Meeting Abstract
Analysis of parental behavior during chick-rearing is often focused on activity at the nest, measured as provisioning rate Furthermore, data are often obtained only from “successful” birds. We used an automated radio tracking system to measure total activity in female European starlings (Sturnus vulgaris) 24/7 during late incubation and chick-rearing in both successful and failed birds. Tracking data revealed novel, aspects of parental behavior, e.g. a) large inter-individual variation in activity during incubation, b) putative nocturnal foraging bouts, but c) high repeatability of individual variation in activity across breeding stages. In successful birds, total activity was not correlated with provisioning rate and we suggest that this is because only a component of total activity is directed towards, or required for, successful rearing of chicks. Additional activity of parents appears to constitute “self-maintenance” behaviour, i.e. “activity” which might explain different ‘strategies’ for maximizing fitness. Nest failure rates were higher in second broods than in first broods, but more birds failed early (before hatching) in first broods, i.e. parents persisted with parental care for longer in second broods before nest failure. For first broods, there was no difference in diurnal or nocturnal activity level of failed vs. successful birds during incubation, but birds that failed had lower total activity levels during chick-rearing even prior to breeding failure. Our activity data suggest that natural populations harbor “couch potatoes” and “athletes”. We discuss whether nocturnal activity, or off-nest activity during incubation, represent foraging for self-maintenance or opportunities for exercise allowing birds ‘to get in shape’ ready for chick-rearing.
