THE rutting of red deer evokes an iconic image of strength and power, in which mighty stags fight for dominance over groups of females in the breeding season.
New research, however, suggests that female deer also have an important role to play in determining which male gets the girl.
A long-term study of red deer on the Scottish Isle of Rum shows that females in heat will often move away from their usual ranges to mate with stags from other areas.
Stags tend to fight for control of groups – or harems – of females. However, scientists from the Universities of Edinburgh and Cambridge found that on average, 43% of female deer in heat will drift away from their usual range.
Of these, some two-thirds travel as more than two miles, and almost half will mate with stags from elsewhere.
Researchers say it is not clear why the females tend to wander. Their study shows females in heat do not favour large harems, older stags, or distantly related stags which pose less risk of inbreeding – all of which suggests that females are not moving in search of a preferred mate.
Scientists analysed 34 years’ worth of data from studies on Rum to determine how female deer behave during the rut.
Katie Stopher, of the University of Edinburgh’s School of Biological Sciences, who carried out the study, said: Females change harem during the autumn rut far more than we would expect. They are much more likely to do so when they are receptive to mating. It’s not clear why females stray, but it seems not to be out of preference for another stag. More work is needed to understand why this happens and what the implications are.”
The study, funded by the Natural Environment Research Council and the James Hutton Institute (formerly The Macaulay Institute) was published in Behavioral Ecology. Rum is a National Nature Reserve managed by Scottish Natural Heritage.