Crops - Behavioural adjustments Behavioural adjustments



Diversion

By providing wildlife with alternatives, their need for utilising valuable crops may be reduced.

Three articles have evaluated the effect of providing alternative food or scent marking opportunities to reduce the need for wildlife to cause damage to standing crop. One study from Connecticut, USA, found the provision of scent marking stations for woodchucks (Marmota monax) reduced gnawing damage on apple trees by 4.8 cm2 compared to the control. However, this was not a significant reduction, and when the scent marking station included sodium, the gnawing damage increased by 4.4 cm2 in comparison to the control.

Another study from British Columbia, Canada, made multiple tests of food provisioning for montane voles (Microtus montanus) and meadow voles (Microtus pennsylvanicus) to divert gnawing damage from apple trees. In comparison to the control, providing supplementary feeding in the form of 9 mm thick kiln-dried Douglas fir plywood sticks (5 x 37.5 cm) treated with sucrose on average increased the bark tissues removed from from a tree by 18.4 cm2. Sticks treated with soybean oil on average increased the bark tissues removed per tree by 12.2 cm2 and sticks treated with sorbitol increased the tissues removed per tree by 11.3 cm2. The same study also evaluated the risk of an apple tree being attacked by montane voles, when diversionary feeding was provided. It was found that diversionary feeding in the form of logs composed of Douglas fir bark mixed with wax and soybean oil reduced the risk that an apple tree would suffer vole damage (RR = 0.4) in comparison to the control. In comparison to the control, the risk of an attack was also slightly reduced when voles were provided with logs composed of Douglas fir bark mixed with wax and dehydrated apple powder (RR = 0.7), but barely when provided with logs composed of Douglas fir bark mixed with wax and soybean oil mixed with apple powder (RR = 0.9).

Finally, one study from Córdoba in Spain evaluated the effect of diversionary feeding of rabbits on the vineyard yield, but found no reduced risk following diversionary feeding in comparison to the control (RR = 0.99).

Referenced papers
Barrio I.C., Bueno C.G., Tortosa F.S. (2010). Alternative food and rabbit damage in vineyards of southern Spain. Agriculture, Ecosystems & Environment, 138, p. 51-54.
Diversionary feeding practices did not have a significant effect on grapevine yield, but significantly reduced rabbit damage.
Sullivan, T. P., & Sullivan, D. S. (1988). Influence of Alternative Foods on Vole Populations and Damage in Apple Orchards. Wildlife Society Bulletin (1973-2006), 16(2), 170–175.
The study evaluated the effect of supplementary feeding on vole damage to apple trees, and observed reduced number of attacks in the presence of soybean oil logs but that the effect is dependent on the type of supplementary food.
Swihart, R.K. (1991), Modifying Scent-Marking Behavior to Reduce Woodchuck Damage to Fruit Trees. Ecological Applications, 1: 98-103.
The mean level of woodchuck damage to trees was not significantly reduced by the provision of scent-marking stations. Use of NaCl—treated stakes did not reduce damage to adjacent trees.