In theory, animals might respond to intense competition for food in either of two opposing ways. First, they could concentrate on becoming really good at finding certain foods, while ignoring others completely.
Alternatively, they could become less fussy and wolf down anything that might be vaguely edible.
But what do wild animals actually do? Among bands of banded mongoose, at least, it seems they specialise.
“Social animals can gain many benefits from group living, but they also suffer from competition over shared food resources,” says Michael Cant of the University of Exeter.
Each of a mongoose’s favourite foods – millipedes, ants, termites, beetles, frogs, mice and reptiles – leaves a distinctive chemical signature in the predators’ tissues. By plucking whiskers and analysing them, Cant’s team showed that as group-size (and hence, competition) increases, diets become narrower, with group members varying as to what they specialise in.
“The study helps to explain why animals vary so much in their foraging behaviour, even when they live in the same place and have access to the same food,” says Cant.