Social learning in birds and its role in shaping a foraging niche

Abstract

We briefly review the literature on social learning in birds, concluding that strong evidence exists mainly for predator recognition, song, mate choice and foraging. The mechanism of local enhancement may be more important than imitation for birds learning to forage, but the former mechanism may be sufficient for faithful transmission depending on the ecological circumstances. To date, most insights have been gained from birds in captivity. We present a study of social learning of foraging in two passerine birds in the wild, where we cross-fostered eggs between nests of blue tits, Cyanistes caeruleus and great tits, Parus major. Early learning causes a shift in the foraging sites used by the tits in the direction of the foster species. The shift in foraging niches was consistent across seasons, as showed by an analysis of prey items, and the effect lasted for life. The fact that young birds learn from their foster parents, and use this experience later when subsequently feeding their own offspring, suggests that foraging behaviour can be culturally transmitted over generations in the wild. It may therefore have both ecological and evolutionary consequences, some of which are discussed.

Figure 1.

Mean (+s.e.) volume of prey items provided by female and male blue tit and great tit parents. Open bars, controls; filled bars, cross-fostered (reared by the other species). Prey volume was estimated from length and width of prey relative to bill length of parent. Sample size (number of parents) is shown above the bars.

Figure 2.

Mean (+s.e.) volume of prey items provided by (a) blue tit and (b) great tit parents in relation to the age of parent. Open bars, controls; filled bars, cross-fostered (reared by the other species). Prey volume was estimated from length and width of prey relative to bill length of parent. Sample size (number of parents) is shown above the bars.

Figure 3.

Mean proportion (+s.e.) of various prey types provided by (a) blue tit and (b) great tit parents. Open bars, controls (70 blue tits, 79 great tits); filled bars, cross-fostered (reared by the other species; 67 blue tits, 65 great tits).

Figure 4.

Mean (+s.e.) proportion of (a) green larvae, and (b) spiders, provided by female and male blue tit and great tit parents. Open bars, controls; filled bars, cross-fostered (reared by the other species). Sample sizes as in figure 1.