Figure 8.5 Parental care versus parental survival. When researchers removed eggs from kestrel nests, fewer chicks were fledged but male and female parents experienced increased survival. Error bars are standard deviations. When eggs were added to the nest, more chicks were fledged, but it came at the cost of the parents experiencing decreased survival. Error bars are standard errors.
Data from C. Dijkstra, et al., Brood size manipulations in the kestrel (Falco tinnunculus): Effects on offspring and parental survival, Journal of Animal Ecology 59 (1990): 269–286.