Who are the innovators? A field experiment with 2 passerine species

Ecological and evolutionary drivers of innovativeness among species are relatively well studied, but the significance of similar variation within species is much less well understood. Using automated foraging devices, we conducted the first large-scale study of novel problem-solving performance in a wild bird population to test whether variation in innovativeness can be explained by inherent individual differences and by factors related to the "necessity drives innovation" hypothesis. We detected 20145 visits by 236 great tits (Parus major) and blue tits (Cyanistes caeruleus) and found consistent individual differences in the propensity to solve and in the time spent at devices between successive solutions in the field. Although individuals that were successful in a similar version of the task in captivity solved 3 times faster in the wild than those that were unsuccessful in captivity, success in captivity did not predict success in the wild. Thus, innovative propensity varies among individuals but it is also context dependent. Juveniles were more likely to solve the problem in the wild than adults, supporting the necessity drives innovation hypothesis. We found no evidence for social learning at problem-solving devices in the wild. The consistent individual differences in novel problem-solving performance we report suggest that innovativeness may be of adaptive significance within our population. Our results also suggest that selection for innovativeness may occur primarily among juveniles. Copyright 2011, Oxford University Press.