Individual differences in risk‐taking affect foraging across different landscapes of fear

One of the strongest determinants of behavioural variation is the tradeoff
between resource gain and safety. Although classical theory predicts
optimal foraging under risk, empirical studies report large unexplained
variation in behaviour. Intrinsic individual differences in risk-taking
behaviour might contribute to this variation. By repeatedly exposing
individuals of a small mesopredator to different experimental landscapes
of risks and resources, we tested 1) whether individuals adjust their
foraging behaviour according to predictions of the general tradeoff
between energy gain and predation avoidance and 2) whether individuals
differ consistently and predictably from each other in how they solve this
tradeoff. Wild-caught individuals (n = 42) of the jumping spider Marpissa
muscosa, were subjected to repeated release and open-field tests to
quantify among-individual variation in boldness and activity.
Subsequently, individuals were tested in four foraging tests that differed
in risk level (white/dark background colour) and risk variation (constant
risk/variable risk simulated by bird dummy overflights) and contained
inaccessible but visually perceivable food patches. When exposed to a
white background, individuals reduced some aspects of movement and
foraging intensity, suggesting that the degree of camouflage serves as a
proxy of perceived risk in these predators. Short pulses of acute
predation risk, simulated by bird overflights, had only small effects on
aspects of foraging behaviour. Notably, a significant part of variation in
foraging was due to among-individual differences across risk landscapes
that are linked to consistent individual variation in activity, forming a
behavioural syndrome. Our results demonstrate the importance of
among-individual differences in behaviour of animals that forage under
different levels of perceived risk. Since these differences likely affect
food-web dynamics and have fitness consequences, future studies should
explore the mechanisms that maintain the observed variation in natural
populations.