Individual Variation in Cognitive Foraging Ability and Parenting in House Sparrows

Abstract

Foraging ability is a multifaceted concept involving an organism’s ability to collect food in an efficient manner using adaptive foraging strategies, spatial memory, and learning. The ability to find and collect ample amounts of food is critical to survival and successful reproduction, particularly in organisms that must supply food to their offspring. Individual variation in “cognitive foraging ability” could be a key factor in explaining consistent differences in the parenting ability among individuals. This novel idea was investigated by testing the ability of individual house sparrow (Passer domesticus) parents to solve a novel foraging task. To perform the test, foraging puzzles, which were composed of a platform containing nine small cups, were placed near 25 inhabited nest boxes. Over several days sparrows were trained to find mealworms in these cups. Foraging trials were performed by placing mealworms in the cups, then covering the cups with metal washers. Parents then had one hour to “solve” the puzzle by removing a washer to obtain the food. Measurements including times on board, amount of time on board and learning curve were analyzed to determine the cognitive foraging ability of the birds. This data was then compared to parental care data collected from the same birds, which included the rate and size of food items brought to nestlings. It was found that the ability to solve the puzzle did not predict any measure of nestling provisioning. This may have been due to the relatively small number of birds that solved the puzzle (nine birds). It was found that for those birds that performed the task, females took significantly longer to solve the puzzle than males. Individual variation in cognitive foraging ability did not explain variation in parental care; however, further refinement of this experiment to increase the number of parents performing the test could provide more conclusive results.