Development of feeding selectivity in roe deer.

The development of feeding behaviour in European roe deer (Capreolus capreolus) was studied using nine fawns, from birth to 1.5 months. They were offered individually, seven plant species in random order, one at a time, and their feeding behaviour recorded. The results were compared to the behaviour of eight adults offered the same plants, which were chosen to cover the whole range from preferred to strongly avoided plants. Fawns displayed selectivity towards the different plants from their first contact, and they appeared to respond initially to buccal, but not olfactory, stimuli. Thereafter consumption of the two preferred species increased, while use of the others remained at a very low level. For the two plant types most strongly avoided (and perhaps the most toxic), learning allowed the deer to distinguish and avoid the plants using olfactory (and perhaps also visual) stimuli. For the other three species, fawns continued to ingest small quantities which may have allowed them to learn to avoid these plants, using the association between taste and negative post-ingestive consequences. This process may also have been involved in the increases in the consumption of the two preferred species. The animals were able to discriminate to almost the same extent as adults by the time they were about 1 month old. These results underline the importance of learning, and identify some of the stimuli involved in the development and maintenance of the highly selective and flexible feeding behaviour of this herbivore.