Foraging sparrows exhibit individual differences but not a syndrome when responding to multiple kinds of novelty

Abstract

Differences between individuals in correlated responses across contexts have both functional and mechanistic implications. Such syndromes may have either beneficial or harmful consequences when novel changes in the environment occur. We used wild-caught house sparrows, Passer domesticus, to test in functionally relevant circumstances, whether neophobia (initial fear of novelty), habituation, and the learning of novel cues (discriminant learning) were linked by a common underlying mechanism or reflected separate processes. We repeatedly measured individual latencies to approach and also to feed from a familiar feeding site in 3 contexts: a baseline control for mild disturbance, in the presence of a novel object and to a novel cue indicating hidden food. House sparrows on average exhibited neophobia, habituated to novel objects, and learned to associate new cues with a reward. We also found evidence for consistent individual differences in both latencies within most contexts but there was no evidence of individual differences in plasticity with repeated trials within either the novel object (habituation) or novel cue (learning) contexts. There was also little or no correlation between the 2 latencies within individuals within contexts. Individual differences in latencies to arrive at the food station exhibited strong correlations across contexts but latencies to feed were weaker. These results suggest a personality trait that exists regardless of novelty but no syndrome affecting reactions to different forms of novelty. House sparrows appear strongly plastic when responding to novel environments. Such plasticity is likely favored by the varied consequences of novelty across environments.