Low-Cost Forensics Reveal High Rates of Non-lethal Snaring and Shotgun Injuries in Zambia's Large Carnivores

Abstract

The impact of snaring and human-wildlife conflict (HWC) on large carnivore populations is of growing concern, and yet few empirical data are available. Mortality is the metric most often used, but non-lethal injuries that impact fitness are also important threats. However, because non-lethal injuries to wild carnivores are difficult to detect, they have received little study. Using straightforward forensic examination of the skulls of trophy-hunted lions and leopards from Luangwa Valley (LV) and Greater Kafue Ecosystem (GKE), Zambia, we identified non-lethal injuries consisting of snare damage to teeth and shotgun pellets in skulls. Wire snare entanglement can cause permanent, diagnostic damage to carnivore teeth when individuals bite and pull on the wire. Shotguns are used by poachers, as well as during HWCs to drive off carnivores perceived as threats. Carnivores struck by shotgun pellets can suffer non-lethal, but potentially toxic injuries such as pellets embedded in their skulls. Because poaching and HWC are generally more prevalent near human settlements, we predicted a higher incidence of anthropogenic injuries to carnivores in Luangwa where the human population is larger and more concentrated along protected area edges than Kafue. Contrary to expectation, anthropogenic injuries were more prevalent among lions and leopards in Kafue than Luangwa. Notably, definitive evidence of snare entanglement greatly surpassed previous estimates for these regions. Overall, 37% (41 in 112) of adult male lions (29% in Luangwa, 45% in Kafue) and 22% (10 in 45) of adult male leopards (17% in Luangwa, 26% in Kafue) examined had survived being snared at some point in their lifetime. Among adult male lions, 27% (30 in 112) had old shotgun pellet injuries to their skulls. Our procedure of forensic examination of carnivore skulls and teeth, some of which can be applied to live-captured animals, allows for improved detection of cryptic, non-lethal anthropogenic injuries. Further, our methods represent a consistent and economical way to track changes in the frequency of such injuries over time and between regions, thereby providing a direct measure of the effectiveness of conservation programs that seek to reduce poaching and HWC.

Long‐term reproductive costs of snare injuries in a keystone terrestrial by‐catch species

“…This suggests that the direct effect of snaring on population growth rate may outweigh the reduction in reproductive success which we identified in the current study. As the cause of death in adults is often difficult to identify, indirect methods based on analyzing patterns of disappearances of individuals, for example during specific seasons associated with specific spatio-temporal risks, or forensic examinations based on snare damage to teeth (White & Van Valkenburgh, 2022), may prove useful for estimating the direct population-level effects of snaring.…”

“…Due to their unselective nature, snares also capture non-target species, including predators attracted to carcasses in snare lines , which results in substantial bycatch (Hofer, East & Campbell, 1993;Becker et al, 2013). For instance, a recent study revealed a high proportion of non-lethal snare injuries in several carnivore species in Zambia, with evidence of snare entanglement greatly surpassing previous estimates for these regions (White & Van Valkenburgh, 2022).…”

Post-Mortem Dental Profile as a Powerful Tool in Animal Forensic Investigations—A Review

“…There have been extensive studies of some forms of ‘human-induced’ damage to animals; for example, non-accidental injury caused to dogs and cats [ 9 , 10 ], the effects of traps and snares [ 11 , 12 ], poisoning [ 13 , 14 ], and shooting on wildlife [ 12 , 15 ]. Death, injury, health concerns, pain, or distress may result from most of the examples cited above but the implications may differ depending on the species and the circumstances surrounding the attack [ 2 , 16 ].…”

Persistent Illegal Hunting of Wildlife in an African Landscape: Insights from a Study in the Luangwa Valley, Zambia

“…The annual elephant mortalities due to illegal hunting in the Luangwa Valley have remained highest in the last two decades among wildlife landscapes in the country [31]. Furthermore, other studies in the Luangwa Valley have reported that high levels of illegal hunting by snaring had increased mortality rates and disturbed population structures of wild animals [28][29][30]36]. The pervasive and persistent illegal hunting by snaring is probably indicative of prevalent local community involvement in poaching, inadequate local community support for conservation and ineffective available measures for addressing poaching by snaring [28,37].…”