Article

Compensatory life history responses of a mesopredator may undermine carnivore management efforts

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Abstract

Lethal carnivore management, aimed at reducing carnivore impacts, is a global phenomenon threatening the persistence of many carnivores. Black-backed jackals Canis mesomelas, the dominant cause of livestock predation in southern Africa, are widely hunted to reduce livestock predation. Despite centuries of lethal management, jackals persist. Smaller canids, like jackals, are highly adaptable and display variable responses to mortality sources, which may affect management outcomes. The effects of killing carnivores will depend on their behaviour, social organization, reproduction and dispersal patterns. We predicted that hunted jackals will alter demographic and reproductive patterns to compensate for increased mortality. Here, we collected demographic and reproductive information from harvested jackals and compared it between continually hunted (farms) and unmanaged populations (reserves). The removal of jackals from farms results in a decrease in median age from 5-6 years (reserves) to 2-3 years (farms). Hunting also changed the age structure of jackal populations from a stable population to an expanding population. This may be ascribed to the compensatory immigration of individuals from neighbouring unmanaged areas, suggesting the formation of a source-sink system. Unmanaged areas may act as source populations exporting young, dispersing individuals to hunted areas which may act as sinks. This is likely driven by disruptions in the normal, mutually exclusive territorial system resulting in low densities of conspecifics on farms. The low density of conspecifics allows younger individuals that would be socially precluded from reproducing to reproduce. Jackals on farms compensated for increased mortality by increasing the pregnancy rate of young individuals and increasing the litter size at younger ages, thereby increasing reproductive output. Synthesis and applications. The lethal management of predators is the prevailing strategy to reduce livestock predation. However, the highly adaptable nature of jackals and the combination of compensatory mechanisms such as increased reproduction and potential for immigration allow these predators to persist in the face of severe anthropogenic mortality, possibly through the formation of a source-sink system. These compensatory processes will continue to counter population management actions as long as recruitment from unmanaged areas persists.

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... There is some support for this hypothesis in that scavenging opportunities from large ungulates killed by cheetahs (Acinonyx jubatus) were the predominant food source for black-backed jackals in the Samara game reserve (near Graaf Reinet in the Great Karoo, Eastern Cape) and this did not vary across seasons. However, Brassine & Parker (2012) found that black- 11 Minnie et al. (2016) found from a study of culled black-backed jackals in the Eastern Cape that breeding females were better nourished than non-breeding females suggesting that the dynamic behind this increase in population is likely to have been the provision of food, rather than immigration into this fenced reserve. Similar results have been found for coyotes (Canis latrans) in the United States with the onset of reproduction and successful rearing of pups being positively linked to nutritional status (Knowlton et al., 1999: 400;Sachs, 2005;Gese, 2005). ...
... Studies of placental scarring reveal that litter size for black-backed jackals varies from one to eight pups with a mean of about four (Bothma, 1971a;Bingham and Purchase, 2002). Litter size amongst coyotes has been strongly correlated to food availability (Gese, 2005: 281) and this is probably also the case for blackbacked jackals (Moehlman, 1979(Moehlman, , 1987Minnie et al., 2016). ...
... The adaptability of black-backed jackals to local conditions makes them very challenging to study. For example, a study of black-backed jackals killed by culling operations in national parks in the Karoo and the Eastern Cape and on surrounding farmlands (Minnie et al., 2016) found that culled black-backed jackals were younger on the farms. This coupled with the fact that these younger jackals had a lower age of first pregnancy and larger litter sizes, led the authors to conclude that it was consistent with 'source-sink' dynamics (dispersal into farmlands). ...
... South African farmers' perception is that predator numbers are increasing (Avenant and Du Plessis 2008, Du Plessis 2013. Factors causing the possible increase in predator numbers include poor fencing, limited human presence, and the possibility that continuous predator removal operations over large parts in South Africa, especially over the last three decades, has led to compensatory immigration and breeding (Avenant and Du Plessis 2008, Minnie et al. 2016, 2018b. These perceptions are in accord with the decline in government support for commercial sheep farmers, including for fencing and predator control operations (Bergman et al. 2013, Natrass and Conradie 2018; the expansion of protected areas; the increase in game; weekend and hobby farms (Reed andKleynhans 2009, Du Plessis 2013); and an increase in farmer unemployment (Western Cape Department of Agriculture 2017). ...
... Many producers believe that mesocarnivores have to decrease drastically to reduce depredation to acceptable levels (Du Plessis et al. 2015). However, livestock predation by mesocarnivores is rooted in their ethological and ecological plasticity, which allows them to persist despite centuries of population reduction efforts (Bergman et al. 2013, Minnie et al. 2016, 2018a. ...
... Caracal and black-backed jackal occur throughout South Africa (Avenant et al. 2016, Minnie et al. 2016. They are the most important native predators that cause livestock losses (Blaum et al. 2009, Strauss 2009, Van Niekerk 2010, Thorn et al. 2012, Bergman et al. 2013, Badenhorst 2014, Kerley et al. 2017, and are increasingly responsible for losses in the game ranching industry (De Waal 2009, Bergman et al. 2013, Schepers 2016. ...
Conference Paper
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South Africa has approximately 8,000 commercial small livestock farms and 5,800 communal/subsistence farmers throughout the country. Reported rates of small livestock loss to predation range from 3-13% and 0.5-19% from communal farming areas. A range of predators exist on the African continent, but in southern Africa major livestock losses are primarily due to black-backed jackal and caracal. South Africans have been managing caracals and jackals for over 300 years with no elimination of predation. During the aforementioned time frame, producers have used and/or developed a number of techniques including lethal, nonlethal, and integrated predator damage management to address predation losses. In the Karoo area of South Africa, one producer decided that a new way needs to be developed after losing over 60 lambs in a month, while practicing continuous removal of caracal and black-backed jackal. His integrated predator damage management system includes using a prototype nonlethal collar system for sheep and lambs. The collars are used to train dominant pairs of predators to avoid predation while maintaining their territories and keeping transient predators out of the area. The system has now gone into production in South Africa and is being distributed by its inventor.
... The situation has become so complex and polarized that a scientific assessment on the issue of predation on livestock in South Africa is currently ongoing (Kerley et al. 2017). Although some farmers are exploring non-lethal control methods (McManus et al. 2014), large-scale culling remains common on farmlands (Minnie et al. 2016), despite limited evidence of its effectiveness Du Plessis 2008, Bergman et al. 2013). The combination of compensatory reproduction and immigration in response to lethal management are considered important traits in the persistence of predator populations that are heavily hunted (Knowlton 1972, Frank andWoodroffe 2001), including jackals in South Africa (Minnie et al. 2016). ...
... Although some farmers are exploring non-lethal control methods (McManus et al. 2014), large-scale culling remains common on farmlands (Minnie et al. 2016), despite limited evidence of its effectiveness Du Plessis 2008, Bergman et al. 2013). The combination of compensatory reproduction and immigration in response to lethal management are considered important traits in the persistence of predator populations that are heavily hunted (Knowlton 1972, Frank andWoodroffe 2001), including jackals in South Africa (Minnie et al. 2016). For this reason, small-livestock farmers often blame protected areas for being a source for jackals and caracals, and many believe that those with territories in reserves regularly cross into farmlands to prey on their livestock. ...
... That suggests that there is no evidence for the belief amongst farmers in the area that these predators leave the protected area to predate sheep on farmland. This information could potentially help mitigate the conflict between small-livestock farmers and wildlife managers, although it is still likely that the protected area provides a source of dispersing predators to recolonize territories rendered vacant on farmland by culling efforts (Minnie et al. 2016). High relative abundance of livestock on farmland, together with our finding that jackals prefer livestock over similar-sized prey, suggest that reducing depredation will require that farmers reduce the availability of their livestock to predators. ...
Article
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The use of land for pastoralism is often associated with a reduction in the diversity and abundance of wildlife and influences conflict between farmers and predators worldwide. We explored differences in the diversity and relative abundance of medium and large animals on farmlands and a nearby protected area and compared these differences to prey consumed by 3 sympatric predators (black-backed jackal [Canis mesomelas], caracal [Caracal caracal], and leopard [Panthera pardus]) in the Karoo region of South Africa. All 3 predators, but especially jackals and caracals, are a source of conflict with small-stock farmers, many of whom believe that predators use the protected area as a base for raiding farmland. We determined predator diets using 657 scats collected on both land uses in subsequent years. Domestic ungulates dominated the farming landscape and comprised the bulk of prey in the scats of jackals and caracals as determined by the frequency of occurrence (42% and 25%, respectively), percent volume (47% and 32%, respectively), and ingested biomass. By contrast jackals and caracals in the reserve fed primarily on fruits and micromammals, respectively, with a lower ingested biomass of mammalian prey. No domestic sheep were in any of the scats in the reserve. We found leopard scats only in the reserve and they mostly contained wild ungulates. Dietary niche breadth and overlap were higher on farms than in the reserve and were attributed to the high consumption of domestic livestock by jackal and caracal. Dietary overlap between medium-sized predators and leopards was small. Caracals on farms and caracals and jackals in the reserve showed strong prey preference for wild mammals, whereas jackals on farms showed prey preference for goats and sheep over similar-sized wild mammals. Leopards showed preference for bushpig (Potamochoerus larvatus) and mountain-dwelling antelopes but consumed baboons (Papio ursinus) according to availability. Together these results fill a gap in our knowledge about jackal and caracal diets on farmland and dietary niche relationships between 3 sympatric predators in conflict with small-stock farmers in the semi-arid regions of South Africa. In terms of management, our results show that it is crucial that farmers protect their livestock from predators, even on farms where wild prey are abundant because of jackals' preference for sheep and goats over similar-sized wild mammals.
... Besides the obvious and immediate effects on population size, such anthropogenic mortality will also affect the behaviour, social structure (e.g. lions, Panthera leo, Snyman et al. 2015), demography (black-backed jackal, Canis mesomelas, Minnie et al. 2016b), reproduction (e.g. black-backed jackal, Minnie et al. 2016b; coyotes, Canis latrans, Sacks et al. 2005) and dispersal (e.g. ...
... lions, Panthera leo, Snyman et al. 2015), demography (black-backed jackal, Canis mesomelas, Minnie et al. 2016b), reproduction (e.g. black-backed jackal, Minnie et al. 2016b; coyotes, Canis latrans, Sacks et al. 2005) and dispersal (e.g. cougar, Puma concolor, Stoner et al. 2013) of these carnivores. ...
... Conversely, jackals on reserves are infrequently hunted-when they are hunted it is at a much lower intensity than surrounding farms-thereby creating a landscape with local variations in anthropogenic mortality (see "Methods"). A recent study investigating the demographics of jackals on farms and reserves suggests that this variation in anthropogenic mortality leads to the formation of a source-sink system, which may counter management actions aimed at reducing jackal densities and associated livestock losses on farms (Minnie et al. 2016b). A large number of demographic studies on hunted carnivores draw similar conclusions (e.g. ...
Article
Full-text available
Lethal carnivore management is a prevailing strategy to reduce livestock predation. Intensity of lethal management varies according to land-use, where carnivores are more intensively hunted on farms relative to reserves. Variations in hunting intensity may result in the formation of a source–sink system where carnivores disperse from high-density to low-density areas. Few studies quantify dispersal between supposed sources and sinks—a fundamental requirement for source–sink systems. We used the black-backed jackal (Canis mesomelas) as a model to determine if heterogeneous anthropogenic mortality induces a source–sink system. We analysed 12 microsatellite loci from 554 individuals from lightly hunted and previously unhunted reserves, as well as heavily hunted livestock- and game farms. Bayesian genotype assignment showed that jackal populations displayed a hierarchical population structure. We identified two genetically distinct populations at the regional level and nine distinct subpopulations at the local level, with each cluster corresponding to distinct land-use types separated by various dispersal barriers. Migration, estimated using Bayesian multilocus genotyping, between reserves and farms was asymmetric and heterogeneous anthropogenic mortality induced source–sink dynamics via compensatory immigration. Additionally some heavily hunted populations also acted as source populations, exporting individuals to other heavily hunted populations. This indicates that heterogeneous anthropogenic mortality results in the formation of a complex series of interconnected sources and sinks. Thus, lethal management of mesopredators may not be an effective long-term strategy in reducing livestock predation, as dispersal and, more importantly, compensatory immigration may continue to affect population reduction efforts as long as dispersal from other areas persists.
... This may be ascribed to a smaller body size and lower energy requirements (Carbone et al. 1999). In addition, generalist food habits (Lariviere 2004), smaller home ranges (Atwood et al. 2004), increased reproductive rate (Minnie et al. 2016a), ability to disperse over large distances (Lieury et al. 2015), and higher population densities (Roemer et al. 2009) could often, either singly or in concert, explain the persistence of mesopredator populations, even in the face of heavy persecution. ...
... Jackals and caracals are considered the major predators of small livestock on farmland in the Karoo (Du Plessis et al. 2015;Drouilly et al. 2018b) and there is growing concern about their impacts on small-to medium-bodied game species such as springbok (Antidorcas marsupialis- Klare et al. 2010;Minnie et al. 2016b). As a result, both predator species are heavily controlled, and large-scale lethal management remains common on farmlands (Minnie et al. 2016a) despite evidence showing that this approach is counter-productive (Bergman et al. 2013;Minnie et al. 2016aMinnie et al. , 2018b. It is estimated that over 17,000 black-backed jackals are killed annually by farm owners in the North West Province of South Africa (Thorn 2009), and 90,000 licenses were granted to cull jackals in the Western Cape Province in 2011 alone (James 2014). ...
... Jackals and caracals are considered the major predators of small livestock on farmland in the Karoo (Du Plessis et al. 2015;Drouilly et al. 2018b) and there is growing concern about their impacts on small-to medium-bodied game species such as springbok (Antidorcas marsupialis- Klare et al. 2010;Minnie et al. 2016b). As a result, both predator species are heavily controlled, and large-scale lethal management remains common on farmlands (Minnie et al. 2016a) despite evidence showing that this approach is counter-productive (Bergman et al. 2013;Minnie et al. 2016aMinnie et al. , 2018b. It is estimated that over 17,000 black-backed jackals are killed annually by farm owners in the North West Province of South Africa (Thorn 2009), and 90,000 licenses were granted to cull jackals in the Western Cape Province in 2011 alone (James 2014). ...
Article
Full-text available
Jackals (Canis mesomelas) and caracals (Caracal caracal) are considered major predators of small livestock on farms across South Africa, with both species being subjected to lethal control. Lethal management (i.e., culling) can result in differential responses in the population dynamics and demography of mesopredators. We examined the potential impacts that high population turnover, due to lethal management, may have on the genetic structure and diversity of jackal and caracal populations. We included mitochondrial markers to assess the movement of maternal lineages across the landscape as a proxy for dispersal. We further employed variable microsatellite markers to quantify levels of genetic diversity and relatedness among individuals. We found that high population turnover in both species may promote compensatory dispersal, which is consistent with the high levels of genetic diversity observed in both species. Structure analysis showed that the jackal population was comprised of 2 genetic clusters, while all the caracals belonged to a single nuclear genetic cluster. The weak differentiation between the jackal clusters (FST = 0.08), and the high level of inbreeding (FIS = 0.112) in the Central Karoo cluster, suggests that they likely represent demic populations. These data can be used as a baseline for ongoing population monitoring. Temporal monitoring of wildlife populations that are exposed to lethal management is important for a better understanding of the long-term effects on species ecology and survival success.
... mesopredator release; see Chapter 8). However, livestock predation by black-backed jackal and caracal is probably rooted in their ethological and ecological plasticity, which allows them to persist despite centuries of population reduction efforts (Minnie, Gaylard & Kerley, 2016a;Chapter 2). This, in turn, has exacerbated their impacts on the livestock industry. ...
... Black-backed jackal females have one litter per year, and litter size ranges between one and nine, depending on the female's body condition (Minnie et al., 2016a), social status (Loveridge & Nel, 2013), and anthropogenic mortality (see Box 7.2; Minnie et al., 2016a). Both parents help raise the pups, which remain in the den from August to November (Ferguson et al., 1983). ...
... Black-backed jackal females have one litter per year, and litter size ranges between one and nine, depending on the female's body condition (Minnie et al., 2016a), social status (Loveridge & Nel, 2013), and anthropogenic mortality (see Box 7.2; Minnie et al., 2016a). Both parents help raise the pups, which remain in the den from August to November (Ferguson et al., 1983). ...
Chapter
Full-text available
Globally, several carnivore species have been implicated as livestock predators, these ranging in body size from the mongoose (Herpestidae) (e.g. Minnie, 2009) to the tiger Panthera tigris (Gusset, Swarner, Mponwane, Keletile & McNutt, 2009; Van der Merwe, Avenant & Lues, 2009a) and bears (e.g. Li, Buzzard, Chen & Jiang, 2013). However, medium-sized canids and felids are most often implicated in livestock predation. For example, red foxes Vulpes vulpes – the most widely distributed canid species apart from domestic dogs Canis lupus familiaris – attack and kill livestock both in their natural and introduced ranges (Sillero-Zubiri, Hoffmann & MacDonald, 2004); coyotes Canis latrans and dingoes Canis lupus dingo are the dominant predators of livestock in North America and Australia, respectively (Sillero-Zubiri et al., 2004). In addition, golden jackals Canis aureus prey on livestock in Africa, Europe and the Middle East (e.g. Yom-Tov, Ashkenazi & Viner, 1995). Furthermore, the Eurasian lynx Lynx lynx and to a lesser extent bobcats Lynx rufus have been implicated in livestock predation in Europe and North America, respectively (see Inskip & Zimmermann, 2009 for review). In contrast to the Canidae, the larger species of the Felidae (e.g. leopard, Panthera pardus) are more often implicated as livestock predators, apart from caracal Caracal caracal and Eurasian lynx (Inskip & Zimmermann, 2009). In the southern African context, mesopredators – most notably black-backed jackals Canis mesomelas and caracal – are claimed to be the dominant predators of livestock (predominantly sheep and goats and to a lesser extent cattle) and valued wildlife species (van Niekerk, 2010; Chapter 3). Several reasons for the relatively large impact of mesopredators on the livestock industry have been suggested (e.g. mesopredator release; see Chapter 8). However, livestock predation by black-backed jackal and caracal is probably rooted in their ethological and ecological plasticity, which allows them to persist despite centuries of population reduction efforts (Minnie, Gaylard & Kerley, 2016a; Chapter 2). This, in turn, has exacerbated their impacts on the livestock industry.
... South African farmers' perception is that predator numbers are increasing (Avenant and Du Plessis 2008, Du Plessis 2013. Factors causing the possible increase in predator numbers include poor fencing, limited human presence, and the possibility that continuous predator removal operations over large parts in South Africa, especially over the last three decades, has led to compensatory immigration and breeding (Avenant and Du Plessis 2008, Minnie et al. 2016, 2018b. These perceptions are in accord with the decline in government support for commercial sheep farmers, including for fencing and predator control operations (Bergman et al. 2013, Natrass and Conradie 2018; the expansion of protected areas; the increase in game; weekend and hobby farms (Reed andKleynhans 2009, Du Plessis 2013); and an increase in farmer unemployment (Western Cape Department of Agriculture 2017). ...
... Many producers believe that mesocarnivores have to decrease drastically to reduce depredation to acceptable levels (Du Plessis et al. 2015). However, livestock predation by mesocarnivores is rooted in their ethological and ecological plasticity, which allows them to persist despite centuries of population reduction efforts (Bergman et al. 2013, Minnie et al. 2016, 2018a. ...
... Caracal and black-backed jackal occur throughout South Africa (Avenant et al. 2016, Minnie et al. 2016. They are the most important native predators that cause livestock losses (Blaum et al. 2009, Strauss 2009, Van Niekerk 2010, Thorn et al. 2012, Bergman et al. 2013, Badenhorst 2014, Kerley et al. 2017, and are increasingly responsible for losses in the game ranching industry (De Waal 2009, Bergman et al. 2013, Schepers 2016. ...
Article
Full-text available
South Africa has approximately 8,000 commercial small livestock farms and 5,800 communal/subsistence farmers throughout the country. Reported rates of small livestock loss to predation range from 3-13% and 0.5-19% from communal farming areas. A range of predators exist on the African continent, but in southern Africa major livestock losses are primarily due to black-backed jackal and caracal. South Africans have been managing caracals and jackals for over 300 years with no elimination of predation. During the aforementioned time frame, producers have used and/or developed a number of techniques including lethal, nonlethal, and integrated predator damage management to address predation losses. In the Karoo area of South Africa, one producer decided that a new way needs to be developed after losing over 60 lambs in a month, while practicing continuous removal of caracal and black-backed jackal. His integrated predator damage management system includes using a prototype nonlethal collar system for sheep and lambs. The collars are used to train dominant pairs of predators to avoid predation while maintaining their territories and keeping transient predators out of the area. The system has now gone into production in South Africa and is being distributed by its inventor.
... These techniques consist of lethal and nonlethal methods and are generally implemented as a precautionary (≈ preventative) measure to decrease the risk of livestock predation or as a remedial (≈ reactive) action following predation (PMF, 2016). In South Africa, many livestock producers persist in attempting to reduce predator numbers through unselective, lethal methods (Du Plessis, 2013;McManus, Dickman, Gaynor, Smuts & MacDonald, 2015;Minnie, Gaylard & Kerley, 2016). There are, however, an increasing number of producers who are moving away from an eradication-only approach to non-lethal and more target-specific methods (Minnie, 2009;Van Niekerk, 2010;Du Plessis, 2013;Badenhorst, 2014;Humphries, Hill & Downs, 2015;McManus et al., 2015;Schepers, 2016). ...
... year (between 39 and 54 jackals annually), he continued to lose more than 100 sheep a year (Humphries et al., 2015; also see Thomson, 1984). Additionally, Minnie et al. (2016) in a study on the effect of extensive shooting on black-backed jackal populations on livestock farms in the Eastern and Western Cape, found that jackal populations on these farms were generally younger and more unstable compared to populations on nearby reserves. This was because sustained shooting on the farms resulted in the disruption of the normal, mutually exclusive territorial system of black-backed jackals and created vacated areas for younger dispersers. ...
... This was because sustained shooting on the farms resulted in the disruption of the normal, mutually exclusive territorial system of black-backed jackals and created vacated areas for younger dispersers. Minnie et al. (2016) also demonstrated that the populations on the farmland compensated for population reductions by reproducing at a younger age and by carrying more foetuses (also see Loveridge, Searle, Murindagomo & MacDonald, 2007;Chapter 7). Minnie, Zalewski, Zalweska & Kerley (2018) also showed that shooting created to these farmers developing a dislike towards the protected wildlife and the prescribed management methods. ...
Chapter
The causes of human-predator conflict (HPC) are typically viewed from an anthropocentric perspective (see Redpath et al., 2013) and are consequently translated into costs incurred by humans through various animal behaviours (Aust, Boyle, Ferguson & Coulson, 2009; Barua, Bhagwat & Jadvav, 2013). Instances of HPC may originate where predators prey on livestock (Wang & Macdonald, 2006; Chaminuka, McCrindle & Udo, 2012), utilise resources of recreational value (Pederson et al., 1999; Skonhoft, 2006), damage human property (Gunther et al., 2004), pose a threat to the safety of humans (Loe & Roskaft, 2004; Thavarajah, 2008), or compete with other species of conservation or economic value (Engeman, Shwiff, Constantin, Stahl & Smith, 2002). In response, humans employ a range of management strategies to moderate the costs that they incur from HPC.
... These techniques consist of lethal and nonlethal methods and are generally implemented as a precautionary (≈ preventative) measure to decrease the risk of livestock predation or as a remedial (≈ reactive) action following predation (PMF, 2016). In South Africa, many livestock producers persist in attempting to reduce predator numbers through unselective, lethal methods (Du Plessis, 2013;McManus, Dickman, Gaynor, Smuts & MacDonald, 2015;Minnie, Gaylard & Kerley, 2016). There are, however, an increasing number of producers who are moving away from an eradication-only approach to non-lethal and more target-specific methods (Minnie, 2009;Van Niekerk, 2010;Du Plessis, 2013;Badenhorst, 2014;Humphries, Hill & Downs, 2015;McManus et al., 2015;Schepers, 2016). ...
... However, in a questionnaire study conducted on livestock farmers in Kwazulu-Natal, one of the respondents reported that over a period of three years, despite shooting black-backed jackals every year (between 39 and 54 jackals annually), he continued to lose more than 100 sheep a year (Humphries et al., 2015; also see Thomson, 1984). Additionally, Minnie et al. (2016) in a study on the effect of extensive shooting on black-backed jackal populations on livestock farms in the Eastern and Western Cape, found that jackal populations on these farms were generally younger and more unstable compared to populations on nearby reserves. This was because sustained shooting on the farms resulted in the disruption of the normal, mutually exclusive territorial system of black-backed jackals and created vacated areas for younger dispersers. ...
... This was because sustained shooting on the farms resulted in the disruption of the normal, mutually exclusive territorial system of black-backed jackals and created vacated areas for younger dispersers. Minnie et al. (2016) also demonstrated that the populations on the farmland compensated for population reductions by reproducing at a younger age and by carrying more foetuses (also see Loveridge, Searle, Murindagomo & MacDonald, 2007;Chapter 7). Minnie, Zalewski, Zalweska & Kerley (2018) also showed that shooting created to these farmers developing a dislike towards the protected wildlife and the prescribed management methods. ...
... Because of extirpations of large carnivores, black-backed jackals are the dominant predator over most of South Africa, including on small livestock farms where domestic sheep are often their main prey (Kamler et al. 2012a;Drouilly et al. 2018;Minnie et al. 2016Minnie et al. , 2018. Consequently, jackals are heavily persecuted on small livestock farms because of their real or perceived predation on livestock (Du Plessis et al. 2015;Minnie et al. 2016, Drouilly et al. 2018. ...
... Because of extirpations of large carnivores, black-backed jackals are the dominant predator over most of South Africa, including on small livestock farms where domestic sheep are often their main prey (Kamler et al. 2012a;Drouilly et al. 2018;Minnie et al. 2016Minnie et al. , 2018. Consequently, jackals are heavily persecuted on small livestock farms because of their real or perceived predation on livestock (Du Plessis et al. 2015;Minnie et al. 2016, Drouilly et al. 2018. In contrast, on many nature reserves, jackals are not hunted, or are hunted at a much lower intensity compared to livestock farms (Kamler et al. 2013b, Drouilly et al. 2018, Minnie et al. 2018. ...
... This was surprising given that betas made numerous forays to surrounding livestock farms, yet none attempted to establish territories there. Although the rate of philopatry by betas was higher than that observed in East Africa (24%; Moehlman 1986), our results were consistent with those reported by Minnie et al. (2016) in South Africa, who reported that on reserves with low human-caused mortality, only about 50% of female black-backed jackals that were 3-4 year old had become pregnant, suggesting a relatively high proportion of older jackals were betas. Beta females staying in their natal ranges for 2 subsequent litters to help their parents was reported previously for black-backed jackals (Moehlman 1979, Ferguson et al. 1983) and coyotes (Andelt 1985, Gese et al. 1996, Kamler and Gipson 2000, so it may not be unusual behavior for medium-sized canids. ...
Article
Full-text available
We radio‐tracked 15 black‐backed jackals (Canis mesomelas) from 8 adjacent family groups on Benfontein Game Farm (i.e., Benfontein) in South Africa to investigate their movement patterns and social organization. Jackal family groups consisted of mated pairs (alphas), 0–3 nonbreeding adults (betas), and pups, depending on the season. Mean (±SE) home‐range size of alphas (9.4 ± 1.2 km2, n = 6) did not differ (P = 0.766) from betas (9.8 ± 0.7 km2, n = 8). Most beta jackals (8 of 10) remained philopatric on Benfontein, apparently because of the high density of springbok (Antidorcas marsupialis), their preferred prey. Three of 5 alphas and all 8 betas went on extraterritorial forays (i.e., forays). Generally, betas spent more of their active time on forays (2–20% of time) than alphas (0–3%; P = 0.048), and betas went farther on forays (2–8 km) than alphas (2–3 km; P = 0.003). The number of forays differed (P < 0.001) among seasons; most forays occurred during summer (64%) when jackals visited neighboring livestock farms, apparently to predate on domestic sheep. Overall, our results indicate forays by jackals are affected by social status, seasonal availability of preferred prey, and the reproductive cycle of jackals. To reduce jackal predation on livestock farms near reserves, we recommend that preventative measures (e.g., use of herders, jackal control activities) be increased during summer when jackals are most likely to travel outside reserves. © 2019 The Wildlife Society. On a reserve in South Africa, forays by black‐backed jackals were affected by social status, seasonal availability of preferred prey, and the reproductive cycle of jackals. We recommend several preventative measures to reduce jackal predation on livestock farms near reserves, based on the preferred prey of jackals and the periods when jackals are most likely to travel outside of reserves.
... Migration in response to culling has also been shown in the red fox (Gentle et al., 2007;Lieury et al., 2015), resulting in source-sink dynamics where animals in source populations, outside of the control area, migrate to areas of higher mortality, known as sinks, created by culling. Other predators have demonstrated similar responses; for example, culling of black-backed jackals (Canis mesomelas) has been shown to lead to compensatory birth effects, and increased migration into the control areas (Minnie, Gaylard, & Kerley, 2016). Some preliminary evidence suggests that the most effective control measures can select for animals that avoid that measure (Allsop et al., 2017;Minnie et al., 2016); although the response can be expected to be context-specific. ...
... Other predators have demonstrated similar responses; for example, culling of black-backed jackals (Canis mesomelas) has been shown to lead to compensatory birth effects, and increased migration into the control areas (Minnie, Gaylard, & Kerley, 2016). Some preliminary evidence suggests that the most effective control measures can select for animals that avoid that measure (Allsop et al., 2017;Minnie et al., 2016); although the response can be expected to be context-specific. Modeling has shown that undesirable "education" of invasive predators can "create and maintain an uncatchable segment in the population with respect to a given control tool" (p.1234; [Bischof & Zedrosser, 2009]). ...
... This would make them less lethal to the native mammals that they have been "conditioned" not to attack. Another advantage of keeping "less lethal" foxes in a given landscape, is that they could prevent compensatory increases in female fox fecundity that has been observed in situations where fox (Berry & Kirkwood, 2010;Marlow et al., 2016) and black-backed jackal (Minnie et al., 2016) numbers have been artificially reduced. ...
Article
Full-text available
Abstract Predation of threatened fauna by native and introduced predators can drive extinction and prevent population recovery. Most predator management involves exclusion or culling. Evidence suggests that exclusion may have detrimental effects on a prey species' predator awareness. At the same time, culling can cause selection of control‐resistant predators. There is increasing interest in harnessing evolutionary processes to drive adaptation of threatened fauna to cope, but there is limited attention on trying this from the predator direction. We need to shift the survival advantage away from predators that avoid lethal control, and go on to kill, towards those that demonstrate behaviors that reduce impact on threatened fauna. Instead of driving undesirable predator selection, could we select through management actions desirable traits to make them “less lethal” to threatened fauna? We draw on experimental research on predator aversion that suggests there may be an alternative way to mitigate the impacts of predators, while maintaining the learning opportunities of prey species. Using the case study of the invasive red fox in Australia, we propose a conceptual framework within which future research and management could occur to select for these desirable traits in predators and develop practical regimes for predator impact mitigation.
... Because of extirpations of large carnivores, black-backed jackals are the dominant predator over most of South Africa, including on small livestock farms where domestic sheep are often their main prey (Kamler et al. 2012a;Drouilly et al. 2018;Minnie et al. 2016Minnie et al. , 2018. Consequently, jackals are heavily persecuted on small livestock farms because of their real or perceived predation on livestock (Du Plessis et al. 2015;Minnie et al. 2016, Drouilly et al. 2018. ...
... Because of extirpations of large carnivores, black-backed jackals are the dominant predator over most of South Africa, including on small livestock farms where domestic sheep are often their main prey (Kamler et al. 2012a;Drouilly et al. 2018;Minnie et al. 2016Minnie et al. , 2018. Consequently, jackals are heavily persecuted on small livestock farms because of their real or perceived predation on livestock (Du Plessis et al. 2015;Minnie et al. 2016, Drouilly et al. 2018. In contrast, on many nature reserves, jackals are not hunted, or are hunted at a much lower intensity compared to livestock farms (Kamler et al. 2013b, Drouilly et al. 2018, Minnie et al. 2018. ...
... This was surprising given that betas made numerous forays to surrounding livestock farms, yet none attempted to establish territories there. Although the rate of philopatry by betas was higher than that observed in East Africa (24%; Moehlman 1986), our results were consistent with those reported by Minnie et al. (2016) in South Africa, who reported that on reserves with low human-caused mortality, only about 50% of female black-backed jackals that were 3-4 year old had become pregnant, suggesting a relatively high proportion of older jackals were betas. Beta females staying in their natal ranges for 2 subsequent litters to help their parents was reported previously for black-backed jackals (Moehlman 1979, Ferguson et al. 1983) and coyotes (Andelt 1985, Gese et al. 1996, Kamler and Gipson 2000, so it may not be unusual behavior for medium-sized canids. ...
Article
Full-text available
We used radiocollars and GPS collars to determine the movements and habitat selection of golden jackals (Canis aureus) in a seasonally dry deciduous forest with no human settlements in eastern Cambodia. We also collected and analyzed 147 scats from jackals to determine their seasonal diet and prey selection. The mean (± SE) annual size of home-range ranges (47.1 ± 2.5 km 2 ; n = 4), which were mutually exclusive between mated pairs, was considerably larger than that previously reported for this species, resulting in an extremely low density (0.01 jackal/km 2). The unusually large home ranges and low density probably were due to the harsh dry season when most understory vegetation is burned and nearly all waterholes dry up, thereby causing a large seasonal decline in the availability of small vertebrate prey. Resident groups consisted of an alpha pair, but no betas, and were situated only in areas not occupied by leopards (Panthera pardus) and dholes (Cuon alpinus). Jackals avoided dense forests and streams, and had a strong selection for dirt roads, possibly to avoid larger predators. Overall the jackal diet was diverse, with at least 16 prey items identified, and there was no significant difference in diet composition between the cool-dry and hot-dry seasons. Scat analysis showed that the main food items consumed by jackals were processional termites (Hospitalitermes spp.; 26% biomass consumed), followed by wild pig (Sus scrofa; 20%), muntjac (Muntiacus vaginalis; 20%), and civets (17%). Compared to available biomass, jackals were not random in their consumption of ungulates because muntjac were selectively consumed over larger ungulate species. Dietary overlap with dholes and leopards was relatively low, and consumption patterns indicated jackals were preying on ungulates rather than scavenging from kills of larger carnivores. Our results showed that the jackal is an extremely adaptable and opportunistic species that exhibits unique behaviors to survive in an extreme environment near the edge of its distribution.
... To reduce predation on livestock, farmers often resort to lethal management (Thorn et al., 2013;Treves & Karanth, 2003), which may disrupt social structures resulting in predators compensating reproductively by having higher proportions of young breeders and larger litter sizes (Haber, 1996;Minnie, Gaylard et al., 2016). Disrupting social structures in territorial species may also create vacant spaces which facilitates compensatory immigration (Minnie, Zalewski, et al., 2018;Pulliam, 1988). ...
... latrans;Knowlton et al., 1999) and red foxes (Vulpes vulpes; Kierepka et al., 2017)], jackals show physiological and behavioural flexibility to local conditions (e.g. compensatory reproduction and immigration (Minnie, Gaylard et al., 2016;Minnie, Zalewski, et al., 2018)), resulting in lethal management having little effect on jackal densities (Thorn et al., 2013). ...
... Our study is consistent with Tensen et al. (2018) that lethal management thus far does not have a negative effect on genetic diversity of jackals in the study area. Genetic diversity may be maintained through compensatory migration within and from outside the study area, as it is not a closed system, whereas social/family structure may be maintained by compensatory reproduction (Minnie, Gaylard et al., 2016). Similar suggestions are reported for lethally managed coyote (Kierepka et al., 2017), red fox, (Cavallini & Santini, 1996;Marlow et al., 2016), wolverine, Gulo gulo (Gervasi et al., 2015) and cougar, Pumo concolor (Robinson et al., 2008). ...
Article
Globally, levels of human–wildlife conflict are increasing as a direct consequence of the expansion of people into natural areas resulting in competition with wildlife for food and other resources. By being forced into increasingly smaller pockets of suitable habitat, many animal species are at risk of becoming susceptible to loss of genetic diversity, inbreeding depression and the associated inability to adapt to environmental changes. Predators are often lethally controlled due to their threat to livestock. Predators such as jackals (black backed, golden and side striped; Canis mesomelas, C. aureus and C. adustus, respectively), red foxes (Vulpes vulpes) and coyotes (C. latrans) are highly adaptable and may respond to ongoing persecution through compensatory reproduction such as reproducing at a younger age, producing larger litters and/or compensatory immigration including dispersal into vacant territories. Despite decades of lethal management, jackals are problematic predators of livestock in South Africa and, although considered a temporary measure, culling of jackals is still common. Culling may affect social groups, kinship structure, reproductive strategies and sex‐biased dispersal in this species. Here, we investigated genetic structure, variation and relatedness of 178 culled jackals on private small‐livestock farms in the central Karoo of South Africa using 13 microsatellites. Genetic variation was moderate to high and was similar per year and per farm. An absence of genetic differentiation was observed based on STRUCTURE, principal component analysis and AMOVA. Relatedness was significantly higher within farms (r = 0.189) than between farms (r = 0.077), a result corroborated by spatial autocorrelation analysis. We documented 18 occurrences of dispersal events where full siblings were detected on different farms (range: 0.78–42.93 km). Distance between identified parent–offspring varied from 0 to 36.49 km. No evidence for sex‐biased dispersal was found. Our results suggest that in response to ongoing lethal management, this population is most likely able to maintain genetic diversity through physiological and behavioural compensation mechanisms. Predators such as the black‐backed jackal are often lethally controlled due to their threat to livestock, but are highly adaptable and may respond to ongoing persecution through compensatory reproduction and/or immigration. We investigated the genetic structure, variation and relatedness of 178 culled jackals on private small‐livestock farms in the central Karoo of South Africa using 13 microsatellites. Genetic variation was moderate to high, an absence of genetic differentiation was observed and relatedness was significantly higher within farms (r = 0.189) than between farms (r = 0.077). Our results suggest that in response to ongoing lethal management, this population is possibly maintaining genetic diversity through physiological and behavioural compensation mechanisms.
... The high level of persecution of jackals in South Africa is controversial (Nattrass, Drouilly, & O'Riain, 2019). Although intensive jackal control can significantly reduce jackal densities on livestock farms compared to nearby reserves (Kamler et al., 2013), others believe persecution does not affect jackal densities due to compensatory mechanisms and immigration (Minnie, Gaylard, & Kerley, 2016;Minnie, Zalewski, et al., 2018). Nonetheless, under natural condition with large carnivores present, jackals might experience high mortality levels similar to those in human-hunted populations. ...
... pardus; Schaller, 1972;Estes, 1991), cheetahs (Acinonyx jubatus; and African wild dogs (Lycaon pictus; Kamler, Davies-Mostert, Hunter, & Macdonald, 2007), yet the effects of these natural mortalities on jackal populations have never been quantified. Similarly, although the effects of human-caused mortalities on the genetic and population structure of jackals have been reported (Minnie, Gaylard, et al., 2016;Minnie, Zalewski, et al., 2018;Tensen, Drouilly, & van Vuuren, 2018), the effects of human-caused mortalities on the annual survival of a jackal population have never been determined. ...
... On HWE, despite the lack of human hunters, jackals had survival that was similar to BNR, primarily because of 4 deaths to leopard predation. Jackals are likely to have evolved in ecosystems with high levels of mortalities from large carnivores and apparently compensate for increased mortality by having high reproductive rates, helping to explain why jackals can persist on private farmlands in South Africa despite high rates of human-caused mortalities (Minnie, Gaylard, et al., 2016). Major limitations of our research were that our two study sites occurred in different habitats with presumably different food resources, at different times, and in different countries. ...
... Predator management may have both perverse outcomes (e.g. Minnie, Gaylard & Kerley (2016) show earlier reproduction in managed jackal populations) and unexpected positive outcomes for biodiversity (e.g. Minnie, Kerley & Boshoff (2015) show that livestock are sometimes withdrawn from high risk areas, leading to a relaxation of domestic herbivore pressures). ...
... Clearly, and as demonstrated in this Scientific Assessment, the system is complex, and there may be unforeseen or perverse outcomes of management interventions (e.g. Minnie et al., 2016). The PredSA assessment identifies many management approaches to mitigating livestock predation. ...
Chapter
Full-text available
Livestock predation and its management in South Africa: a scientific assessment (Eds Kerley, G.I.H., Wilson, S.L. & Balfour, D.). Centre for African Conservation Ecology, Nelson Mandela University, Port Elizabeth,
... Research on coyotes (Canis latrans) and black-backed jackals (C. mesomelas) indicates that human-caused mortality can generate compensatory reproduction that might augment the number of breeding packs and elevate the predator density, both of which might raise the risk for domestic animals (Knowlton et al., 1999;Minnie et al., 2016). ...
... Ecologists have long understood that release from competition leads to prey switches, range shifts, and other flexible, behavioral responses by surviving predators. For a particularly relevant example in our context, mesopredator release has been substantiated repeatedly after the removal of a larger, dominant competitor (Prugh et al., 2009;Allen et al., 2016;Minnie et al., 2016;Krofel et al., 2017;Newsome et al., 2017). ...
Article
Full-text available
Rapid, global changes, such as extinction and climate change, put a premium on evidence-based, environmental policies and interventions, including predator control efforts. Lack of solid scientific evidence precludes strong inference about responses of predators, people, and prey of both, to various types of predator control. Here we formulate two opposing hypotheses with possible underlying mechanisms and propose experiments to test four pairs of opposed predictions about responses of predators, domestic animals, and people in a coupled, dynamic system. We outline the design of a platinum-standard experiment, namely randomized, controlled experiment with cross-over design and multiple steps to blind measurement, analysis, and peer review to avoid pervasive biases. The gold-standard has been proven feasible in field experiments with predators and livestock, so we call for replicating that across the world on different methods of predator control, in addition to striving for an even higher standard that can improve reproducibility and reliability of the science of predator control.
... However, despite >350 years of persecution, jackals and caracals have been relatively resilient to lethal management. In response to high population turnover, compensatory immigration was observed in both species (Minnie et al., 2016;Tensen et al., 2018) and compensatory reproduction was reported in jackals (Minnie et al., 2016). Non-lethal techniques, such as selective exclusion fences, may potentially be more efficient as a management tool for predator control, but more research should be conducted to address these issues. ...
... However, despite >350 years of persecution, jackals and caracals have been relatively resilient to lethal management. In response to high population turnover, compensatory immigration was observed in both species (Minnie et al., 2016;Tensen et al., 2018) and compensatory reproduction was reported in jackals (Minnie et al., 2016). Non-lethal techniques, such as selective exclusion fences, may potentially be more efficient as a management tool for predator control, but more research should be conducted to address these issues. ...
... Recent research from the Karoo using satellite-tagged jackals to identify feeding sites on farmland indicates that > 80% of livestock feeding events were the result of a kill rather than a scavenging event 1971a, b, Hall-Martin & Botha 1980, Moehlman 1987, Bernard & Stuart 1992, Bingham & Purchase 2002. Litter size varies from one to eight pups with a mean of about four (Bothma 1971b, Bingham & Purchase 2002 and is associated with food availability and the mother's age (Moehlman 1979, 1987, Minnie et al. 2016). Pups typically disperse after about six months but may stay and help protect and provision subsequent litters ( Moehlman 1979, Ferguson et al. 1983). ...
... Such a plastic behavioural repertoire has implications also for research methodologies seeking to pin down the ecological impact of lethal management of jackals. For example, Minnie et al. (2016) found that jackals culled in national parks were older than those culled on surrounding farmlands and concluded that this provided supportive evidence for 'source-sink' dynamics (juvenile jackals dispersing from protected areas onto farms). Yet the differing age structure of culled jackals may also reflect the fact that older jackals on farms, with greater experience of hunting and a repertoire of adaptive behaviour, were more difficult to cull than the juveniles. ...
Article
The black‐backed jackal Canis mesomelas, henceforth jackal, has re‐emerged as a threat to South African sheep farmers. This sparked contestation between farmers and conservationists over the reasons for their return and the relative merits of lethal and non‐lethal approaches to protecting livestock. Three separate reviews of the scientific literature converged on the same broad conclusion that lethal control of jackals is probably ineffective, but that more scientific research is necessary, especially on farms. We draw on historic evidence and recent research across a range of disciplines to show that jackal diet and behaviour varies regionally and alter in response to changing threats and opportunities. More data will not support generalisable conclusions and have already been eclipsed by broad‐scale changes in the political, economic and ecological landscapes of South Africa. Reduced government support for farmers, rising production costs and falling product prices, together with an increasing frequency of droughts, have conspired to weaken the collective management hand of farmers and, ultimately, contributed to a decline in the sheep farming industry. Many sheep farmers have sold their land to non‐commercial ‘lifestyle' farmers or expanding nature reserves, creating a growing network of safer spaces for jackals to persist, from which their offspring can sink into neighbouring commercial farmland. When these landscape‐level changes are combined with the wide phenotypic plasticity and catholic diet of the jackal, we should be neither surprised at their resurgence nor contented with suggestions that more ecological research is likely to facilitate any sustainable solutions. Black‐backed jackal (Canis mesomelas) diet and behaviour varies regionally and alters in response to changing threats and opportunities. Universalisable or sustainable solutions to the conflict between jackals and sheep farmers in South Africa are unlikely.
... The overall adaptability of jackals is also evident from their widespread occupation of areas under human settlement (livestock farms and wildlife farms; Humphries et al. 2015) and their recolonization of areas where they were historically eradicated (Stuart and Stuart 2015;Minnie et al. 2016). Anthropogenically altered landscapes, such as livestock and wildlife farms, often reduce the availability of natural resources but provide easily obtainable prey in the form of livestock and privately owned wildlife. ...
... Furthermore, the distinct δ 13 C seen in cattle samples (strong C 4 ) is seldom seen in jackal scat samples from the livestock farm (< 10%) and given the size of cattle and limited reports of cattle predation by jackals (personal communication A. Lombaard 2019), cattle predation by jackals is extremely unlikely, confirming prediction 5. However, given the behavioral flexibility often reported in this species and their known cross-boundary movement (Minnie et al. 2016(Minnie et al. , 2018Nattrass et al. 2019Nattrass et al. , 2020 which could lead to different isotopic signatures between the controlled and protected populations.), it is possible that jackals are moving onto bordering farms and preying upon livestock that exhibit different isotopic signals due to supplemented livestock feeding regimes seen on neighboring farms during winter. ...
Article
Wildlife and livestock farms around the world have eradicated large predators, leaving an empty niche for mesopredators to occupy. In South Africa, black-backed jackals (Canis mesomelas) are a widely distributed mesopredator that actively prey on wildlife and livestock. Despite the documented economic losses often associated with livestock predation in South Africa and abroad, research in many areas of canid ecology has received little attention. Using standard isotopic analysis (SIA), we conducted inter-population and jackal–prey isotopic comparisons by analyzing the δ13C and δ15N signals of jackal scat and prey hair samples (livestock and rodents) collected in sites of varied human exposure across multiple seasons. C3 signals dominated our results despite the C4 grasslands that are characteristic of the study sites. Our results indicated inter-population variation with a C3/C4 mixed diet in reserve and livestock farm samples, and a C3 orientated diet in wildlife farm samples. There were significant differences in the δ13C between seasons in the livestock and wildlife farm populations but not in the reserve population. δ15N had strong support for inter-population differences and no support for seasonal variation. Jackal isotopic niche breadths differed between populations, overlapped moderately with rodent prey and indicated almost no overlap with livestock. Our results highlight the feeding plasticity of jackals and the impact of human activities on resource availability and the subsequent feeding choices in canids. Using SIA, we accurately determined that livestock form a limited, if not completely absent, constituent of certain jackal populations. We strongly encourage the complementary use of SIA in dietary studies and wildlife management practices.
... For example, where Black-backed jackals have been culled in areas where food is not limiting, conspecifics are known to emigrate from areas of relatively high density to areas of low density, i.e., into those areas where individuals have been removed. Furthermore, Black-backed jackals are known to increase their rate of reproduction in areas where they are actively persecuted (Minnie, Gaylard & Kerley 2016). ...
... Accurate and robust estimates of Black-backed jackal population density are lacking in the scientific literature (Minnie et al. 2018;Minnie, Gaylard & Kerley 2016). We aimed to determine whether it would be possible to use REM and gREM estimators, in conjunction with commercially available cameras, to develop a repeatable method for monitoring of Black-backed jackal population densities on wildlife reserves, with the intention of possibly using such a method, once validated, on a wide variety of landscapes and land management regimes (potentially including stock farming enterprises). ...
... High population densities of black-backed jackals are a direct consequence of agriculture (concentration of food and poor disposal of carcases) (Humphries, Hill & Downs, 2015). Lethal control may be an ineffective measure of population control for black-backed jackals because removed individuals are simply replaced by others (Humphries, Hill & Downs, 2015;Minnie, Gaylard & Kerley, 2016). Deliberate control of problematic species may additionally result in 'compensatory reproduction' which has been shown to be present in several carnivore species, including blackbacked jackals, Canadian lynxes (Lynx canadensis), Eurasian lynxes (Lynx lynx), red foxes and side-striped jackals (Canis adustus) (Parker et al., 1983;Harris & Smith, 1987;Bingham & Purchase, 2002;Bagrade et al., 2016;Minnie, Gaylard & Kerley, 2016). ...
... Lethal control may be an ineffective measure of population control for black-backed jackals because removed individuals are simply replaced by others (Humphries, Hill & Downs, 2015;Minnie, Gaylard & Kerley, 2016). Deliberate control of problematic species may additionally result in 'compensatory reproduction' which has been shown to be present in several carnivore species, including blackbacked jackals, Canadian lynxes (Lynx canadensis), Eurasian lynxes (Lynx lynx), red foxes and side-striped jackals (Canis adustus) (Parker et al., 1983;Harris & Smith, 1987;Bingham & Purchase, 2002;Bagrade et al., 2016;Minnie, Gaylard & Kerley, 2016). Large scale compensatory reproduction further manifests in increased fecundity, larger proportion of breeding females, increased reproductive lifespan, and a decrease in age at first reproduction of the targeted species (Kerley, Wilson & Balfour, 2018). ...
... Lethal control may not always be economically viable if loss of regulatory services by predators results in high costs where wild herbivores compete for forage with domestic stock (Wicks & Allen 2012). Lethal control can also disrupt social structure, exacerbating livestock predation problems (Wallach et al. 2009), or lead to compensatory reproduction, thereby minimising the effect of control (Minnie, Gaylard & Kerley 2016;. A range of non-lethal alternatives exist that can assist mitigation of livestock predation problems and encourage coexistence (Shivik 2006;Stone et al. 2017). ...
Thesis
Full-text available
This thesis fills knowledge gaps regarding spatio-temporal interactions between sympatric carnivores, mesopredator risk mitigation behaviour, and thus, the mechanisms that enable coexistence. In the Anthropocene biodiversity crisis, discerning how and when diversity is maintained is critical. Employing a robust multi-method approach, a model study system was used to examine the top-down effects of wolves, Canis lupus and Eurasian lynx, Lynx lynx, upon red fox, Vulpes vulpes in Plitvice Lakes National Park, Croatia. Chapter Two utilises novel foraging experiments, combining camera traps with the giving-up density (GUD) framework. Foxes responded to wolf urine by taking less food, spending less time at patches, leaving at higher quitting harvest rates, and adjusting their behaviour when at patches, spending less time foraging and more time being vigilant and sniffing the ground. Chapter Three examines spatial relationships using occupancy modelling. Foxes were not spatially excluded by large carnivores, but were in fact attracted to them (or at least the same conditions) and more detectable in their presence. The positive association was most strongly related to lynx, however, conversely, foxes responded elusively towards human activity. Chapter Four examines temporal relationships using kernel density estimates, circular statistics and nocturnality risk ratios. Fox activity overlapped with other carnivores but avoided peak activity periods, having significantly different record distributions. Foxes were more nocturnal in higher intensity large carnivore presence, seemingly using the cover of darkness to remain safe. High human activity however mediated this interaction, decreasing its strength. Subtle temporal avoidance and fine-scale spatio-temporal risk mitigation strategies can enable mesopredator access to resources and predator coexistence in the presence of intraguild aggression. Where food subsidies are absent, humans may increase mesopredator elusiveness but may also offer some level of temporal shielding from large carnivores. Protected area management should consider ecological baselines and the effects of human disturbance.
... However, less attention has been directed towards recruitment through immigration into local populations. Recent studies have documented the ineffectiveness of culling efforts for red foxes Vulpes vulpes in agricultural areas in England (Baker and Harris 2006) and France (Lieury et al. 2015), and black-backed jackals Canis mesomelas in South Africa (Minnie et al. 2015) due to compensatory immigration across spatially-structured populations. Additionally, a meta-analysis of mesopredator removal studies found variable and largely unsuccessful results in lowering coyote populations through removals (Conner and Morris 2015). ...
Article
Full-text available
Ideal despotic distribution theory and resource dispersion theory predict that individuals in populations of territorial species arrange themselves in space according to dominance and resource dispersion. When available territories are saturated, this can result in competition for preferred territories. Recently, transience in coyote populations was suggested as an advantageous life history strategy, even though transients may incur higher mortality and do not typically contribute reproductively to the population at that time. Here we assess potential types of biding, or awaiting better territory opportunities, in a highly-exploited coyote population in Virginia, USA. We used relocation data from coyotes collared from July 2011-March 2014 to classify residents and transients based on a 95% home range area over a three-month moving window. We estimated home range stability as the distance between successive activity centers and compared it between subadults and adults. We used home range stability relative to home range area to identify extra-territorial excursions and territory turnover, or resident shifts into adjacent territories. Some coyotes adhered to the traditional form of transience, occupying very large home ranges or biding areas overlapping several resident territories, until a territory became vacant. Conversely, other individuals displayed evidence of resident territory turnover, suggesting individuals may use low quality territories as biding areas, waiting for better quality territories to become vacant. We suggest this biding population provides the capacity for rapid compensatory immigration. In response to high levels of mortality in exploited coyote populations, removal of individuals from territories may result in immediate colonization by another individual, confounding efforts to reduce overall coyote density. Thus, transience and biding may regulate population density and be a potentially advantageous life history strategy and may have implications for management of saturated populations of social predators.
... The home ranges of jackals in our study were, however, substantially smaller and across a narrower range than those in farmlands with a similar grassland habitat (MCP 95% varying from 5.02 km 2 to 1 300 km 2 , Humphries et al. 2016) although this broad range seems to have resulted from the transient behaviour of four of the five jackals in their study. Similarly, F-A-80438 conducted an atypical long-distance foray, which was possibly because of a search for a vacant territory in the bordering farmlands (Minnie et al. 2016b(Minnie et al. , 2018. Large variations in space use occurs between jackals of different ages (Humphries et al. 2016) and although our sample size was small, home ranges and space use were larger in subadults than adults, aligning with prediction 1 (subadult jackals would have larger annual home ranges than adults) and previous studies on jackal home ranges ( Table A for mean and error values of three jackals in our study suggest that M-SA-80435 and F-SA-80439 belong to the same social group (family group) with an annual home range overlap of greater than 50% (Ferguson et al. 1983;Loveridge and Macdonald 2001;Kamler et al. 2019). ...
Article
An animal’s ability to traverse a landscape and utilise available resources is vital for its survival. The movement patterns of an animal provide insight into space use, activity patterns and ecological requirements that are imperative for successful farming and wildlife management practices. Home ranges are often used as a measurement of space use, which provides a quantitative value of an animal’s movement patterns in relation to various biological factors. A factor that is often overlooked in the analysis of movement patterns is the effect of moon phase, despite its known impact on the activity and hunting success of nocturnal predators. We live-trapped, radio-collared and monitored five black-backed jackals (Canis mesomelas) in the Golden Gate Highlands National Park, South Africa, between 2018 and 2019 to determine the impact of various environmental factors on movement patterns. Annual home ranges varied between individuals, were larger in subadults and overlapped between three jackals. Space use and travel velocity suggested a crepuscular activity pattern with a reliance on nocturnal activity and limited diurnal activity. Individual space use suggested variation between moon phases, although overall variation was negligible. Jackals travelled farther during new moon, compared with full moon, with the most notable difference between 23:00 and 04:00. Our results suggest that jackal behaviour does not align with the predation risk hypothesis. Space use and travel velocities varied between seasons, possibly because of differences in activity during mating and pupping periods. Our study confirms the flexibility in jackal space use and suggests a possible relationship with moon phase. To properly understand movement patterns at an individual and population level, we encourage additional research about jackals and various environmental factors via multidisciplinary collaborations.
... Thus, both of Abrams' (2009) hypotheses for mechanisms of overcompensation and the Hydra effect are plausible for these species. These effects may be important in efforts to control mosquitoes and other pests, wherein a human intervention is the extrinsic source of mortality (Agudelo-Silva and Spielman 1984, Walker and Lynch 2007, Zipkin et al. 2009, Minnie et al. 2016. ...
Article
Overcompensation occurs when added mortality increases survival to the next life‐cycle stage. Overcompensation can contribute to the Hydra Effect, wherein added mortality increases equilibrium population size. One hypothesis for overcompensation is that added mortality eases density‐dependence, increasing survival to adulthood (“temporal separation of mortality and density dependence”). Mortality early in the life cycle is therefore predicted to cause overcompensation, whereas mortality later in the life cycle is not. Another hypothesis for overcompensation is that threat of mortality (e.g., from predation) causes behavioral changes that reduce overexploitation of resources, allowing resource recovery, and increasing production of adults (“prudent resource exploitation”). Behaviorally active predation cues alone are therefore predicted to cause overcompensation. We tested these predictions in two experiments with larvae of two species of Aedes. As predicted, early mortality yielded greater production of adults, and of adult females, and greater estimated rate of population increase than did later mortality. Addition of water‐borne predation cues usually reduced browsing on surfaces in late‐stage larvae, but contrary to prediction, resulted in neither significantly greater production of adult mosquitoes nor significantly greater estimated rate of increase. Thus we have strong evidence that timing of mortality contributes to overcompensation and the Hydra effect in mosquitoes. Evidence that predation cues alone can result in overcompensation via prudent resource exploitation is lacking. We expect the overcompensation in response to early mortality will be common in organisms with complex life cycles, density dependence among juveniles, and developmental control of populations. This article is protected by copyright. All rights reserved.
... Animals vary behavioural and life-history responses to the level of perceived and realized risk (Lima and Dill 1990;Creel and Christianson 2008;Martin and Briskie 2009;LaManna and Martin 2016;Minnie et al. 2016). In the context of a nest-box experiment, we tested the hypothesis that predator scent in a nest box will enhance perceived risk to adult starlings, thus affecting use of the site, as well as reproduction. ...
Article
Full-text available
Indirect predator cues near nests have been shown to enhance perceived predation risk and associated antipredator behaviours in breeding animals across taxa and particularly with birds. We hypothesized that scent from the raccoon (Procyon lotor (Linnaeus, 1758)) inside nest boxes would, despite being an evolutionarily unique predator, enhance perceived risk to the European Starling (Sturnus vulgaris (Linnaeus, 1758)), thus reducing use of treated sites and reproduction. During early spring, starlings selected from nest boxes treated with equal volumes of predator scent, a novel odour, or water (n = 40 boxes per treatment). We evaluated effects of treatment on reproductive traits via generalized linear models. Starlings established nest bowls in 61% of nest boxes (predator scent, n = 27 boxes; novel odour, n = 24 boxes; control (water), n = 22 boxes); clutches were laid in 68 boxes. We observed no effects of treatment on the likelihood of a clutch (≥1 egg) or nest failure. Further, we found no treatment effects on date of first egg, clutch size, or hatchling number. We conclude that starling antipredator response to enhanced, indirect risk of nest predation is contingent upon a combination of predator cues, as well as direct or indirect experience with nest predation.
... 2016). Poor carnivore management may be responsible for increased mesopredator abundance (Minnie et al. 2016). ...
... This home range estimate of 45.47 km 2 is consistent with those from previous studies, with territory sizes ranging from 2.1 km 2 to 91.5 km 2 (Ferguson et al. 1983;Kaunda 2001;Kalmer et al. 2012). Although studies on farmlands are limited, Humphries et al. (2016) found that the home range of a male jackal in the more mesic KwaZulu-Natal was 11.4 ± 4.3 km 2. This is considerably smaller than the home range estimated for this study in the Free State and may be explained by differences in hunting pressure, prey availability, and varying environmental conditions (Kaunda 2001;Minnie et al. 2015). ...
... 2004-2014). Respondents replying 'never' to questions Q1, Q2 and Q3 are presented on the left of each graph predators are removed (Hoffman and O'Riain 2010;Avenant et al. 2016;Minnie et al. 2016;Fehlmann et al. 2017;Drouilly et al. 2018b;Minnie et al. 2018a). Jackal, caracal and baboons are all able to disperse over long distances (Alberts and Altmann 1995;Humphries et al. 2016;Minnie et al. 2018aMinnie et al. , 2018bDrouilly et al. unpublished data) and all three species can navigate a variety of natural and human barriers allowing them to spread through the landscape and recolonise areas from which they were previously extirpated. ...
Article
Conflict between predators and small-livestock farmers is a global phenomenon adversely impacting the preservation of wildlife, the well-being of livestock and human livelihoods. Such conflict is pervasive in the Karoo region of South Africa but its contemporary history and various causes remain poorly understood. In this study, we interviewed 77 small-livestock farmers in the Central Karoo between July 2014 and March 2015 to (1) assess the spatio-temporal distribution and severity of the reported predation problems with the main regional predators of livestock (black-backed jackal, caracal and baboon) and (2) describe the perceived reasons for changes in predator numbers. Farmers reported that serious predation problems have increased since the 1990s for all three predators. Jackal predation appears to have re-emerged, particularly since the 2000s, while baboon predation seems to have escalated rapidly since 2014 for select farmers. Farms with more rugged terrain were more likely to experience serious problems with baboons and caracal but ruggedness did not predict the year of onset of problems. Farmers perceive predator numbers to be increasing and attribute this trend to declining government support for predator management, changes in farming practices and the associated increase in suitable predator habitat, from which they can recolonise commercial farms.
... Numerous control programs in open landscapes have documented little subsequent change in the number of cats detected despite high levels of cat mortality [42,[50][51][52][53]. One plausible explanation for these observations is that there is rapid reinvasion of individuals from surrounding areas, as reported from studies of similar meso-predators [54][55][56], including cats [11,42]. Considering the distances travelled and areas traversed by the cats in this study (Table 1), and other previously recorded long-distance displacements (Table 2), it is obvious that even the extensive areas covered by aerial baiting of cats in our study (650 km 2 of aerial Eradicat ® baiting in the IFRNP and ARKC) are likely to be too small to prevent rapid reinvasion into areas where cat control is undertaken. ...
Article
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Movements that extend beyond the usual space use of an animal have been documented in a range of species and are particularly prevalent in arid areas. We present long-distance movement data on five feral cats (Felis catus) GPS/VHF-collared during two different research projects in arid and semi-arid Australia. We compare these movements with data from other feral cat studies. Over a study period of three months in the Ikara-Flinders Ranges National Park, 4 out of 19 collared cats moved to sites that were 31, 41, 53 and 86 km away. Three of the cats were males, one female; their weight was between 2.1 and 4.1 kg. Two of the cats returned to the area of capture after three and six weeks. During the other study at Arid Recovery, one collared male cat (2.5 kg) was relocated after two years at a distance of 369 km from the area of collar deployment to the relocation area. The movements occurred following three years of record low rainfall. Our results build on the knowledge base of long-distance movements of feral cats reported at arid study sites and support the assertion that landscape-scale cat control programs in arid and semi-arid areas need to be of a sufficiently large scale to avoid rapid reinvasion and to effectively reduce cat density. Locally, cat control strategies need to be adjusted to improve coverage of areas highly used by cats to increase the efficiency of control operations.
... For example, and claimed that in the different Argentinean regions the culpeo has not disappeared due to the existence of a source-sink dynamics. This type of dynamics is common to other canine species populations, such as the European red fox (Vulpes vulpes) in Europe (Rushton et al., 2006), or the black-backed jackal (Canis mesomelas) in South Africa (Minnie et al., 2016), which often renders lethal control efforts useless (Treves et al., 2016;Lozano et al., 2019). ...
Article
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We conducted an extensive review of the existing literature on the culpeo to improve our understanding of its ecology, natural history and conservation, and to identify gaps in current knowledge. For resources published before 1988, we used the synthesis made by Medel and Jaksic (1988). For studies published from 1988 onwards, we carried out a literature searching in the Scopus, Web of Knowledge and Google Scholar databases, considering all of the generic names used to define the species. We found 96 scientific articles. Most of the studies focused on diet, conflicts with the species in livestock areas, and on the use of space and habitat. We found that the description of subspecies is incomplete and that subspecies’ geographic distribution is not well known. There are also few published studies on genetic issues, population dynamics and conservation concerns. It is remarkable that vast regions in South America where culpeos live still lack basic information on the species. Diet studies describe a marked trend towards resource selection at the local level, which supports the view of the culpeo as a facultative trophic specialist. In addition, it has been confirmed that in the high Andes, the culpeo can behave as a top predator and that it is an important seed disperser in arid environments. There is no sufficient information to precisely assess the species’ conservation status in most regions. The species has been listed as "Vulnerable" in Ecuador and Colombia. Direct persecution and habitat transformation are the most critical threats that the species faces in many countries, although other threats such as climate change could also have severe consequences for the culpeo on a global scale.
... In some parts of South Africa, jackals and caracals occupy the trophic position of apex predator given that larger predators, such as lions (Panthera leo) and leopards, have been locally extirpated to enable sheep and goat production (Van Sittert, 1998;Skead, 2007Skead, , 2011. Both jackals and caracals cause substantial impacts to small livestock species and are subject to widespread poisoning, trapping and shooting (Bergman et al., 2013;Minnie et al., 2016b;Drouilly et al., 2018a;du Plessis et al., 2018;Minnie et al., 2018). Warthogs damage fencing infrastructure (facilitating the dispersal of jackals; Minnie et al., 2018), exhibit other nuisance behaviours (Mason, 1982), and have been introduced to many areas outside their historical range (Somers, 1992;Skead, 2007Skead, , 2011. ...
Article
Introducing consumptive and non-consumptive effects into food webs can have profound effects on individuals, populations and communities. This knowledge has led to the deliberate use of predation and/or fear of predation as an emerging technique for controlling wildlife. Many now advocate for the intentional use of large carnivores and livestock guardian dogs as more desirable alternatives to traditional wildlife control approaches like fencing, shooting, trapping, or poisoning. However, there has been very little consideration of the animal welfare implications of deliberately using predation as a wildlife management tool. We assess the animal welfare impacts of using dingoes, leopards and guardian dogs as biocontrol tools against wildlife in Australia and South Africa following the 'Five Domains' model commonly used to assess other wildlife management tools. Application of this model indicates that large carnivores and guardian dogs cause considerable lethal and non-lethal animal welfare impacts to the individual animals they are intended to control. These impacts are likely similar across different predator-prey systems, but are dependent on specific predator-prey combinations; combinations that result in short chases and quick kills will be rated as less harmful than those that result in long chases and protracted kills. Moreover, these impacts are typically rated greater than those caused by traditional wildlife control techniques. The intentional lethal and non-lethal harms caused by large carnivores and guardian dogs should not be ignored or dismissively assumed to be negligible. A greater understanding of the impacts they impose would benefit from empirical studies of the animal welfare outcomes arising from their use in different contexts.
... Administrative borders can be seen as a particular kind of ecological edge between two otherwise contiguous landscape patches, whose characteristics are defined by the specific management actions implemented on each side (Minnie et al. 2016). The risks linked to this type of artificial edge have been more often studied in the context of protected areas and their unprotected surroundings, in which the establishment of source-sink dynamics can potentially jeopardize species persistence and even trigger extinction (Woodroffe & Ginsberg, 1998). ...
Article
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1.Large carnivores are expanding in Europe, and their return is associated with conflicts that often result in policies to regulate their population size through culling. Being wide‐ranging species, their populations are often distributed across several jurisdictions, which may vary in the extent to which they use lethal control. This creates the conditions for the establishment of source‐sink dynamics across borders, which may frustrate the ability of countries to reach their respective management objectives. 2.To explore the consequences of this issue, we constructed a vec‐permutation projection model, applied to the case of wolverines in south‐central Scandinavia, shared between Norway (where they are culled) and Sweden (where they are protected). We evaluated the effect of compensatory immigration on wolverine population growth rates, and if the effect was influenced by the distance to the national border. We assessed to what extent compensatory immigration had an influence on the number of removals needed to keep the population at a given growth rate. 3.In Norway the model estimated a stable trend, whereas in Sweden it produced a 10% annual increase. The effect of compensatory immigration corresponded to a 0.02 reduction in population growth rate in Sweden and to a similar increase in Norway. This effect was stronger closer to the Norwegian‐Swedish border, but weak when moving away from it. An average of 33 wolverines were shot per year in the Norwegian part of the study area. If no compensatory immigration from Sweden had occurred, 28 wolverines shot per year would have been sufficient to achieve the same goal. About 15.5% of all the individuals harvested in Norway between 2005‐2012 were compensated for by immigrants, causing a decrease in population growth rate in Sweden. 4.Synthesis and applications. When a population is transboundary, the consequences of management decisions are also transboundary, even though the political bodies in charge of those decisions, the stakeholders who influence them, and the taxpayers who finance them are not. It is important that managers and citizens be informed that a difference in management goals can reduce the efficiency, and increase the costs, of wildlife management. This article is protected by copyright. All rights reserved.
... These blanket taxonomic-based rules ignore the individual ecology of species and geographic variability, for example assuming all tropical bats are as longlived and reproductively limited as temperate species makes little ecological sense (Russo et al. 2017). Although equating all mammals to rodents is equally fallible, data indicate that even species considered taboo for collecting, such as small carnivores, can handle substantial individual losses and still persist at the population and landscape scale (Minnie et al. 2016, Barychka et al. 2019. ...
Article
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The global environment is faced with growing threats from anthropogenic disturbance, propelling the Earth into a 6th mass extinction. For the world’s mammals, this is reflected in the fact that 25% of species are threatened with some risk of extinction. During this time of species loss and environmental alteration, the world’s natural history museums (NHMs) are uniquely poised to provide novel insight into many aspects of conservation. This review seeks to provide evidence of the importance of NHMs to mammal conservation, how arguments against continued collecting of physical voucher specimens is counterproductive to these efforts, and to identify additional threats to collecting with a particular focus on small mammals across Africa. NHMs contribute unique data for assessing mammal species conservation status through the International Union for Conservation of Nature’s (IUCN) Red List of Threatened species. However, NHMs’ contributions to mammal conservation go well beyond supporting the IUCN Red List, with studies addressing topics such as human impacts, climate change, genetic diversity, disease, physiology, and biodiversity education. Increasing and diverse challenges, both domestic and international, highlight the growing threats facing NHMs, especially in regards to the issue of lethally sampling individuals for the purpose of creating voucher specimens. Such arguments are counterproductive to conservation efforts and tend to reflect the moral opposition of individual researchers than a true threat to conservation. The need for continued collecting of holistic specimens of all taxa across space and time could not be more urgent, especially for underexplored biodiversity hotspots facing extreme threats such as the Afrotropics.
... Heterogeneous control can, for example, induce source-sink dynamics, increasing immigration by individuals from surrounding, no-hunting areas, and effectively increase carnivore population growth rates (Knowlton et al., 1999;Stoner et al., 2006;Schmidt et al., 2017;Minnie et al., 2018). In addition, it is the young, dispersing, individuals that are most likely to move from unmanaged areas to areas where populations are controlled (Minnie et al., 2016). Such young wolves are the ones that typically appear closer to populated areas, and are more likely to attack livestock (Imbert et al., 2016). ...
Article
The recolonization of wolves in European human-dominated landscapes poses a conservation challenge to protect this species and manage conflicts. The question of how humans can co-exist with large carnivores often triggers strong emotions. Here we provide an objective, science-based discussion on possible management approaches. Using existing knowledge on large carnivore management from Europe and other parts of the globe, we develop four potential wolf management scenarios; 1) population control, 2) protection and compensation, 3) fencing, 4) managing behaviour of wolf and man. For each scenario, we discuss its impact on wolf ecology, its prospects of reducing wolf-human conflicts and how it relates to current European legislation. Population control and fencing of local wolf populations are problematic because of their ecological impacts and conflicts with European legislation. In contrast, a no-interference approach does not have these problems but will likely increase human-wolf conflicts. Despite the large challenges in European, human-dominated landscapes, we argue that wolf management must focus on strengthening the separation between humans and wolves by influencing behaviour of wolves and humans on a fine spatio-temporal scale to prevent and reduce conflicts. As separation also demands a sufficiently large wild prey base, we urge restoring natural ungulate populations, to reduce human-wolf conflicts. Mutual avoidance provides the key to success, and is critical to avoid creating the conditions for reinstating wolf persecution as the default policy in Europe.
... This ancient conflict is one of the leading causes of mammalian carnivore declines worldwide and predator control is one of the oldest forms of wildlife management (Berger 2006). While traditionally considered the most economical and effective method, increasing evidence suggests that lethal control can fail to mitigate depredation in the longterm, and at times may even be counterproductive (Minnie et al. 2016, Teichman et al. 2016, Treves et al. 2016, Nattrass et al. 2019. Unselective lethal control methods are also considered by some as inhumane because they can cause suffering, as well as injury and mortality to non-target animals including domestic animals, protected species, and other wildlife (Naughton- Treves & Treves 2005, Rochlitz et al. 2010. ...
Article
The use of livestock guarding dogs (LGDs) has been widely advocated as a responsible tool for reducing livestock predation and conserving wildlife. However, their hidden ecological costs have rarely been investigated. We analysed scats (n = 183) from six LGDs and visited Global Positioning System (GPS) location clusters (n = 352) from nine GPS-collared LGDs to reconstruct their diet and assess impacts on wildlife and livestock in Namaqualand, South Africa. Wild mammals, including 10 native species, and small-livestock were the main secondary foods (i.e. besides dog food pellets). A total of 90% of scats and one third of GPS clusters investigated had associated animal remains. When accompanied by a human attendant, fewer LGD scats contained animal matter (39.9%; of which 32.3% wild mammals and 4.6% livestock), in contrast to scats of LGDs on their own (93.2%; 14.4% wild mammals, 75.4% livestock). Similarly, few clusters of accompanied LGDs included animal remains (5.7%; of which 43.8% wild mammals and 31.3% livestock), whereas unaccompanied dogs clustered frequently at carcasses (92.4%; 16% wild mammals, 74% livestock). While sample sizes were relatively small and some dogs might have scavenged, we emphasize the importance of rigorous training and intensive monitoring of LGDs to correct unwanted predation behaviour and to maximize their ecological and protective benefits.
... In some parts of South Africa, jackals and caracals occupy the trophic position of apex predator given that larger predators, such as lions (Panthera leo) and leopards, have been locally extirpated to enable sheep and goat production (Van Sittert, 1998;Skead, 2007Skead, , 2011. Both jackals and caracals cause substantial impacts to small livestock species and are subject to widespread poisoning, trapping and shooting (Bergman et al., 2013;Minnie et al., 2016b;Drouilly et al., 2018a;du Plessis et al., 2018;Minnie et al., 2018). Warthogs damage fencing infrastructure (facilitating the dispersal of jackals; Minnie et al., 2018), exhibit other nuisance behaviours (Mason, 1982), and have been introduced to many areas outside their historical range (Somers, 1992;Skead, 2007Skead, , 2011. ...
Conference Paper
Introducing consumptive and non-consumptive effects into food webs can have profound effects on individuals, populations and communities. Consequently, the deliberate use of predation and/or fear of predation is an emerging technique for controlling wildlife. Many now advocate for the intentional use of large carnivores and livestock guardian dogs as more desirable alternatives to traditional wildlife control approaches like fencing, shooting or trapping. However, there has been little consideration of the animal welfare implications of deliberately using predation as a wildlife management tool. We assess the animal welfare impacts of using dingoes, leopards and guardian dogs as biocontrol tools against wildlife in Australia and South Africa following the ‘Five Domains’ model commonly used to assess other wildlife management tools. Application of this model indicates that large carnivores and guardian dogs cause considerable lethal and non-lethal animal welfare impacts to the animals they are intended to control. These impacts are likely similar across different predator-prey systems, but are dependent on specific predator-prey combinations; combinations that result in short chases and quick kills will be rated as less harmful than those that result in long chases and protracted kills. Moreover, these impacts are typically rated greater than those caused by traditional wildlife control techniques. The intentional lethal and non-lethal harms caused by large carnivores and guardian dogs should not be ignored or assumed to be negligible. A greater understanding of the impacts they impose would benefit from empirical studies of the animal welfare outcomes arising from their use in different contexts.
... Similarly to other mesopredators worldwide (Gompper, 2002;Arnold et al., 2012), jackal and caracal have re-established populations in former ranges after being extirpated. Signs of their expansion are reported more frequently (Marker & Dickman, 2005;Drouilly et al., 2018c) despite sustained lethal management that seeks to reduce their numbers both on farmland (Tensen, Drouilly & van Vuuren, 2018) and even in PAs (Minnie, Gaylard & Kerley, 2016). Although our results remain preliminary due to the relatively low number of GLCs we were able to investigate, we provide clear evidence that mesopredators kill and consume livestock (presence of typical bite marks notably) but are also able to scavenge, albeit to a lesser extent. ...
Article
Studying the feeding ecology of mesopredators living on or adjacent to farmland is important as livestock predation fuels conflict between farmers and predators and between diverse stakeholders on how to best manage this conflict. Most dietary studies on elusive and heavily persecuted predators rely on indirect methods such as scat analysis, because direct observations of predation events are rare. Consequently, the proportion of livestock and other prey that was actively hunted vs.scavenged remains largely unknown. We used data from global positioning system collars affixed to black-backed jackal (Canis mesomelas) and caracal (Caracal caracal) to locate potential feeding sites on farmland and a protected area and to attempt to determine whether prey had been killed or scavenged. We compareddietary estimates from prey items found at global positioning system location clusters (GLCs) with those obtained from scat analysis and investigated whether GLC analysis is a suitable method to determine mesocarnivore diet. The success rate of finding a kill site when investigating GLCs was significantly higher for caracal than for jackal. Only 16.2% and 4.7% of jackal and caracal GLCs, respectively,were classified as scavenging events. Livestock was the most frequently detected prey in both scats and GLCs on farmland but GLCs provided a higher estimate of sheep biomass than scats. Caracal GLCs revealed prey ranging in size from small to large, whereas jackal GLCs were only for medium and large prey categories.Adult male caracals predated significantly more on livestock than females and younger individuals. Collared jackals residing in the protected area never formed GLCs containing livestock remains on neighbouring farms. Together, GLCs and scat analyses provide a more complete understanding of mesopredators feeding ecology on farmland. We recommend that both methods are applied, particularly in regions where livestock predation and lethal management of predators are driving conflict between stakeholders.
... The ecological narrative drew on predator ecology to warn that killing territorial predators can make problems worse for farmers by releasing wild herbivore populations (thereby creating competition for grazing), disrupting predator social systems (thereby enabling younger females to breed) and facilitating compensatory immigration, potentially worsening the level of livestock depredation (Doherty and Ritchie 2017). This view has been supported by South African biological evidence suggesting that jackals are younger and have larger litters on farms, where they are heavily persecuted, than in nature reserves (Minnie et al. 2016), and that heterogeneous anthropogenic mortality induced source-sink dynamics via compensatory immigration (Minnie et al. 2018). Farmers, however, pointed out that lethal control worked in the past and that as predator numbers are a positive function of food supply, co-existing with predators on extensive livestock farms is not a stable or sustainable solution Conradie 2015, Nattrass et al. 2017, in press). ...
Article
Populations of adaptable mesopredators are expanding globally where passive rewilding and natural recolonization are taking place, increasing the risk of conflict with remaining livestock farmers. We analysed data from two social surveys of farmers in the Karoo, South Africa, where black-backed jackals (Canis mesomelas) and caracals (Caracal caracal) have re-emerged as a threat to sheep farms in the context of falling agricultural employment and the expansion of natural areas. We show that irrespective of measurement approach, lethal control of mesopredators in this fragmented socio-economic landscape was associated with increased livestock losses the following year. Terrain ruggedness was positively, and number of farmworkers negatively, associated with livestock losses. Our study provides further evidence that lethal control of mesopredators in this context is probably counter-productive and supports calls to develop, share and financially support a range of non-lethal methods to protect livestock, especially where natural recolonization of mesopredators is occurring. A graphical abstract can be found in Electronic supplementary material.
... One of the components likely to vary among different situations with different operators is the impact of predator culling on local predator density [5]. A common perception is that culled predators are rapidly replaced through immigration, and this is used to argue both the futility of predator control, and its difficulty and importance [6][7][8][9]. With few exceptions (e.g. ...
Article
Full-text available
Lethal control is widely employed to suppress the numbers of target wildlife species within restricted management areas. The success of such measures is expected to vary with local circumstances affecting rates of removal and replacement. There is a need both to evaluate success in individual cases and to understand variability and its causes. In Britain, red fox (Vulpes vulpes) populations are culled within the confines of shooting estates to benefit game and wildlife prey species. We developed a Bayesian state-space model for within-year fox population dynamics within such restricted areas and fitted it to data on culling effort and success obtained from gamekeepers on 22 shooting estates of 2 to 36 km². We used informative priors for key population processes—immigration, cub recruitment and non-culling mortality–that could not be quantified in the field. Using simulated datasets we showed that the model reliably estimated fox density and demographic parameters, and we showed that conclusions drawn from real data were robust to alternative model assumptions. All estates achieved suppression of the fox population, with pre-breeding fox density on average 47% (range 20%–90%) of estimated carrying capacity. As expected, the number of foxes killed was a poor indicator of effectiveness. Estimated rates of immigration were variable among estates, but in most cases indicated rapid replacement of culled foxes so that intensive culling efforts were required to maintain low fox densities. Due to this short-term impact, control effort focussed on the spring and summer period may be essential to achieve management goals for prey species. During the critical March-July breeding period, mean fox densities on all estates were suppressed below carrying capacity, and some maintained consistently low fox densities throughout this period. A similar model will be useful in other situations to quantify the effectiveness of lethal control on restricted areas.
... Harris and Smith (1987) documented that foxes maintained productivity by reducing the proportion of non-breeding vixens in response to London fox control operations, rather than by altering litter size. Likewise, it was found in a more recent study of black-backed jackals C. mesomelas that the average litter size of females did not increase to compensate for higher mortality, but that it was compensated for by increasing the pregnancy rate and litter size of young individuals, thereby increasing the reproductive output (Minnie et al. 2016). ...
Article
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A decline in the Danish population of red foxes Vulpes vulpes due to an outbreak of canine distemper (CDV) in 2012 gave us the opportunity to test the hypothesis that the reproductive performance of foxes increases when the population density declines. The reproductive performance of 280 female foxes from two periods (mainly shot or road killed) in 1997-2000 and 2012-16, were compared. Game Bag Records of Jutland (GBRJ) were used as an estimate of population density. After a drop in GBRJ in 2013 due to the CDV epidemic, the mean litter size (based on dark placental scars from partum to oestrus) became significantly larger than in previous years; F=4.3, p>0.03, Hc=8.1, p<0.02. In 2015-2016, after population decline the mean litter size was 8.2 (±2.5 SD) and in the breeding seasons before population decline in 1997-1999 and 2012-2013 the mean litter size was 5.6 (±2.1 SD) and 5.7 (±2.0 SD), respectively. During the period 1997-1999, barrenness was relatively high especially in yearlings, and the reproducing yearling foxes made up only 6% of the breeding females compared to 2012-13 and 2015-16 where breeding yearling females made up 53% and 61%, respectively. Age related differences in litter size and productivity were found in years with a relatively high population density, when older females in their third and fourth breeding seasons had the largest litter sizes and highest productivity. This was in contrast to the years with low population size, when no age-related reproduction was found, and when young females had relatively large litter sizes and high productivity. Rump fat thickness (RFT) of the breeding females was significantly higher in breeding females than in barren females, and the RFT was positively correlated to the number of embryos (R2=41%). This study confirms that the number of barren females drops, and the proportion of yearling females and litter size increase with reduced population density. Hence, culling or epidemics in fox populations increase production, most probably due to reduced competition among foxes, but will not change population size permanently. The present level of culling and traditional hunting in Denmark has no long-term effect on population size.
... The integrated approach elucidated caracal use of smaller prey items that were likely to be missed by GPS cluster investigations and overestimated using scat analysis alone. Caracals are frequent sources of human-wildlife conflict (Inskip and Zimmermann 2009;Minnie et al. 2016;Drouilly et al. 2017Drouilly et al. , 2019. In our urban system, they are persecuted for predating pets and domestic fowl. ...
Article
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Urbanisation radically changes habitats and alters available resources. Populations of large, highly mobile species are often extirpated at the urban-wildland interface, while species like mesocarnivores may thrive by capitalising on changes in prey abundance. We investigated the diet of the caracal (Caracal caracal), a medium-sized felid inhabiting patchy natural habitat isolated within the dense urban matrix of South Africa’s second largest city, Cape Town. We systematically integrated two classic dietary methods (scat and GPS clusters) by accounting for gut transit times. As part of a larger caracal ecology study, we GPS-collared 26 individuals over a two-year period (2014–2016) to generate coarse (3-hour) and fine-scale (20-minute) GPS movement data. Using the movement data, we investigated 677 GPS-clusters for prey remains. We collected 654 scats, half of which were found at GPS-clusters and were linked with the individual sampled. By systematically correcting for a range of gut transit times, we determined whether scat at cluster sites was from the same or an earlier feeding event, thereby increasing the overall detection of feeding events by > 50%. Avian prey dominated GPS cluster findings while micromammals were overwhelmingly represented in scat. Although > 40% of feeding events occurred within 200 meters of the urban edge, caracals largely preyed on native species. Our findings have implications for understanding the ability of some species to persist in the face of rapid environmental change, human-wildlife conflict, pathogen transmission, and bioaccumulation of pesticides. Further, this approach could be incorporated into studies that estimate foraging-explicit resource selection and habitat preference.
... The parklands are more complex in habitat structure than prairie ecosystems and effective predator removal is challenging when conducted at small, widely distributed plots across a productive landscape that supports many predator species [89]. The Alberta parklands may be more vulnerable to the creation of a source-sink system where non-managed areas provide source populations for immigration into predator-removal areas [36,90]. Lieury et al. [91] suggested that immigration would quickly negate the effects of reducing red foxes at scales less than 10 km 2 , and that spring culling is more conducive to compensatory immigration than post-dispersal culling. ...
Article
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Nest survival is most limited by nest predation, which often is increased by anthropogenic causes including habitat fragmentation, mesopredator release and predator subsidies. In mallards and other upland-nesting duck species in the North American prairies, the rate of nest survival is the vital rate most influential to population dynamics, with 15%-20% survival required for maintenance of stable populations. Predator removal during the nesting season has increased duck nest survival on township-sized (9324 ha) areas of agricultural ecosystems in eastern locations of the prairie pothole region (PPR). However, predator removal has not been evaluated in western parkland habitats of the PPR where three-dimensional structure of vegetation is considerably greater. During 2015-2017, we evaluated nest survival on control and predator-removal plots at two study areas in the parklands of central Alberta, Canada. In the second year of the study, we transposed predator removal to control for habitat effects. Estimates of 34-day nest survival did not significantly differ between trapped (x = 20.9%, 95% CI = 13.2%-33.7%) and control (x = 17.8%, 95% CI = 10.5%-30.0%) plots in any year. We do not recommend predator removal be continued in Alberta parklands due to its ineffectiveness at improving duck nest survival at the local scale.
... Recent population expansions of coyotes and golden jackals [6,87] have increased the potential for interactions among these carnivores, including interspecific killing by wolves. This will likely increase the value of ecosystem services provided by wolves in controlling mesopredator populations, especially since traditional approaches of limiting mesopredator abundance by shooting and other forms of lethal control suffer from low effectiveness and low social acceptance [88,89]. Improved appreciation of interspecific killing of carnivores as an important ecological role and service provided by wolves could benefit their conservation if used to raise awareness and to promote greater tolerance towards this top predator. ...
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... Whilst commonly used to protect livestock, lethal predator control is often expensive and not always successful (McManus et al. 2015, Moreira-Arce et al. 2018, Bruns et al. 2020, unless targeting "problem animals" (Swan et al. 2017). For some species, particularly mesopredators, the efforts of lethal control are sometimes offset by compensatory processes such as increased reproduction and immigration (Minnie et al. 2016), and can even result in an increase in livestock The ecological effects of livestock guarding dogs (LGDs) on target and non-target wildlife Bethany R. SMITH * , Richard W. YARNELL, Antonio UZAL and Katherine WHITEHOUSE-TEDD depredation (Nattrass et al. 2020). Several forms of lethal control, such as poisoning and some forms of trapping, are also indiscriminate (Ogada 2014). ...
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Population dynamics and life-history evolution depend heavily on fecundity, which, in the coyote (Canis latrans), can vary substantially according to environmental conditions. Although well studied in the central part of its range, little is known about coyote reproduction in the Mediterranean climates associated with Pacific-coastal North America. I used postmortem examinations of 441 coyotes collected throughout central California to investigate reproduction, including age-specific fecundity, breeding synchrony and seasonality, and relationship to nutritional condition. Reproductive parameters did not vary significantly among sampling locations. Overall, numbers of corpora lutea averaged 6.9 (range ¼ 4–11) and litter size (based on fetuses or placental scars) averaged 6.6 (range ¼ 1–12) among postpartum females. The number of corpora lutea increased with maternal age, and litter size also increased with age to 6 years but decreased in older females. Most (77%) adult females became pregnant and 13% of 1st-year females became pregnant. During January–March, 96% of adult males and 68% of 1st-year males had reproductive testes. Reproductive signs in both sexes occurred 3–4 weeks later in 1st-year coyotes than in adults. Parturition dates, which decreased with increasing maternal age, ranged from 9 March to 7 May, indicating that estrus occurred from early January to late March. Of 1st-year coyotes, reproductive individuals were larger during the breeding season and had higher marrow fat indexes than nonreproductive ones (both sexes). After the breeding season, 1st-year females that did not breed (become pregnant) had similar body mass to 1st-year and adult coyotes that did breed, and adult females that did not breed were larger than the others but similar to the weight of breeders during the breeding season. Thus, whether yearlings attained breeding condition apparently depended on their nutritional condition. Adult fecundity estimates were among the highest reported for coyotes. Population dynamics and life-history evolution depend heavily on fecundity. Fecundity of coyotes (Canis latrans) is highly variable, even relative to most other canids, depending on exploitation (Knowlton 1972), food resources (Clark 1972; Todd and Keith 1983; Todd et al. 1981; Windberg 1995), and possibly ambient stress levels (Hartley et al. 1994). The ability to compensate via reproduction for increased mortality is a widely recognized implication for population dynamics (Connolly and Longhurst 1975; Knowlton 1972). The high variability in fecundity also results in an unusually wide range of life-history strategies for coyotes, which resemble r-strategists (high productivity and short life span) in some situations and K-strategists (low productivity and long life span) in others (Pianka 1970). Although numerous studies have recorded reproductive data on coyotes from the central part of their range (e.g., Clark 1972; Todd and Keith 1983; Todd et al. 1981; Windberg 1995), there is a paucity of such information from coyotes in the Mediterranean climate zone associated with Pacific-coastal North America. Examination of available data suggests that, relative to inland regions of North America, coyotes in Pacific-coastal regions breed earlier in the year and less synchronously (Atkinson and Shackleton 1991; Hamlett 1938; Sacks 1996). These geographic differences likely are environmentally mediated (e.g., by seasonal temperature differences). Because Pacific-coastal North America is itself an environmentally diverse area, regional differences in the timing of coyote reproduction might be expected to occur within this area as well. For this study, I took advantage of the relatively long breeding period of coyotes in California to investigate age-specific differences in seasonal reproduction of females and males and fecundity as well as regional variation of such patterns. I also investigated relationships between reproduction and body condition to explore trade-offs between these parameters.
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