Provide diversionary feeding for predators
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Predators can limit population sizes of prey species. Changes in habitat or land management can lead to increases in predator populations, which might negatively affect prey. Removing or controlling predators, especially native predators, for the benefit of their wild prey species can be a controversial management strategy. Nonetheless, there is potential for reduced predator activities to lead to increases in the abundance, survival or reproductive success of prey species. Supplementary feeding of predators may be proposed as an alternative strategy that may be regarded as being more acceptable than removal or lethal control.
Supporting evidence from individual studies
A controlled, before-and-after study in 2008–2011 in four boreal forest, peatland and heath sites in Newfoundland, Canada (Lewis et al. 2017) found that diversionary feeding of predators appeared to increase woodland caribou Rangifer tarandus calf survival. However, the significance of the intervention was not explicitly tested. Caribou calf survival during diversionary feeding (70-day survival: 23%; 182-day survival: 14%) appeared to be higher than before diversionary feeding commenced (70-day survival: 9%; 182-day survival: 7%) though there was high variability in these data. Survival rates across these two periods at sites without diversionary feeding were stable (70-day survival: 56–59%; 182-day survival: 41–47%). Supplementary food was mostly taken by American black bears Ursus americanus which, along with coyotes Canis latrans, were the most frequent confirmed predators of caribou calves. At one site, 500-kg bags of bakery waste were distributed in a grid of 4.5 × 4.3-km quadrats, covering most of the caribou calving area. Food was provided from before 25 May until mid-July in 2010 and 2011 and was replenished weekly as required. In 2011, food was supplemented with beaver Castor canadensis carcasses. Three other caribou calving sites received no supplementary food. Across all sites, 313 caribou calves were radio-collared in late May to early June of 2008–2011, when 1–5 days old, and were monitored by radio-tracking through to November.Study and other actions tested