Supplementary feeding of red deerSubmitted by editor on 17 December 2014.
Many years ago, on a cold winter night, we were sitting on a high-stand at the forest edge. We were waiting for the red deer to come to the feeding place. We wanted to trap some individuals and put radiocollars on them, and we expected that the huge amount of apple pomace provided as supplementary feed at the feeding place would attract some deer. But no deer arrived; only a red fox appeared and ate some apples. We had, therefore, enough time to wonder. What is the function of the intensive winter supplementary feeding of red deer? Is this only a tradition in our country, Hungary and other central European countries or is it a cost-effective adequate management measure?
We had a lot of questions. What kind of goal can be achieved through feeding of red deer by readily-available crops (e.g. corn, wheat, oat or rye) or cheap by-products (such as apple pomace)? Red deer is an intermediate feeder which primarily forages on browse. Can the supplementation of its natural diet by non-browse food be beneficial for red deer population and the game manager? The specific goal of a feeding program is not always clear. But based on the intensive feeding programs we presumed that supplementary food is the dominant component in the winter diet of red deer, and it is consumed by the majority of the individuals.
Some years later we initiated a research project in this area and another one about this issue. We aimed to determine the importance of supplementary feeding from the point of view of red deer. Therefore, we investigated: a) the proportion of the supplementary food compared to that of natural ones in the red deer diet and b) the proportion of the individuals using the feeding plots and consuming supplementary feed.
In our study we simultaneously utilised two complementary methods: microhistological analysis of faeces and rumen content, and macroscopic observation of natural (seed) and artificially mixed (rubber items) food markers.
Our results indicated that not every individual of the red deer population visits the feeders, or if does, eats a rather small amount of the provided food. Supplementary feed (maize silage and apple pomace) was never the dominant food component. It was a surprising result for us, since there are regular observations that the supplied food vanishes from the feeder in most cases. Nevertheless, it is not a contradiction.
Although we cannot go further in the evaluation of the effectiveness of supplementary feeding without additional experiments; it seems that the red deer population can have an obvious effect on supplementary feed, meanwhile that food may have little or no benefit to deer individuals.
But where does the enormous amount of supplementary feed go, if it is not the main diet component of red deer? Please read our paper How important is supplementary feed in the winter diet of red deer? A test in Hungary in Wildlife Biology, and you can find the answer!