Four hypotheses about the foraging-antipredation behavioural conflict using herbivorous rodents Cavia aperea were tested: (a) shorter residence times and (b) greater scanning rates, are expected in foraging areas progressively more distant from cover, because foraging at greater distances from cover would increment predation risk; as group foraging would facilitate predator detection, (c) shorter residence times and (d) greater scanning rates, are expected when cavies are alone than when they are in foraging groups. Over a total of 123 complete foraging bout observations, cavies always foraged at less than four m from the cover. The results support predictions (c) and (d), suggesting that (1) cavies improved their foraging efficiency by joining a group, which allowed them to produce longer bouts and to invest more time in grazing during bouts, and (2) foraging group formation had a role in antipredation defense. (b) was also supported, but in the case of (a), the observed relation was the opposite to the one expected, that is residence times were longer as distance to cover increased. Observed behaviour suggests that cavies reduce risk at greater distance to the cover by increasing their scanning rates and by progressively reaching more distant zones, foraging first in near ones, and returning to the cover in a hurry.
Cassini, MH: Foraging under Predation Risk in the Wild Guinea Pig Cavia aperea
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