Individual-learning ability predicts social-foraging strategy in house sparrows

Abstract

Social foragers can use either a 'producer' strategy, which involves searching for food, or a 'scrounger' strategy, which involves joining others' food discoveries. While producers rely on personal information and past experience, we may ask whether the tendency to forage as a producer is related to being a better learner. To answer this question, we hand-raised house sparrow (Passer domesticus) nestlings that upon independence were given an individual-learning task that required them to associate colour signal and food presence. Following the testing phase, all fledglings were released into a shared aviary, and their social-foraging tendencies were measured. We found a significant positive correlation between individual's performance in the individual-learning task and subsequent tendency to use searching (producing) behaviour. Individual-learning score was negatively correlated with initial fear of the test apparatus and with body weight. However, the correlation between individual learning and searching remained significant after controlling for these variables. Since it was measured before the birds entered a social group, individual-learning ability could not be the outcome of being a producer. However, the two traits may be initially associated, or individual learning could facilitate producing behaviour. To our knowledge, this is the first evidence that associates individual-learning abilities with social-foraging strategies in animal groups.

Figure 1.

The proportion of fledglings that chose the correct well on each of the 20 trials in the individual-learning test (filled and open circles represent the first (n = 10) and second (n = 8) cohorts, respectively). (a) First testing day. (b) Second testing day.

Figure 2.

(a) The relationship between individual's score in the individual-learning test (a high score means better learning ability) and its searching rank (a high rank means higher searching proportion). (b) The relationship between individual's initial fear (log seconds) and its score in the individual-learning test. (c) The relationship between individual's initial fear and its searching rank.