Abstract
Human–predator conflicts are globally widespread, and effective interventions are essential to protect human assets from predator attacks. As effectiveness also has a temporal dimension, it is of importance to know how long interventions remain most effective and to determine time thresholds at which effectiveness begins to decrease. To address this, we conducted a systematic review of the temporal changes in the effectiveness of non-invasive interventions against terrestrial mammalian predators, defining a temporal trend line of effectiveness for each published case. We found only 26 cases from 14 publications, mainly referring to electric fences (n = 7 cases) and deterrents (n = 7 cases). We found electric fences and calving control to remain highly effective for the longest time, reducing damage by 100% for periods between three months and 3 years. The effectiveness of acoustical and light deterrents as well as guarding animals eroded quite fast after one to five months. Supplemental feeding was found to be counter-productive by increasing damage over time instead of reducing it. We stress that it is vital to make monitoring a routine requirement for all intervention applications and suggest to standardize periods of time over which monitoring can produce meaningful and affordable information.
Highlights
Livestock killing by predators, known as depredation, and nuisance behaviour in human environments often lead to conflicts and retaliatory killing of predators [1,2,3,4,5]
We checked how effectiveness trend lines fitted to the scenarios of intervention effectiveness change over time. We suggested these scenarios to depend on how fast predators can adapt and habituate to interventions: (i) interventions causing fast habituation—the % of damage reduction decreases fast as predators become habituated and keep on causing damage; (ii) interventions causing slow habituation—the % of damage reduction stays high for some time at the beginning of intervention application, but predators become habituated and the effectiveness of an intervention goes down; and (iii) interventions causing least habituation—the % of damage reduction is always high or, ideally, maximum (100%) as it is problematic for predators to adapt and get habituated
Many cases dealt with the coyote (Canis latrans; n = 9 cases) and the American black bear (Ursus americanus; n = 5), and fewer cases with the black-backed jackal (Canis mesomelas, n = 3), caracal (Caracal caracal, n = 3), brown bear (Ursus arctos, n = 2), puma (Puma concolor, n = 2), domestic dog (Canis familiaris, n = 2), red fox (Vulpes vulpes, n = 2), grey wolf (Canis lupus, n = 2), polar bear (Ursus maritimus, n = 2), Asiatic black bear (Ursus thibetanus, n = 1), leopard (Panthera pardus, n = 1), Iberian lynx (Lynx pardinus, n = 1) and spotted hyena (Crocuta crocuta, n = 1)
Summary
Known as depredation, and nuisance behaviour in human environments often lead to conflicts and retaliatory killing of predators [1,2,3,4,5]. These conflicts are among the main threats to peaceful coexistence of predators and local livelihoods, so that 61% of 28 species of the world’s large terrestrial predators already face extinction [6] and many rural and suburban communities still experience strong psychological stress and financial losses to predators [3,7,8]. Non-invasive interventions, which exclude animal handling, should be of high priority to counterbalance social disfavour, high financial burdens and generally low effectiveness of lethal (killing, trapping and poisoning) and invasive non-lethal (translocation, sterilization and shock collars) interventions [11]
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