Meeting Abstract
Parental care (e.g. provisioning nestlings) is widely assumed to be costly, and life-history theory predicts that individuals that invest more in parental care should benefit in terms of number of offspring produced but that increased parental care might come at a cost in terms of decreased future fecundity and/or survival. However, the notion that parents that work “harder”, commonly measured by the rate at which parents visit the nest box to provision their chicks, produce more, fitter chicks is surprisingly poorly supported. One potential reason for this apparent lack of relationship between measured work load during parental care and breeding productivity is that nest visit rate does not provide a good measure of foraging effort (even though this is the most commonly used metric). During chick-rearing, provisioning birds can adjust their foraging behavior in many other ways, e.g. varying load size, prey type, foraging distance, etc. Here, we investigated effects of handicapping (i.e. wing clipping) on parental effort during reproduction on breeding European starlings, Sturnus vulgaris. Using an automated radio telemetry system we tracked individually breeding females for the entirety of the breeding period. Our data suggests that there is marked variation in foraging behaviour (activity level, load size, and prey type). Given that provisioning rate is highly variable, but not correlated with breeding productivity, we predict that load size will be negatively correlated with provisioning rate and that individuals who bring a greater proportion of Tipulidae larvae, the primary food source of starlings, will have greater reproductive success. From this multivariate data we examined the repeatability, during the first and consequent breeding attempts, of several foraging metrics (activity level, load size, and prey type) and whether that individual variation is correlated with breeding productivity.
