When pork is not on the menu: Assessing trophic competition between large carnivores and poachers
Introduction
Overexploitation of wildlife for meat is a widespread phenomenon, which drives populations of many species toward extinction (Milner-Gulland et al., 2002). This pattern in form of pursuit hunting or trapping is known to also affect natural food webs (Rowcliffe et al., 2003) as species targeted by humans may play important roles in the diet of large carnivores (Henschel et al., 2011). A recent study revealed that humans exploit shared prey at 1.9 times higher rates than all other predators combined within the human-predator-prey communities studied (Darimont et al., 2015). Therefore, human hunters may compete with carnivores over food resources, acting as an unsustainable “super predator” (Darimont et al., 2015).
Large carnivores are especially vulnerable to low density and biomass of their preferred prey (Carbone et al., 2011) and prey depletion is one of their major threats worldwide (Wolf and Ripple, 2016). When prey is scarce, large carnivores may expand their hunting effort by increasing home ranges or changing activity patterns (Schmidt, 2008). However, if competition reaches exploitative levels, switching to other prey species or extermination from habitats may be observed (Henschel et al., 2011, Rosenblatt et al., 2016). Additionally, prey depletion may force carnivores, such as big cats, to shift toward livestock depredation and trigger retaliatory persecution by humans (Khorozyan et al., 2015). Therefore, prey depletion is a vitally important factor for the survival of large carnivores, which requires further attention by conservationists (Chapron et al., 2008).
Dietary competition between different carnivores is well-studied in ecology (see Caro and Stoner, 2003). Within the large carnivore guilds, species exploit different resources if sufficient prey is available or compete when prey is limited (Karanth and Sunquist, 2000, Odden et al., 2010, Harihar et al., 2011, Jumabay-Uulu et al., 2014). The degree of dietary niche overlap may indicate exploitative competition among predators (Caro and Stoner, 2003). However, the role of humans as an apex predator in the trophic niche of animal predators has been rarely studied (Henschel et al., 2011, Darimont et al., 2015, Foster et al., 2016). Conservation of large carnivores in a changing world requires ‘coexistence’ of human and animal predators, and understanding differences in their ecological niche in local context is increasingly necessary (Chapron and López-Bao, 2016).
All these aspects are relevant to preservation of big cats, such as the globally endangered Persian leopard (Panthera pardus saxicolor). The largest protected population of this felid (23–42 individuals) is known to exist in Golestan National Park (GNP), Iran (Hamidi et al., 2014). The main threat to leopards in GNP is thought to be road kills (Kiabi et al., 2002). However, the rapid population decline of at least three ungulate species in GNP since the 1970s may indicate that poaching of prey species is another important threat (Ghoddousi et al. in press). Such hunting pressure is targeted on ungulates, but not on leopards (Ghoddousi et al., 2016a). Understanding responses of leopards to declining prey species may help develop appropriate conservation measures for this endangered large carnivore (Lovari et al., 2013). In this study, we quantified the dietary niche overlap of leopard and poachers to assess the threat of prey depletion to leopard. We hypothesize that given high ungulate poaching rate in GNP (Ghoddousi et al. in press), prey depletion may threaten the survival of leopards in case of high dietary niche overlap between leopards and poachers.
Section snippets
Study area
GNP is located in northeastern Iran covering an area of 874 km2 (Fig. 1). Elevation ranges from 450 to 2411 m above sea level and precipitation from 866 to 142 mm from west to east, respectively, creating a variety of different habitats (Akhani, 2005). The park has a mountainous terrain covered by sub-humid Hyrcanian forests in the west, and steppes and semi-deserts to the east (Akhani, 2005). GNP is the oldest national park of Iran, established in 1957, and a UNESCO Biosphere Reserve. GNP is home
Leopard diet analysis
We collected 77 leopard scats containing 12 prey species (Fig. 2). The corrected proportions of prey individuals consumed showed the main contribution of wild boar (66.67%), followed by bezoar goat (18.14%), urial (13.24%) and red deer (1.97%) (Table 1).
Poacher seizure
We collected data on 75 cases of poacher seizures in GNP, reporting on 113 killed animals of eight species (Fig. 2). The corrected proportion of hunted species by poachers was highest for urial (68.75%), followed by red deer (13.54%), bezoar
Discussion
In this study, we documented hunting specialization of both the Persian leopard and local poachers in Golestan National Park. According to our results, dietary niche overlap of leopards and poachers is low, which suggests no exploitative competition between these two apex predators. Such pattern is likely due to the role of wild boar, which constitutes the major prey of leopard in the national park, but is widely avoided by poachers (Fig. 4). Due to the prohibition of pork consumption by Islam,
Conclusions
Conservation of threatened carnivores requires careful consideration of their dietary requirements and solutions to alleviate depletion of their prey (Wolf and Ripple, 2016). In this study, leopard and poachers showed exclusivity in their dietary/hunting niches in Golestan National Park despite rampant ungulate poaching. This is likely due to the major role of wild boar in leopard diet, which is not preferred by leopard nor extensively hunted by poachers due to religious beliefs. Considering
Acknowledgements
Iranian Department of Environment, Golestan provincial office of Department of Environment and administration of Golestan National Park provided permits for this study. We would like to thank Persian Wildlife Heritage Foundation for sharing their camera trapping and social survey data, as well as logistical support. Our gratitude goes to all rangers, local guides and volunteers who participated in this research. German Academic Exchange Service (DAAD) (project no. 91540556) and Panthera's
References (59)
- et al.
Feeding habitat selection by hunting leopards Panthera pardus in a woodland savanna: prey catchability versus abundance
Anim. Behav.
(2007) - et al.
The potential for interspecific competition among African carnivores
Biol. Conserv.
(2003) - et al.
Co-adaptation is key to coexisting with large carnivores
Trends Ecol. Evol.
(2016) - et al.
Coexistence with large carnivores informed by community ecology
Trends Ecol. Evol.
(2016) - et al.
Big cats kill more livestock when wild prey reaches a minimum threshold
Biol. Conserv.
(2015) - et al.
Meat tradition. The co-evolution of humans and meat
Appetite
(2015) - et al.
Spatial distribution drivers of Amur leopard density in northeast China
Biol. Conserv.
(2015) The Illustrated Flora of Golestan National Park, Iran
(2005)2nd Phase of Conservation of Leopard Project in Golestan National Park; Social Research
(2014)- et al.
Role of local culture, religion and human attitudes in the conservation of sacred populations of a threatened ‘pest’ species
Biodivers. Conserv.
(2014)
Conservation: the world's religions can help
Nature
The relationship between religion and attitudes toward large carnivores in northern India?
Hum. Dimens. Wildl.
Introduction to Distance Sampling Estimating Abundance of Biological Populations
The bigger they come, the harder they fall: body size and prey abundance influence predator-prey ratios
Biol. Lett.
The impact on tigers of poaching versus prey depletion
J. Appl. Ecol.
An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores
PLoS One
Random versus game trail-based camera trap placement strategy for monitoring terrestrial mammal communities
PLoS One
The unique ecology of human predators
Science
Wild meat: a shared resource amongst people and predators
Oryx
Evaluating prey switching in wolf on ungulate systems
Ecol. Appl.
Measuring and monitoring illegal use of natural resources
Conserv. Biol.
Effects of ranger stations on predator and prey distribution and abundance in an Iranian steppe landscape
Anim. Conserv.
Assessing the role of livestock in big cat prey choice using spatiotemporal availability patterns
PLoS One
Camera trap study of Persian leopard in Golestan National Park, Iran
Cat News
Responses of leopard Panthera pardus to the recovery of a tiger Panthera tigris population
J. Appl. Ecol.
Prey preferences and dietary overlap amongst Africa's large predators
S. Afr. J. Wildl. Res.
Prey preferences of the leopard (Panthera pardus)
J. Zool. (London)
Leopard prey choice in the Congo Basin rainforest suggests exploitative competition with human bushmeat hunters
J. Zool. (London)
Cited by (25)
Competition versus opportunism: Diet and trophic niche relationship of two sympatric apex carnivores in a tropical forest
2023, Acta Ecologica SinicaCitation Excerpt :In Southwest Primorskii Krai, Russia, the wild pig was one of the important prey for both predators, where Amur tigers preyed on adult individuals and Amur leopards primarily preyed on smaller, sub-adult individuals [58]. Our result is similar to study in Golestan National Park, Iran and which showed that wild pig was the most dominant prey in the diet of leopard due to the high numbers of that prey species in their study area [59]. Common langur was another second dominant prey species in the diet of leopards due to its greater arboreality and crypticity [16].
A security game approach for strategic conservation against poaching considering food web complexities
2021, Ecological ComplexityCitation Excerpt :Therefore, identifying predator-prey relationship provides the knowledge necessary to detect the consequences of poaching across food webs ‒ an issue which is rarely considered (Darimont et al., 2015; Rowcliffe et al., 2003). Moreover, researchers argue that the various dynamic interactions due to species overexploitation should be assessed, instead of relying on a simple assessment of predator and prey populations (Ghoddousi et al., 2017). In the context of the mathematical modeling of multi-species conservation against hunting, Rowcliffe et al. (2003) used mathematical simulation to model the impacts of human hunting on multi-species prey communities, predicting the effect of hunting on prey populations.
Prey availability modulates predicted range contraction of two large felids in response to changing climate
2021, Biological ConservationCitation Excerpt :Second, we assumed that the density of the four main prey species in the landscape would remain stable in the future. The prey species of leopard and cheetah in Iran are under poaching pressure and despite some recent local population recovery, their populations have dramatically declined inside and outside of conservation areas, with negative impacts on large carnivore populations (Ghoddousi et al., 2019; Ghoddousi et al., 2017). Therefore, we should interpret the predicted distribution range of prey species as an optimistic scenario, as we do not know how poaching may affect the future abundance of these species and how fast these species will be able to adapt to the new climatic conditions and move into the suitable habitats under future climate conditions.
The effects of aridity on land use, biodiversity and dietary breadth in leopards
2019, Mammalian BiologyCitation Excerpt :Together these opposing impacts might mean that leopard densities are similar in both arid and mesic regions of their distribution in the Western Cape but leopard diet is predicted to be much broader in the arid region where the land use (pastoralism and game farming) is predicted to support more biodiversity than croplands. Theoretically, greater prey diversity should allow for greater stability in a predator population (Petchey, 2000) as carnivores with a more diverse prey base can exhibit prey switching, allowing them to survive declines of key prey species (Ghoddousi et al., 2017). Reduction in the diversity of leopard prey can contribute to declines in population density (Harihar et al., 2011).
Crop variety and prey richness affect spatial patterns of human-wildlife conflicts in Iran's Hyrcanian forests
2018, Journal for Nature ConservationCitation Excerpt :We could verify some of the reported wild boar conflicts by visual observations of heavily eroded crops, e.a. rice and watermelon. The frequency of wild boar conflicts is linked to high abundance of this species in the Hyrcanian forests, which may be due to religious beliefs resulting in low poaching pressure on wild boar in Iran (Ghoddousi, Soofi, Amirhossein, Lumetsberger et al., 2017). Wild boars can be tolerant to human activities as they typically roam along the edges of habitats, consume and trample crops, and have a broad diet, including rice, wheat, sorghum, potatoes, beetroots, maize, beans and barley (Pandey et al., 2016; Schley & Roper, 2003).
- 1
Present address: Conservation Biogeography Lab, Geography Department, Humboldt-Universität zu Berlin, Germany.
- 2
Present address: TRAFFIC International, UK.
- 3
Present address: Raddepaw Foundation for Rural Development and Biodiversity Conservation, Iran.