Reproductive success and individual variation in feeding frequency of House Sparrows (Passer domesticus)

Parental care is assumed to be closely associated with individual differences in reproductive success. We investigated how feeding frequencies varied among parents and how this affected the subsequent reproductive success in insular populations of House Sparrows Passer domesticus in northern Norway. Female parents fed their offspring more than male parents did, and the feeding rates were positively related to the feeding rates of the partner. A positive relationship between feeding rates and bill depth was present in females. In males, the feeding rates were negatively related to total badge size and positively related to visible badge size, after the effect of other variables had been taken into account. A non-linear convex relationship between feeding frequency and hatch day was present in males, which could reflect either the seasonal change in weather conditions or the seasonal variation in food availability. For both sexes, feeding frequencies increased with increasing brood size, but at the same time the average feeding rate per nestling decreased with increased brood sizes. Finally, our results indicate that the amount of parental investment, measured as feeding rates during the nestling stage, may have a positive long-term influence both on the number of fledglings that recruit as well as the probability that fledglings survive until recruitment.