Search

Spatial patterns of and competition for resources by territorial carnivores are typically explained by two hypotheses: 1) the territorial defence hypothesis and 2) the searching efficiency hypothesis.According to the territorial defence hypothesis, when food resources are abundant, carnivore densities will be high and home ranges small. In addition, carnivores can maximise their necessary energy intake with minimal territorial defence. At medium resource levels, larger ranges will be needed, and it will become more economically beneficial to defend resources against a lower density of competitors. At low resource levels, carnivore densities will be low and home ranges large, but resources will be too scarce to make it beneficial to defend such large territories. Thus, home range overlap will be minimal at intermediate carnivore densities.According to the searching efficiency hypothesis, there is a cost to knowing a home range. Larger areas are harder to learn and easier to forget, so carnivores constantly need to keep their cognitive map updated by regularly revisiting parts of their home ranges. Consequently, when resources are scarce, carnivores require larger home ranges to acquire sufficient food. These larger home ranges lead to more overlap among individuals' ranges, so that overlap in home ranges is largest when food availability is the lowest. Since conspecific density is low when food availability is low, this hypothesis predicts that overlap is largest when densities are the lowest.We measured home range overlap and used a novel method to compare intraspecific home range overlaps for lions Panthera leo (n = 149) and leopards Panthera pardus (n = 111) in Africa. We estimated home range sizes from telemetry location data and gathered carnivore density data from the literature.Our results did not support the territorial defence hypothesis for either species. Lion prides increased their home range overlap at conspecific lower densities whereas leopards did not. Lion pride changes in overlap were primarily due to increases in group size at lower densities. By contrast, the unique dispersal strategies of leopards led to reduced overlap at lower densities. However, when human‐caused mortality was higher, leopards increased their home range overlap. Although lions and leopards are territorial, their territorial behaviour was less important than the acquisition of food in determining their space use. Such information is crucial for the future conservation of these two iconic African carnivores. [ABSTRACT FROM AUTHOR]

Habitat heterogeneity is a key driver of the diversity and distribution of species. African savannas are experiencing changes in their vegetation structure causing shifts towards increased woody plant cover, which results in vegetation structure homogenization. Given the impact that increasing woody plant cover has on patterns of animal use, resource managers across Africa are implementing habitat management practices that are intended to reduce woody plant cover. To understand the ecological implications of various habitat management practices on arthropod and bird communities, we leveraged large‐scale tree clearing and subsequent mowing in an African savanna to understand how changes in both the herbaceous layer and woody plant cover (i.e., structural heterogeneity) may shape arthropod and bird communities at the local scale. We focused on four replicated treatments: (1) annual summer mow, (2) annual winter mow, (3) >5 years since last mow (rest), and (4) an adjacent unmanipulated savanna to act as a control. We found that the mowing treatments significantly influenced vegetation structure both with respect to tree density and herbaceous layer. Both arthropod and bird community composition varied across treatments. Grass biomass was the best predictor of arthropod richness and abundance, with arthropods selecting for areas with high biomass. Insectivorous bird richness and abundance was driven by tree density (i.e., perching locations) and not arthropod abundance. Our results suggest that vegetation management practices contribute to habitat heterogeneity at the landscape scale and increase bird species richness through species turnover. However, we caution that if a single vegetation management practice dominates the landscape, it is plausible that it could lead to the simplification of the avian community. [ABSTRACT FROM AUTHOR]

Context: Mesopredators experience top down pressure from apex predators, which may lead to behavioural changes such as spatial avoidance to reduce both interference and exploitative competition. However, apex predators may also facilitate mesopredators through the provision of carrion, so mesopredators should respond flexibly to the presence of apex predators. Aims: We aimed to investigate the drivers of black-backed jackal (Canis mesomelas) space use and detection in areas with and without lions (Panthera leo). We predicted that jackal detection and space use will be greater if apex predators facilitate rather than suppress them. Additionally, we predicted that in the absence of lions, the relative abundance of small ungulate species may become important drivers of space use and detection, because jackals can switch from scavenging to hunting. Comparatively, in the presence of lions, larger ungulate species will become important drivers of space use and detection as these species become accessible to jackals through scavenging. Methods: We used camera-trapping surveys, a single-species, single-season occupancy modelling approach, and the assessment of activity patterns to explore how apex predators influence the presence and probability of use of different sites in the Eastern Cape province of South Africa. Key results: Apex predators both positively and negatively affected the detection of jackals, indicating that these mesopredators show behavioural flexibility at the individual site level. There was high overlap between jackal activity patterns in the presence and absence of lions; however, at one site with lions, jackal activity did not peak at night as observed at other sites. Conclusions: Our results indicate that jackals demonstrate behavioural flexibility in the presence and absence of apex predators. Importantly, our results show that apex predators can both facilitate and suppress mesopredators, and that their behavioural responses are dependent on site-specific factors. Implications: Our findings highlight that sympatric predator behaviours should be based on site-specific behaviours instead of the general patterns observed in more temperate systems. We evaluated the influence of apex predators on the drivers of mesopredator space use and detection in South Africa. Apex predators both positively and negatively affected the detection of black-backed jackals, indicating that these mesopredators show behavioural flexibility at the individual site level. These findings suggest that sympatric predator behaviours should be based on site-specific behaviours instead of general patterns. Photograph by Rebecca Welch. [ABSTRACT FROM AUTHOR]

The Kruger National Park (KNP) is considered an important biodiversity hotspot, with insectivorous bats representing about twenty percent of the total mammalian diversity of South Africa. Historically, 40 bat species have been documented in the northern region of the Park between 1960 and 1990. However, it has been three decades since the last comprehensive assessment. To aid the long-term monitoring of bats within KNP, our study re-surveyed the bat community of northern KNP over two years, incorporated the latest acoustic technologies, compared changes in bat species richness with historical data, and tested the use of an automated classifier for the acoustic data. We captured bats and recorded echolocation calls at 26 sites), between March and October in 2017 and 2018. Kaleidoscope Pro software was used to identify each bat call series recorded. To enhance the accuracy of this tool, a northern KNP-specific classifier was developed. We recorded 27 distinct species during this study, of which 13 were live-captured. The historical data therefore show a much higher richness of bat species within the study area (40 species) than recorded during our study (27 species), although the former were collected over a much longer period of time during numerous collecting trips by staff of the former Transvaal Museum (Ditsong National Museum of Natural History). Total sample effort, environmental effects, biological aspects and overall study limitations likely contributed to the observed differences. The classifier tool had a relatively high percentage accuracy (80%) but manual identification was required to avoid the misidentification of rare species and to detect new species not previously recorded. Future studies should focus more effort on live-capturing, given the high species richness of the region and the limitation of bat detectors to record high frequency and low intensity echolocation calls, which are common in many southern African species. [ABSTRACT FROM AUTHOR]

Livestock guarding dogs (LGDs) have been used for centuries to reduce depredation on livestock and, more recently, to facilitate the conservation of threatened carnivores. Conservation organisations in southern Africa promote the use of Anatolian shepherds as LGDs. However, livestock farmers in Botswana use a variety of breeds for this purpose, including local landrace "Tswana" dogs. Our study sought to test the overall effectiveness of these local breeds as LGDs. Irrespective of breed, all LGDs reduced livestock losses, with 47.9% of farmers experiencing no losses after obtaining a guarding dog. Owners with more LGDs, and LGDs of a single sex, had greater reductions in livestock losses. Anatolian shepherds displayed more behavioural problems than other breeds in our study. The health of LGDs was reliant on them receiving a balanced diet, and owners with fewer dogs reported fewer health issues. Moreover, Tswana guarding dogs were cheaper to purchase and feed than their purebred counterparts. Our results show that local landrace dogs can be considered a cheaper and more practical alternative to purebred LGDs for reducing livestock losses and for mitigating human-wildlife conflict in Botswana. [ABSTRACT FROM AUTHOR]

Context: Managed wild lions (Panthera leo) are lions found in smaller (<1000 km2), fenced protected areas that hold a substantial portion of South Africa's wild lion population. Because the natural population control mechanisms are compromised within these properties, managers must actively control population growth rates. Fecundity control is used by wildlife managers, but long-term, empirical data on the impact and consequences of such interventions in lions are lacking. Aims: The aim of the present study was to assess the effectiveness of two methods of contraception (deslorelin implant and unilateral hysterectomy) in reducing cub recruitment of managed wild lions. Methods: Survey data spanning 14 years from 94 managed wild lions on 19 protected areas were used to evaluate the effectiveness of deslorelin implant treatments and unilateral hysterectomies on population growth rates through mimicking open system cub recruitment. Key results: Deslorelin implants were effective at increasing the age of first reproduction and lengthening inter-birth intervals. There was also an unexpected decrease in litter size. Behavioural side-effects were recorded in 40% of individuals: 19% pride fragmentation; 13% lack of receptiveness towards males; 8% other. The more successive deslorelin implants a lioness had, the more likely it was that weight gain was reported. Unilateral hysterectomy resulted in a decrease in litter size post-surgery, but this was not statistically significant. No behavioural or physiological side-effects were noted after unilateral hysterectomy. Conclusions: Deslorelin treatment was more effective in reducing the reproductive output of managed wild lionesses than unilateral hysterectomy surgery. While more side-effects were associated with deslorelin implants than unilateral hysterectomies, a single deslorelin treatment is currently a good option for fecundity reduction. More research is required on unilateral hysterectomy surgery. Implications: Neither deslorelin implants nor unilateral hysterectomies offer a 'silver bullet' solution for reducing rapid population growth in managed wild lions. Reproductive control should be integrated with other best-practice approaches. African lion growth rates in smaller fenced protected areas are managed to prevent overpopulation. Using historical data, we found that deslorelin implants were more effective at reducing reproductive output than unilateral hysterectomy surgery. However, there were some undesirable side-effects associated with the implants. These findings advance the lion management practices on small fenced reserves; habitats that are becoming more valuable as larger lion populations are threatened across Africa. Photograph by Susan M. Miller. [ABSTRACT FROM AUTHOR]

Using a standard protocol, we conducted vertebrate roadkill surveys in the Greater Mapungubwe Transfrontier Conservation Area (GMTFCA), South Africa, which is a World Heritage Site. A total of 991 roadkill were recorded on the paved roads and 36 roadkill on the unpaved roads. Identifiable roadkill comprised 162 species from 24 orders and 65 families. Ninety-three roadkill could not be identified to species level. Roadkill counts were strongly influenced by road type and season. More roadkill was recorded on the paved than the unpaved roads. Irrespective of road type, the proportion of roadkill was greatest in the hot/wet season (4.3 paved roadkill/km/day paved and 1.3 roadkill/km/day unpaved) and lowest in the cold/dry season (2.0 roadkill/km/day paved and 0.1 roadkill/km/day unpaved). The high numbers of vertebrates identified as roadkill suggests that road traffic has the potential to directly and negatively affect biodiversity conservation in this part of South Africa. We recommend continued roadkill data collection across South Africa to assist with creating an inventory of species most likely to be at risk from roads. This will, in turn, better inform the implementation of potential mitigation measures. [ABSTRACT FROM AUTHOR]

Habitat loss, persecution and population declines have resulted in the restriction of many large carnivores, including cheetahs (Acinonyx jubatus), to fenced reserves. These reserves are often small and the likelihood of interference competition between dominant and subordinate predators is increased, while the possibility of spatial avoidance is reduced. Given artificial space limitations, subordinate predators may reduce competitive interactions along niche axes other than habitat type such as time, coined a 'management-induced niche shift'. We collected data on the activity patterns of male and female cheetahs using continuous follows and satellite GPS collars on two small, fenced reserves in the Eastern Cape Province of South Africa, one with lions (Panthera leo) and one without lions. There was a significant difference in the activity patterns of male and female cheetahs between the two reserves. In the presence of lions, nocturnal activity of cheetahs was greatly reduced, particularly for females. There was a corresponding increase in crepuscular activity for male cheetahs and diurnal activity for female cheetahs. In the context of other studies, our results suggest that space limitation affects cheetah response to lions and provides the first quazi-experimental evidence of a management-induced niche shift. [ABSTRACT FROM AUTHOR]

Reintroductions of African wild dogs (Lycaon pictus) in the KwaZulu-Natal Province, through the managed metapopulation approach, promoted a population expansion from one pack in Hluhluwe-iMfolozi Park in 1997 to nine packs in three reserves by 2009. Consequently, the likelihood of dispersing wild dogs leaving their natal ranges from within fenced reserves also increased. Land outside these reserves could potentially be utilized to expand wild dog distribution and provide connectivity between the geographically isolated subpopulations. We used Maximum Entropy Modelling (Maxent) to characterize habitat niche selection of transient wild dogs outside of resident reserves, and to identify potential dispersal linkages between subpopulations. A habitat suitability model indicated four variables (elevation, land cover, road density and human density) best predicted probability of presence for transient wild dogs. Elevation (AUC > 0.80) and land cover (AUC > 0.75) were the two most influential variables when considered independently. Transient wild dogs preferred lower lying locations (130-330 ma.s.l.) covered by woodland or bushland; habitat indicative of the preferred prey of wild dogs. Considerable habitat exists for subpopulation linkages; however, the majority of wild dog movements between subpopulations required mitigation of potential or real game or livestock losses. Development of formal linkages and wild dog management between subpopulations will require a sustained approach to improving tolerance towards wild dogs, clarity on financial obligations and management responses to pack and prey population dynamics. [ABSTRACT FROM AUTHOR]

Rewilding is a conservation strategy used to restore ecosystems to previous states and can involve the reintroduction of large carnivores into areas from where they had been previously extirpated. Whilst rewilding has been important for ecosystem functioning, it can have negative implications for naïve prey that have had no exposure to the presence of large carnivores. Therefore, understanding prey responses to the reintroduction of predators is crucial for management and conservation. We assessed the effects of reintroduced cheetahs ( Acinonyx jubatus) on the vigilance of two species of naïve prey: the steenbok ( Raphicerus campestris) and the springbok ( Antidorcas marsupialis).We hypothesized that both species would increase their vigilance behaviour post-cheetah reintroduction, but that the steenbok would demonstrate a greater response due to their smaller body size and more solitary nature. To test this, we compared the vigilance of both species before and after the reintroduction of cheetahs. Both species increased vigilance within one year post-cheetah reintroduction, but the steenbok demonstrated a much stronger response with a ~70% increase in the percentage of time spent vigilant post-cheetah reintroduction. Springbok levels of vigilance were lower (~50% increase), which we suggest is a function of body-size and/or grouping behaviour. Importantly,we showthat naïve prey species are able to exhibit a rapid response to the reintroduction of large carnivores.However, the variation in responses highlights the importance of species-level monitoring after large carnivore reintroductions. [ABSTRACT FROM AUTHOR]