Learning from science and history about black-backed jackals Canis mesomelas and their conflict with sheep farmers in South Africa

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.     

Prey of coastal black-backed jackal Canis mesomelas (Mammalia: Canidae) in the Skeleton Coast Park, Namibia

Remains of prey of black-backed jackal Canis mesomelas from 13 jackal middens situated within 25 m of the beach, which provides the most regular source of food, and one 1.3 km inland in the Skeleton Coast Park, Namibia, were examined. Middens accumulate on small sand hummocks which provide shelter from prevailing harsh environmental conditions. Canis mesomelas is shown to rely on marine resources. A total of 30 taxa was recorded. Birds were the most common prey individuals represented in the combined samples (68%), followed by mammals (17%) and fish (15%). One invertebrate was recorded. At the inland site, which is located at a colony of whitebreasted cormorants Phalacrocorax carbo , this species alone formed 78% of the total individuals. Surveys were conducted to determine the extent to which C. mesomelas is unselective in scavenging beached seabird carcasses and the results were compared with data on roosting habits. There was good correlation between both these sets of data and the contents of the jackal middens, thereby indicating that C. mesomelas is unselective in its foraging/scavenging. The drop in the jackass penguin population was also evident when middens of different ages were compared. It was shown that the data from jackal middens provide an index of seabird mortality which reflects changes in the oceanic and climatic conditions which affect fish populations. Regular monitoring of jackal middens may provide an easily accessible source of information on long- and short-term changes in fish stocks.     

Social organization,home ranges,and extraterritorial forays of black-backed jackals

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.     

Landowners’ perspectives of black‐backed jackals (Canis mesomelas) on farmlands in KwaZulu‐Natal,South Africa

Despite continued efforts to eradicate black‐backed jackals (Canis mesomelas), they are considered an abundant mesopredator on agricultural land across South Africa, resulting in ongoing human–wildlife conflict and concern for farmers and wildlife managers. We conducted a questionnaire survey and semi‐formal interviews with farmers throughout KwaZulu‐Natal, examining farmers’ livestock husbandry, land‐use changes and perspectives towards jackals as a perceived threat to livestock. Many (75%) respondents acknowledged expanding agricultural activities on their farmlands since the onset of their farming careers. However, the perception was that these changes placed little pressure on mesopredators as farmers reported frequent daily (25%) and weekly (31%) sightings of jackal, and regular predation on livestock (72%). Some landowners (31%) reported between one and five livestock losses annually and suggest that mitigation strategies to prevent livestock losses are in place. Farmers suggested the increasing intensity in agricultural practices provided a greater food source for jackals allowing them to thrive in expanding agricultural conditions and, in some circumstances, farmers admitted to possibly being a cause through poor disposal techniques for dead animals. Feedback from farmers emphasized the importance of having collaboration between farmers to control jackal predation and reduce human–wildlife conflict.     

Current status and distribution of golden jackals Canis aureus in Europe

• 1 The golden jackal Canis aureus is one of the most widespread canid species with a range covering areas of central, eastern and southern Europe, northern Africa and parts of Asia. Distribution of the golden jackal in Europe has been dynamic, including dramatic declines (until the 1960s), recovery (1960s and 1970s) and expansion (from the early 1980s onwards).
• 2 We present up‐to‐date information on golden jackal status in Europe and range expansion.
• 3 For data collection we reviewed the scientific literature and contacted scientists from the relevant countries. We distinguished between vagrant animals and established populations.
• 4 In the last decade, there has been an increase in jackal records in areas where the species has not been reported before. Increased presence is recorded northwards and westwards of the distribution range of the golden jackal, specifically in Hungary, Serbia and Slovakia. In Austria, the first case of reproduction was confirmed in 2007; reproduction has also recently been reported in Italy.
• 5 Results indicate an ongoing expansion in Europe's jackal population, with a particular spread of the Balkan populations towards central Europe. Although there are numerous reports of sightings, only few originate from confirmed sources and in many areas status is unknown or vague. There is a general lack of ecological data and almost no information on ecological consequences associated with the golden jackal expansion.

     

Resource dispersion, territory size and group size of black-backed jackals on a desert coast

We studied the relationship between resource—food patch—richness and dispersion on group and territory size of black-backed jackals Canis mesomelas in the Namib Desert. Along beaches where food patches are mostly small, widely separated jackal group sizes are small, and territories are narrow and extremely elongated. Where food patches are rich, fairly clumped and also heterogeneous, group sizes are large and territory sizes small. At a superabundant and highly clumped food source—a large seal rookery—group sizes are large, and territoriality is absent. Although jackals feed at the coast and den nearby, individuals move linearly far inland along well-defined footpaths. The marked climatic gradient from the cold coast inland—a drop in wind speed and rise in effective temperature T _e – and use of particular paths by different groups—strongly suggests that these movements are for thermoregulatory reasons only.     

Scale-free dynamics in the movement patterns of jackals

Using conventional radio-tracking techniques employed by field ecologists, evidence for scale-free (fractal) behaviour in the foraging trajectories of a species of African jackal is presented. It is believed that the particular form of foraging strategy observed here is a response by the jackal to its need to locate resources in an unpredictable environment. The methods used in this study are completely general and can be applied to other radio-tracked species, thus beginning a systematic investigation of foraging strategies in mammals.     

Factors affecting invertase activity in soils

Summary The rate of reducing sugars released through invertase activity exhibited a buffer pH optimum of 5.0. Generally, the decline in invertase activity in its pH-profile near the optimal pH range was due to a reversible reaction that involved ionization or deionization of the functional groups in the active centre of the protein, but under highly acidic or alkaline conditions (pH<4 to >9) the reduced activity appears to be due to irreversible inactivation of the enzyme. The dependence of the reaction on the amount of enzyme present was linear up to 3 g of soil. By varying the substrate concentration, it was found that the reaction rate of this enzyme approached zero-order kinetics when 145mM of sucrose solution was added to soils. Application of three linear transformations of the Michaelis-Menten equation indicated that the apparent K_m constants varied among the soils studied, but the results obtained by the three plots were similar. By using the Lineweaver-Burk plot, the K_m values in five soils ranged from 16.3 to 42.1 (avg.=24.5) mM and V_max values ranged from 1.98 to 7.37 mg of reducing sugars released/g of soil/24 h. The optimum temperature for invertase activity in soils was observed at 50°C and denaturation of the enzyme began at 55°C. The activation energy (E_a) and enthalpy of activation (H^*) values for invertase activity, expressed in kJ/mole, ranged from 6.1 to 43.1 and 3.5 to 40.5, respectively. The Q₁₀ values for the invertase reaction in soils with a temperature range to 10 to 50°C ranged from 1.08 to 1.96. Under standerd conditions, the accumulation of reducing sugars was linear with time up to 48 h. Among the various pretreatments that affected invertase activity in soils, toluene, TCA, and PMA inhibited the enzyme by an average of 19, 54, and 11%, respectively. Steam-sterilization essentially destroyed soil invertase.