Predation on dependent offspring: a review of the consequences for mean expression and phenotypic plasticity in avian life history traits

Predation on dependent offspring (i.e., offspring that depend on parents for care) forms a critical source of natural selection that may shape a diversity of life history traits. Selection from predation risk on dependent offspring can influence life history strategies of both offspring and parents. Such selection may act on both the form of plastic responses (e.g., the shape of norms of reaction) and mean expression of traits. Consideration of both levels of responses is key to understanding the ecological and evolutionary role of predation on dependent offspring. Here, we discuss how plastic responses and mean expression of life history traits may respond to selection from predation on dependent offspring in nests of birds (i.e., nest predation). We then review the expected effects and evidence for a diversity of life history traits, including clutch size, egg size, renesting rates, onset of incubation, parental incubation behavior, development rates and period lengths, parental feeding behavior, nestling begging, and nest conspicuousness. The evidence demonstrates a broad role of nest predation on both phenotypic plasticity and mean expression of diverse traits, but evidence remains limited to a few studies on a limited variety of species for almost all traits, and much broader experimental tests are needed.