In many countries, feeding wild ungulates is a common practice. The question arises: do we understand completely a supplementary feeding of ungulates in the forest? It seems that this practice is more complex than one might think.
Scientists from the Institute of Nature Conservation (Polish Academy of Sciences), in order to find an answer to that question, designed an interesting experiment, where main goal was to investigate the indirect effects of supplementary feeding on nest predation risk in the Polish Eastern Carpathians (Bieszczady Mountains). They formed the hypothesis that next to the feeding sites, the predators, attracted to ungulates, would also forage for alternative prey nearby, increasing for instance the nest predation risk for ground-nesting birds in the vicinity.
Researchers conducted an experiment in a very smart way in my opinion. They placed artificial nests (N = 120) in feeding and control sites (N = 12) at different distances from the ungulate feeding site. In addition, in three ungulate feeding sites, they installed automatic cameras.
The results were astonishing. It appeared, that the proportion of depredated nests was 30% higher in the vicinity of feeding sites than at control sites. As expected, the probability of a nest being depredated significantly increased with time and at shorter distances from the feeding site.
Researchers recorded in total 13 species of potential groundnest predators at ungulate baiting sites. The most common appeared to be Eurasian jays (Garrulus glandarius), mice and voles (Muroidea), ravens (Corvus corax), brown bears (Ursus arctos), and wild boars (Sus scrofa).
On the other hand, other group of researchers from UK, Denmark, Austria, Canada and Norway, quantified the empirical evidence for whether the intended effects, and hence management goals, of feeding are met. They found, as one could expect, that under certain conditions, the supplementary feeding enhances reproduction and population growth. More interesting, there was a limited evidence of the effectiveness of diversionary feeding on crops, forestry, and natural habitats protection. And here comes one thing, that I have to admit personally I have not been thinking about, that supplementary feeding may help to reduce traffic collisions, especially in places with high traffic.
To the other unintended effects of feeding, researchers included, inter alia, changes to demography, behavior as well as exacerbated risks of disease transmission among ungulates.
Increased ungulate density was mentioned as the main driver behind these unintended effects.
You can find whole articles under links below. Enjoy!
Selva N, Berezowska-Cnota T, Elguero-Claramunt I.2014. Unforeseen Effects of Supplementary Feeding: Ungulate Baiting Sites as Hotspots for Ground-Nest Predation. PLoS ONE 9(3): e90740.
Milner J.M., van Beest F.M., Schmidt K.T., Brook R.K., Storaas T. 2014. To Feed or not to Feed? Evidence of the Intended and Unintended Effects of Feeding Wild Ungulates. The Journal of Wildlife Management 78(8):1322–1334; 2014.