Developmental Stress and Correlated Cognitive Traits in Songbirds

Early-life environments have profound influence on shaping the adult phenotype. Specifically, stressful rearing environments can have long-term consequences on adult physiology, neural functioning, and cognitive ability. While there is extensive biomedical literature regarding developmental stress, recent research in songbirds highlights similar findings in domesticated and non-domesticated species, opening up the field to broader questions with an ecological and evolutionary focus. Here, we review the literature in songbirds that exemplifies how developmental stress can shape birdsong, a sexually selected cognitive trait, and other physiological and cognitive abilities. Furthermore, we review how various traits can be correlated in adulthood as a result of various systems developing in tandem under stressful conditions. In particular, birdsong may be indicative of other cognitive abilities, which we explore in depth with current research regarding spatial cognition. In addition, we discuss how various personality traits can also be influenced by the intensity and timing of developmental stress (prenatal versus postnatal). We conclude by highlighting important considerations for future research, such as how assessing cognitive abilities is often constrained by experimental focus and more weight should be given to outcomes of reproductive success and fitness.