Influence of incubation temperature on offspring phenotype and fitness in birds

Abstract Incubation is an important reproductive cost in birds. Because optimal development of avian embryos occurs within a narrow range of incubation temperatures, incubating birds are challenged to balance the demands of self-maintenance with the thermal requirements of developing embryos. the chapter's review shows that low incubation temperatures slow the development of avian embryos leading to longer incubation periods and reduced neonate quality. Embryos incubated at low temperatures generally use more energy which reduces the body mass and nutrient reserves of newly hatched chicks. Furthermore, this carries over to later life stages of young birds and negatively affects their subsequent growth, immunocompetence, metabolic rate, thermoregulatory ability, and locomotor performance. Evidence suggests that changes to the phenotypic quality of birds induced by low incubation temperatures reduce their survival, recruitment to the breeding population, and subsequent reproductive success. The chapter proposes additional research to test the strength, generality, and consequences of temperature-induced phenotypes in birds.