Effects of humans and large carnivores on the survival of blackbacked jackals

Effects of humans and large carnivores on the survival of blackbacked jackals

Kamler, J.F., Loveridge, A.J., O’Donnell, H., Macdonald, D.W.

African Journal of Ecology (2020).

INTRODUCTION
The black-backed jackal (Canis mesomelas), hereafter referred to as jackal, is a common mesocarnivore throughout southern and eastern Africa. This species is a generalist omnivore, and research has shown it is very adaptable to different ecosystems, including both natural and anthropogenically modified habitats (Minnie, Avenant, et al., 2016). Historically, they occurred in ecosystems dominated by up to six species of large (>20 kg) carnivores, along with several other mesocarnivores. Under such natural conditions, jackals typically feed on prey ranging from small rodents to small antelope and scavenge on large carnivore kills (Minnie,Avenant, et al., 2016; Skinner & Chimimba, 2005). However, most of the arable land in South Africa has been transformed into agricultural farms and extensive livestock farms, and large carnivores
have been extirpated over most of the country (van Sittert, 1998). Under such human-dominated conditions, jackals appear to thrive, and they have become the dominant predator on farmland throughout most of South Africa (Klare, Kamler, Stenkewitz, & Macdonald, 2010; Minnie, Avenant, Drouilly, & Samuels, 2018; Minnie, Avenant, et al., 2016). Consequently, jackals prey heavily on ungulates in game farms (Klare et al., 2010), and prey heavily on sheep on livestock farms (Kamler, Klare, & Macdonald, 2012; Minnie, Avenant, et al., 2018). In response, human persecution of jackals typically is high on farmland and game farms, and jackal control activities are a standard management practice on most farms (Drouilly, Nattrass, & O’Riain, 2018; Kamler, Stenkewitz, & Macdonald, 2013; Minnie, Avenant, et al., 2016; Minnie, Zalewski,
Zalewska, & Kerley, 2018). 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.For example, jackals have reportedly been killed or consumed by lions (Panthera leo; Schaller, 1972; Stander, 1992), spotted hyaenas (Crocuta crocuta; van Lawick & van Lawick-Goodall, 1970), brown hyaenas (Hyaena brunnea; Mills, 1982), leopards (P. pardus; Schaller, 1972; Estes, 1991), cheetahs (Acinonyx jubatus; Hayward, Hofmeyr, O’Brien, & Kerley, 2006) 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.