Trees know when deer are eating them — and how to fight back


In spring, the young, delicate shoots in the forest light up, bright and May green. The buds and shoots are the future of the forests as they allow young trees to grow. The problem for the trees is: Roe deer like to eat them, and especially their buds.
In order to protect themselves against roe deer browsing, trees purposely put up a fight,  are able to recognize precisely whether a branch or bud has been purposefully nibbled off by a roe deer—or just randomly torn off by a storm or other mechanical disturbance. The saliva of the animals gives them the signal. If a deer feeds on a tree and leaves its saliva behind, the tree will increase its production of . This hormone, in turn, signals to the plant to increase the production of specific tannins. It is known for some of these substances that they influence the feeding behaviour of roe deer, with the result that the deer lose their appetite for the shoots and buds.

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