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Providing evidence to improve practice

Action: Provide food/salt lick to divert mammals from roads or railways Terrestrial Mammal Conservation

Key messages

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  • Three studies evaluated the effects of providing food or salt licks to divert mammals from roads. One study was in the USA, one was in Norway and one was a review of studies from across North America and Europe.




  • Behaviour change (1 study): A review of feeding wild ungulates in North America, and Europe found that feeding diverted ungulates away from roads in one of three studies.

Supporting evidence from individual studies


A replicated, controlled study in 1985–1986 along three highways in Utah, USA (Wood & Wolfe 1988) found that intercept feeding reduced mule deer Odocoileus hemionus road deaths along two of three highways in one of two years. In the first year, the numbers of mule deer killed on road sections with intercept feeding (8–19 deer killed) were not significantly different to the numbers killed on those without (14–31). The following year, roads kills were lower on two highway sections with intercept feeding (with feeding: 34–38 deer killed; without: 59–89), but higher with feeding on the third (feeding: 31; without: 13). Feeding stations were closer to this third highway (0.4 km) than to the others (0.8–1.2 km). Road-kill deer were recorded along three highways, within 21–24-km-long sections. Highways were divided into a treatment (feed) and control (no-feed) section of equal length (8.3 or 9.6 km), separated by a shorter buffer zone (4.2 or 4.8 km). Treatment and control sections were swapped in the second year. There were four feeding stations/treatment section. Alfalfa hay, deer pellets and apple mash were provided 1–3 times/3 days from January to mid-March of 1985 and 1986.


A replicated, site comparison study in 1985–2003 along a railway through forest in Hedmark County, Norway (Andreassen et al. 2005) found that intercept feeding stations reduced moose Alces alces collisions with trains. There was an estimated 40% collision reduction following feeding station establishment, equating to six fewer moose collisions/year. Providing intercept feeding stations and clearing vegetation >30cm high from alongside the railway did not significantly further reduce collisions (5% reduction) compared to implementing just one of these treatments. Before providing feeding stations, 2.5 times more moose were killed/km/year within treatment sections compared to comparison sections. Numbers killed/km in treatment sections were fairly constant but casualties increased in comparison sections over the study period. Moose feeding stations were established, in 1995, along a 100-km-long railway section. Feeding stations were in side-valleys, linked to three railway sections (4, 6 and 8 km long). Landowners provided food during the winter, using baled grasses and silage and/or herbs, from when snow accumulated until April–May. Sections without treatments were also monitored (total 49 km long). Moose-train collisions were recorded from July 1985–April 2003.


A review of evidence within studies looking at effects of feeding wild ungulates in North America, Fennoscandia and elsewhere in Europe (Milner et al. 2014) found that diversionary feeding diverted ungulates away from roads in one of three studies. No such effect was found in the other two studies. The review also assessed evidence for supplementary feeding affecting survival and morphological characteristics. In total, the review reported evidence from 101 studies that met predefined criteria from an initial list of 232 papers and reports. Three of these studies investigated the effectiveness of feeding for diverting ungulates away from roads.

Referenced papers

Please cite as:

Littlewood, N.A., Rocha, R., Smith, R.K., Martin, P.A., Lockhart, S.L., Schoonover, R.F., Wilman, E., Bladon, A.J., Sainsbury, K.A., Pimm S. and Sutherland, W.J. (2020) Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.