When herd animals, such as deer, flee from predators, they appear to coordinate with one another to avoid collisions and maintain group cohesion. How is this synchronized flight from danger achieved?
Recently, a group of scientists led by zoologist Hynek Burda of the University of Duisburg-Essen in Germany and doctoral student Petr Obleser of the Czech University of Life Sciences tested the possibility that roe deer (Capreolus capreolus) use magnetoreception—a sensitivity to the Earth’s magnetic field— to coordinate their escape when threatened. Building on previous findings that roe deer are most likely to align their bodies along the north-south axis while grazing and resting, the team investigated whether or not the animals also tend to escape in a north or south direction.
The researchers evaluated deer behavior at sixty locations across three hunting grounds within the Czech Republic. Experienced wildlife biologists and rangers approached the animals at each site, carefully noting a number of factors including the weather, sun position, wind direction, visibility, proximity to shelter, and their own distance from the deer, until they startled the animals. Direction of escape was then recorded.
The deer tended to flee along the axis with which they were already aligned. Overall, they were more likely to escape toward the north or south, rather than east or west, with little influence from environmental variables. Further, says Burda, “The tendency to choose north or south as a direction for escape was even more pronounced in animals in a group than in singles.”
The researchers plan to extend their study of this phenomenon to other locations and seasons, thereby including more and larger groups of animals. “We might study animals under or in the vicinity of high voltage power lines where the magnetic field— and thus magnetoreception—is disturbed,” says Burda. These inquiries would further our understanding not only of escape readiness in ungulates, but also of the impact of geomagnetism on animals’ mental mapping of space. (Behavioral Ecology & Sociobiology)