The proximity of rapeseed fields influences levels of forest damage by red deer

Abstract

1. Deer can show transitional use between agricultural fields and forests for foraging and shelter. Such transitional use may affect forest damage as nutrient balancing theory suggests that if deer ingest large amounts of nutrient-rich food, complementary browse, such as bark, may be required to balance the diet.2. We investigated the relationship between the level of red deer Cervus elaphus bark-stripping damage in 68 Norway spruce Picea abies stands and the presence of rapeseed Brassica napus fields -an energy-rich crop preferred by red deer -in the surroundings, hypothesizing that damage increases with decreasing distance to rapeseed fields. We also considered other potentially influencing factors, such as supplemental feeding, alternative forage availability, and deer use of spruce stands as indexed by a pellet group count.3. Spruce stands closer to rapeseed had a significantly higher proportion of damaged stems. The increased level of bark-stripping damage was not explained by a higher stand use of deer closer to rapeseed fields, indicating that deer increase their consumption of bark in order to balance their diet. Similarly, spruce stands closer to supplemental feeding stations had significantly higher damage levels. 4. In line with earlier findings, damage levels were negatively related to the amount of available browse in the forest. This emphasizes the importance of alternative forage for reducing the damage risk in forest plantations. 5. Our study shows that the availability of fields with nutrient-rich food, such as rapeseed, as well as supplemental feeding needs to be considered when predicting the level of forest damage. With a high availability of nutrient-rich food in the vicinity of forest stands, a higher damage level can be expected and counteractions could be taken such as increased disturbance, harvest or changed choice of both crop and supplemental feed types. These actions may also be combined with a push-pull strategy where the deer are steered to disturbance-free zones insensitive to damage and with alternative forage. The importance of alternative forage availability onThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Drivers of ungulate behavior in the context of human-wildlife conflicts : The effects of food, fear and temperature on ungulate landscape use and impacts

“…According to the nutritional balancing hypothesis (Simpson & Raubenheimer, 2012), ungulates feeding on nutrient rich crops may need to increase their intake of fibrous plants (Felton et al, 2016). Similar findings have been reported by (Jarnemo et al, 2022), showing that bark stripping by red deer on spruce was higher in forest patches close to a nutrient dense crop and that the effect of proximity of crops was not due to an increased red deer density in those forest patches. The influence of nutritional demands may also explain how crop type shaped the effect of distance from the field on browsing pressure, where browsing pressure declined more strongly with increasing distance around oat fields compared to grass fields.…”

“…Furthermore, forage availability inside the forest patch itself was also important in determining damage, with decreasing browsing pressure in areas with a high availability of tree saplings that are known to be important forage items for all cervid species (Spitzer, 2019). This result goes in line with several other studies (Jarnemo et al, 2022;Ball & Dahlgren, 2002) and lends further support to the findings regarding the importance of alternative forage in production forests to mitigate negative impact by ungulates. Furthermore, it suggests that features of the foodscape are important on different scales, both in the surrounding landscape across land use borders, as well on a more local scale inside the patch where damage is occurring (Felton et al, 2022).…”