How important is supplementary feed in the winter diet of red deer? A test in Hungary

Abstract

Winter supplementary feeding is widespread in large game management. As it is very expensive, it is important to know how essential this feeding may be for populations of game like red deer Cervus elaphus. Game managers typically observe only the disappearance of feed, but do not measure the consumption from the perspective of the animal, so the importance of feeding programs is often uncertain. During the winter of 2007-2008 we determined the consumption by red deer of two feed types (maize silage and apple pomace which is the residue from pressing apples) commonly offered at feeding plots in Hungary in two study areas. We simultaneously utilised two complementary methods: microhistological analysis of faeces and rumen content, and macroscopic observation of natural and artificially mixed food markers. Based on our analyses, 20 to 90% of the red deer (among different dates and measures) had eaten the supplementary food. However, the proportion of supplementary food in the red deer droppings collected in the immediate surroundings of the feeding plots was always very low (< 10%). This indicates that not every individual of the red deer population visits the feeders, or if does, eats a rather small amount of the provided food. Our data strongly suggests that supplementary food did not play a large role in the diet of the red deer individuals regularly visiting these sites. We emphasise that the mere observation that supplementary food regularly vanishes from the feeder does not necessarily mean that even one individual red deer has gained a significant biological advantage which would result in additional financial profit for the game manager later. Managers considering supplementary feeding should evaluate the quality of the forest area because the natural food supply can greatly influence the use of the feeding plots.