases its recommendations on the
ecologically sound premise thatmanagers should,as far as possible,mimic natural processes
that have broken down in reserves, using proactive rather than reactive methods, i.e.
management should focus on causal mechanisms as opposed to reacting to symptoms.
Specifically, efforts should be made to reduce population growth and thus reduce the number
of excess lions in the system; disease threats should be reduced through testing and vaccination
whenever animals are translocated; and genetic integrity should be monitored.
The latter is particularly important, as most of these reserves are relatively small (typically
<1000 km2). An adaptive management framework is needed to implement the guidelines
developed here on reserves across the country, with regional nodes addressing more local
genetic issues, within an overall national plan. Ongoing monitoring and scientific assessment
of behavioural, population and systemic responses of lion populations and responsive
modification of the guidelines, should improve management of lions on small reserves in
South Africa. This approach will provide a template for evidence-based conservation
management of other threatened species. Ultimately ‘National Norms and Standards’must
be established and a ‘National Action Plan’ for lions in South Africa developed.
Managers of reintroduced lion (Panthera leo) populations in small reserves (<1000 km2) in South Africa are challenged by high rates of population increase and how best to control them. We combined data from 14 small, fenced reserves to evaluate growth rate parameters and compared them to those in larger and/or open reserves. Growth rates of lions in small fenced reserves were only matched by those in Nairobi National Park (NP), which is relatively small and where the majority of the subadults emigrated away from the park. Initially, South African managers unconsciously mimicked this system by removing subadults to control population numbers, but increasingly chose euthanasia and hunting in the past decade, as the demand for wild lions for translocation decreased. They have, however, expressed a desire to use other methods of population control and mimic other open systems such as Kruger NP and Serengeti NP. Kruger NP had older ages of first reproduction and longer inter-birth intervals that could be mimicked through selective contraception. Alternatively, Serengeti NP had smaller litter sizes and lower cub survival, which could be mimicked through surgery to reduce litter sizes and, less attractively as it still involves lethal management and raises serious ethical concerns, selective culling of cubs. Mimicking Kruger NP may be more desirable as it is more ecologically similar to the small reserves than Serengeti NP. This understanding of the current situation, and how it could be altered to more closely mimic natural systems, will facilitate the development of a metapopulation-based management plan for lions in small reserves in South Africa.
Carnivore extinctions frequently have cascading impacts through an ecosystem, so effective management of ecological communities requires an understanding of carnivore vulnerability. This has been hindered by the elusive nature of many carnivores, as well as a disproportionate focus on large-bodied species and particular geographic regions. We use multiple survey methods and a hierarchical multi-species occupancy model accounting for imperfect detection to assess extinction risk across the entire carnivore community in Ghana’s Mole National Park, a poorly studied West African savanna ecosystem. Only 9 of 16 historically occurring carnivore species were detected in a camera-trap survey covering 253 stations deployed for 5469 trap days between October 2006 and January 2009, and our occupancy model indicated low overall likelihoods of false absence despite low per-survey probabilities of detection. Concurrent sign, call-in, and village surveys, as well as long-term law enforcement patrol records, provided more equivocal evidence of carnivore occurrence but supported the conclusion that many carnivores have declined and are likely functionally or fully extirpated from the park, including the top predator, lion (Panthera leo). Contrary to expectation, variation in carnivore persistence was not explained by ecological or life-history traits such as body size, home range size or fecundity, thus raising questions about the predictability of carnivore community disassembly. Our results imply an urgent need for new initiatives to better protect and restore West Africa’s embattled carnivore populations, and they highlight a broader need for more empirical study of the response of entire carnivore communities to anthropogenic impact.
Ecology has entered into a dynamic period, driven by both the urgency of large-scale ecological problems and startling new ecological findings that are being shared broadly beyond the scientific community. Both of these factors are well represented by observational approaches to ecology, which are re-emerging after a long period of deference to manipulative experimental approaches. These approaches examine ecological patterns and processes through data gathered in situations where nature has not been purposefully manipulated. The use of unmanipulated observational data reflects on the work of early naturalists, but is greatly enhanced by technological advances in remote sensing, microscopy, genetics, animal-borne sensors, and computing. Once dismissed as merely "exploratory", strictly observational approaches to ecology have demonstrated capability in testing hypotheses by correlating variables, comparing observed patterns to output from existing models, exploiting natural experiments, and simulating experiments within large datasets. These approaches can be used in a stand-alone fashion, but are strengthened when reconciled with experimental manipulations to isolate fine-scale ecological mechanisms.
Predation risk" and "fear" are concepts well established in animal behavior literature. We expand these concepts to develop the model of the "landscape of fear". The landscape of fear represents relative levels of predation risk as peaks and valleys that reflect the level of fear of predation a prey experiences in different parts of its area of use. We provide observations in support of this model regarding changes in predation risk with respect to habitat types, and terrain characteristics. We postulate that animals have the ability to learn and can respond to differing levels of predation risk. We propose that the landscape of fear can be quantified with the use of well documented existing methods such as giving-up densities, vigilance observations, and foraging surveys of plants. We conclude that the landscape of fear is a useful visual model and has the potential to become a unifying ecological concept.
The ‘Big Five’ charismatic megafauna concept is considered key for financial competitiveness of protected areas in South Africa. However, this Western colonial concept is also leading to an underappreciation of wider biodiversity and the recovery of other endangered species. This study assessed the heterogeneity of tourist preferences for big game species in KwaZulu-Natal, South Africa, using a choice experiment approach, employing latent class modelling, in order to identify tourists' segments not necessarily drawn to the Big Five. The latent class segmentation identified two segments for both international and national tourists, largely defined by socio-economic characteristics. Less experienced and wealthier tourists were mostly interested in charismatic megafauna, while more experienced, but lower income tourists showed preferences for a broader range of species. Exploring viewing preferences in this way illustrates the potential to realign conservation businesses to achieve biodiversity conservation objectives. In the short term, managing protected areas for the Big Five and other favourite species will continue to deliver significant financial benefits to local stakeholders, but policy makers should consider using financial mechanisms to subsidize conservation actions for less charismatic species and develop the biodiversity base of safari tourism in South Africa.
Conservation efforts in South Africa play out across multi‐use landscapes where formal protected areas coexist with private wildlife business (ecotourism and/or hunting) in a human‐dominated matrix. Despite the persistence of highly diverse carnivore guilds, management idiosyncrasies are often orientated towards charismatic large predators and assemblage‐level patterns remain largely unexplored. We conducted an extensive camera‐trap survey in a natural quasi‐experimental setting in KwaZulu‐Natal, South Africa. We sampled across a protection gradient characterized by a provincial protected area (highest and formal protection status), a private ecotourism reserve, game ranches and traditional communal areas (lowest protected status). We evaluated assemblage‐level and species‐specific responses of free‐ranging carnivores to the varying management contexts and associated environmental gradients. Despite similar assemblage composition between management contexts, site‐scale carnivore richness and occupancy rates were greater in the formal protected area than adjacent private reserve and game ranches. Carnivore occupancy was more similar between these private wildlife areas, although putative problem species were more common in the private reserve, and contrasted with depauperate assemblages in least protected communal lands. Variation in carnivore occupancy probabilities was largely driven by land use contexts, that is, the level and nature of protection, relative to underlying fine‐scale landscape attributes (e.g. distance to conservation fences) or apex predator populations. Synthesis and applications. Our findings provide convincing empirical support for the added value of multi‐tenure conservation estates augmenting and connecting South Africa's protected areas. However, our emphasis on free‐ranging carnivores exemplifies the importance of maintaining areas under long‐term formal protection and the risks with viewing lucrative wildlife business as a conservation panacea. We suggest that unmanaged carnivore species be the formal components of carnivore reintroduction and recovery programmes to better gauge the complementary conservation role of South Africa's private land. Our findings provide convincing empirical support for the added value of multi‐tenure conservation estates augmenting and connecting South Africa's protected areas. However, our emphasis on free‐ranging carnivores exemplifies the importance of maintaining areas under long‐term formal protection and the risks with viewing lucrative wildlife business as a conservation panacea. We suggest that unmanaged carnivore species be the formal components of carnivore reintroduction and recovery programmes to better gauge the complementary conservation role of South Africa's private land.
The bush-meat poaching crisis is a significant threat to biodiversity in tropical forest and savannah biomes, however its impacts on wild animal populations are often difficult to quantify across large spatial scales. Using data from 17 camera trap survey sites in southern Africa, within the Kavango-Zambezi (KAZA) Transfrontier Conservation Area, we show it is possible to assess the demographic impact of wire-snare bush-meat poaching on large carnivore populations, distribution of snaring hotspots and drivers of bush-meat poaching prevalence across this landscape. Results suggest that mortalities in snares may have significant demographic effects on lions (Panthera leo) and spotted hyaenas (Crocuta crocuta) with evidence for population declines and extirpation of large carnivores in the most heavily affected areas. Spatial drivers of bush-meat poaching were found to be a composite of anthropogenic threat scores, environmental resource extraction, protected area size and land-use type. Incidences of snared large carnivores were more prevalent in trophy hunting areas than national parks. Across our study sites, bush-meat poaching has the potential to cause severe declines in populations of large carnivores, particularly in small isolated protected areas surrounded by areas of high human population growth, with resulting loss of regional connectivity and increasing fragmentation of the KAZA landscape.
The role that apex predators play in ecosystem functioning, disease regulation and biodiversity maintenance is increasingly debated. However, the positive impacts of their presence in terrestrial ecosystems, particularly in human-dominated landscapes, remain controversial. Limited experimental insights regarding the consequences of apex predator recoveries may be behind such controversy and may also impact on the social acceptability towards the recovery of these species. Using a quasi-experimental design and state-of-the-art density estimates, we show that mesopredator abundances were reduced after the restoration of an apex predator, with evidence of resonating positive impacts on lower trophic levels. Iberian lynx Lynx pardinus reintroduction was followed by the reduction of the abundance of mesocarnivores (red foxes Vulpes vulpes and Egyptian mongooses Herpestes ichneumon by ca. 80%) and the recovery of small game of high socioeconomic value (European rabbits Oryctolagus cuniculus and red-legged partridges Alectoris rufa). The observed mesopredator reduction resulted in an estimated 55.6% less rabbit consumption for the entire carnivore guild. Our findings have important implications for the social acceptability of Iberian lynx reintroductions, which crucially depend on the perception of private land owners and managers. Under certain circumstances, restoring apex predators may provide a sustainable and ethically acceptable way to reduce mesopredator abundances.
Predation is a fundamental force exerting strong selective pressure on prey populations. Predators not only kill prey, triggering lethal effects, but also hunt prey which can induce risk effects. Foundational research has documented the importance of risk effects in predator-prey systems of arthropods, fish, birds, and rodents, among others. Risk effects research in carnivore-ungulate systems has expanded in the last 20 years. Presently, the degree to which this research mirrors the complexity of carnivore-ungulate trophic systems has been questioned. We synthesized this literature to quantify the tendency of risk effects research in carnivore-ungulate systems to be multispecies in design. Among the 170 studies that we reviewed, we found that on average just 1.26 (range = 1 to 5) carnivore species and 1.60 (range = 1 to 11) ungulate species were considered per study. Furthermore, 63% (n = 107 of 170) of the studies featured single predator - single prey research designs. These results contrast with the fact that all but one of the 82 carnivore-ungulate systems used this literature had multiple species of carnivores and/or ungulates. Thus, we detected a tendency to simplify complex systems. We relate these observations to the role of simplicity as: i) an underlying value of science (i.e., Occam's razor), ii) a cornerstone of predator-prey theory (e.g., Lotka-Volterra equations), and iii) part of the origins of risk effects research (i.e., experimental systems). Finally, we ground our discussion in the implications of this research for the conservation of carnivores and ungulates in the dynamic 21st century.
Predators and scavengers are frequently persecuted for their negative effects on property, livestock and human life. Research has shown that these species play important regulatory roles in intact ecosystems including regulating herbivore and mesopredator populations that in turn affect floral, soil and hydrological systems. Yet predators and scavengers receive surprisingly little recognition for their benefits to humans in the landscapes they share. We review these benefits, highlighting the most recent studies that have documented their positive effects across a range of environments. Indeed, the benefits of predators and scavengers can be far reaching, affecting human health and well-being through disease mitigation, agricultural production and waste-disposal services. As many predators and scavengers are in a state of rapid decline, we argue that researchers must work in concert with the media, managers and policymakers to highlight benefits of these species and the need to ensure their long-term conservation. Furthermore, instead of assessing the costs of predators and scavengers only in economic terms, it is critical to recognize their beneficial contributions to human health and well-being. Given the ever-expanding human footprint, it is essential that we construct conservation solutions that allow a wide variety of species to persist in shared landscapes. Identifying, evaluating and communicating the benefits provided by species that are often considered problem animals is an important step for establishing tolerance in these shared spaces.
Africa is endowed with a diverse guild of small carnivores, which could benefit stakeholders by providing ecosystem services while fostering conservation tolerance for carnivores. To investigate the potential of small carnivores for the biological control of rodents within agro-ecosystems, we assessed both the eco- logical and social landscapes within two rural villages in the Vhembe Biosphere Reserve, South Africa. We employed a camera trapping survey underpinned by an occupancy modelling framework to distinguish between ecological and observation processes affecting small carnivore occupancy. We also used ques- tionnaires to investigate perceptions of small carnivores and their role in pest control. We found the greatest diversity of small carnivores in land used for cropping in comparison to grazing or settlements. Probability of use by small carnivores was influenced negatively by the relative abundance of domestic dogs and positively by the relative abundance of livestock. Greater carnivore diversity and probability of use could be mediated through habitat heterogeneity, food abundance, or reduced competition from domestic carnivores. Village residents failed to appreciate the role of small carnivores in rodent control. Our results suggest that there is significant, although undervalued, potential for small carnivores to pro- vide ecosystem services in agro-ecosystems.
Competition can have profound impacts on the structure and function of ecological communities. Despite this, the population-level effects of intraguild competition on large carnivores remain largely unknown, due to a paucity of long-term studies that focus simultaneously on competing species. Here, we comprehensively examine competitive interactions, including their demographic consequences , between 2 top predators, lions Panthera leo and leopards P. pardus. We tested the hypothesis that lions, as the dominant competitor, limit the distribution and abundance of leopards, using dietary, spatial, and life-history data collected concurrently on the 2 species. Dietary overlap between lions and leopards was limited, with lions targeting large-to very large-sized prey and leopards small-to medium-sized prey. Leopards did not actively avoid lions, either predictively or reactively, except in riparian woodland where the likelihood of encountering lions was highest. Lions accounted for more than 20% of leopard mortality, but this appeared to be compensatory. Observed and modeled population growth was similar between the 2 species, with both exhibiting net emigration. Our findings suggest that lions do not suppress leopard populations or limit their distribution, at least in our study area. Adequate availability of suitably-sized prey apparently enabled resource partitioning between lions and leopards, facilitating their coexistence. The potential for competition increases in areas devoid of large prey and should be considered in recovery efforts for the 2 species. Our study provides novel empirical evidence that intraguild competition does not always have population-level consequences for subordinates, even if they suffer from strong inference competition with dominant competitors.
Ecologists are increasingly looking at how richness of traits — rather than number of species — helps set the health of ecosystems.
Carnivores are among the mammal species most frequently used in traditional folk medicine around the world. Therefore, this chapter assesses the global use of carnivores in traditional folk medicine and its implications. Our review indicated that at least 108 species of carnivores are used in traditional medicine worldwide. Of the species in medicinal use, 14 are classified as Near Threatened, 18 species as Vulnerable, 9 species as Endangered, and one as Critically Endangered on the IUCN Red List. For some species, medicinal use represents an additional direct pressure that may have contributed to declines in natural populations. In addition, the use of medicinal animals may have indirect impacts on the conservation of other species through the spread of disease. To minimize both harvest impact and disease spread, guidance on use of medicinal species may be useful. This could include an exploration of the use of alternatives and implementation of quality measures. © 2013 Springer-Verlag Berlin Heidelberg. All rights are reserved.
In most mathematical models of population dynamics in ecological communities, the death rate of prey species is a linearly increasing function of the density of their predator(s). If antipredator behavior is incorporated into such models it becomes very unlikely that prey death rate is a linear function of predator density. Also, it is possible for the prey death rate to decrease, rather than increase, as a function of the population density of its predator. Decreasing predation rates may be common when the prey organism is attempting to accumulate resources for growth or reproduction. Decreasing predation rates are less likely when the prey organism is attempting to minimize mortality. These results and earlier ones on indirect effects generated by optimal foraging suggest that higher order interactions should be extremely common in natural communities. -Author
Camera trap surveys exclusively targeting features of the landscape that increase the probability of photographing one or several focal species are commonly used to draw inferences on the richness, composition and structure of entire mammal communities. However, these studies ignore expected biases in species detection arising from sampling only a limited set of potential habitat features. In this study, we test the influence of camera trap placement strategy on community-level inferences by carrying out two spatially and temporally concurrent surveys of medium to large terrestrial mammal species within Tanzania's Ruaha National Park, employing either strictly game trail-based or strictly random camera placements. We compared the richness, composition and structure of the two observed communities, and evaluated what makes a species significantly more likely to be caught at trail placements. Observed communities differed marginally in their richness and composition , although differences were more noticeable during the wet season and for low levels of sampling effort. Lognormal models provided the best fit to rank abundance distributions describing the structure of all observed communities, regardless of survey type or season. Despite this, carnivore species were more likely to be detected at trail placements relative to random ones during the dry season, as were larger bodied species during the wet season. Our findings suggest that, given adequate sampling effort (> 1400 camera trap nights), placement strategy is unlikely to affect inferences made at the community level. However, surveys should consider more carefully their choice of placement strategy when targeting specific taxonomic or trophic groups.
Communities are comprised of individual species that respond to changes in their environment depending in part on their niche requirements. These species comprise the biodiversity of any given community. Common biodiversity metrics such as richness, evenness, and the species abundance distribution are frequently used to describe biodiversity across ecosystems and taxonomic groups. While it is increasingly clear that researchers will need to forecast changes in biodiversity, ecology currently lacks a framework for understanding the natural background variability in biodiversity or how biodiversity patterns will respond to environmental change. We predict that while species populations depend on local ecological mechanisms (e.g., niche processes) and should respond strongly to disturbance, community-level properties that emerge from these species should generally be less sensitive to disturbance because they depend on regional mechanisms (e.g., compensatory dynamics). Using published data from terrestrial animal communities, we show that community-level properties were generally resilient under a suite of artificial and natural manipulations. In contrast, species responded readily to manipulation. Our results suggest that community-level measures are poor indicators of change, perhaps because many systems display strong compensatory dynamics maintaining community-level properties. We suggest that ecologists consider using multiple metrics that measure composition and structure in biodiversity response studies.
Top-down processes, via the direct and indirect effects of interspecific competitive killing (no consumption of the kill) or intraguild predation (consumption of the kill), can potentially influence the spatial distribution of terrestrial predators, but few studies have demonstrated the phenomenon at a continental scale. For example, in North America, grey wolves (Canis lupus) are known to kill coyotes (Canis latrans), and coyotes, in turn, may kill foxes (Vulpes spp.), but the spatial effects of these competitive interactions at large scales are unknown. Here, we analyse fur return data across eight jurisdictions in North America to test whether the presence or absence of wolves has caused a continent-wide shift in coyote and red fox (Vulpes vulpes) density. Our results support the existence of a continental scale cascade whereby coyotes outnumber red foxes in areas where wolves have been extirpated by humans, whereas red foxes outnumber coyotes in areas where wolves are present. However, for a distance of up to 200 km on the edge of wolf distribution, there is a transition zone where the effects of top-down control are weakened, possibly due to the rapid dispersal and reinvasion capabilities of coyotes into areas where wolves are sporadically distributed or at low densities. Our results have implications for understanding how the restoration of wolf populations across North America could potentially affect co-occurring predators and prey. We conclude that large carnivores may need to occupy large continuous areas to facilitate among-carnivore cascades and that studies of small areas may not be indicative of the effects of top-down mesopredator control. This article is protected by copyright. All rights reserved.
Most ecosystems have multiple predator species that not only compete for shared prey, but also pose direct threats to each other. These intraguild interactions are key drivers of carnivore community structure, with ecosystem-wide cascading effects. Yet, behavioral mechanisms for coexistence of multiple carnivore species remain poorly understood. The challenges of studying large, free-ranging carnivores have resulted in mainly coarse-scale examination of behavioral strategies without information about all interacting competitors. We overcame some of these challenges by examining the concurrent fine-scale movement decisions of almost all individuals of four large mammalian carnivore species in a closed terrestrial system. We found that the intensity ofintraguild interactions did not follow a simple hierarchical allometric pattern, because spatial and behavioral tactics of subordinate species changed with threat and resource levels across seasons. Lions (Panthera leo) were generally unrestricted and anchored themselves in areas rich in not only their principal prey, but also, during periods of resource limitation (dry season), rich in the main prey for other carnivores. Because of this, the greatest cost (potential intraguild predation) for subordinate carnivores was spatially coupled with the highest potential benefit of resource acquisition (prey-rich areas), especially in the dry season. Leopard (P. pardus) and cheetah (Acinonyx jubatus) overlapped with the home range of lions but minimized their risk using fine-scaled avoidance behaviors and restricted resource acquisition tactics. The cost of intraguild competition was most apparent for cheetahs, especially during the wet season, as areas with energetically rewarding large prey (wildebeest) were avoided when they overlapped highly with the activity areas of lions. Contrary to expectation, the smallest species (African wild dog, Lycaon pictus) did not avoid only lions, but also used multiple tactics to minimize encountering all other competitors. Intraguild competition thus forced wild dogs into areas with the lowest resource availability year round. Coexistence of multiple carnivore species has typically been explained by dietary niche separation, but our multi-scaled movement results suggest that differences in resource acquisition may instead be a consequence of avoiding intraguild competition. We generate a more realistic representation of hierarchical behavioral interactions that may ultimately drive spatially explicit trophic structures of multi-predator communities.
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Risks of predation or interference competition are major factors shaping the distribution of species. An animal's response to risk can either be reactive, to an immediate risk, or predictive, based on preceding risk or past experiences. The manner in which animals respond to risk is key in understanding avoidance, and hence coexistence, between interacting species. We investigated whether cheetahs (Acinonyx jubatus), known to be affected by predation and competition by lions (Panthera leo) and spotted hyaenas (Crocuta crocuta), respond reactively or predictively to the risks posed by these larger carnivores. We used simultaneous spatial data from Global Positioning System (GPS) radiocollars deployed on all known social groups of cheetahs, lions and spotted hyaenas within a 2700 km(2) study area on the periphery of the Okavango Delta in northern Botswana. The response to risk of encountering lions and spotted hyaenas was explored on three levels: short-term or immediate risk, calculated as the distance to the nearest (contemporaneous) lion or spotted hyaena, long-term risk, calculated as the likelihood of encountering lions and spotted hyaenas based on their cumulative distributions over a 6-month period and habitat-associated risk, quantified by the habitat used by each of the three species. We showed that space and habitat use by cheetahs was similar to that of lions and, to a lesser extent, spotted hyaenas. However, cheetahs avoided immediate risks by positioning themselves further from lions and spotted hyaenas than predicted by a random distribution. Our results suggest that cheetah spatial distribution is a hierarchical process, first driven by resource acquisition and thereafter fine-tuned by predator avoidance; thus suggesting a reactive, rather than a predictive, response to risk.