Habitat urbanization and stress response are primary predictors of personality variation in Northern cardinals (Cardinalis cardinalis)

Behavioral traits that vary consistently among individuals across different contexts are often termed as personality traits. The correlated suite formed by those traits, called a ‘behavioral syndrome’, can provide a more comprehensive way to view animal behavior. Both extrinsic and intrinsic ‘states’ (defined as strategically relevant individual features affecting the cost-and-benefit trade-offs of behavioral actions) have the potential to shape among-individual variation in personality traits, as well as behavioral syndromes. Here, we used Northern cardinals (Cardinalis cardinalis) sampled from four locations to examine the effect of habitat type (an extrinsic state), stress hormone corticosterone (CORT) parameters, body weight and sex (intrinsic states) on personality traits and behavioral syndrome variation. We used behavioral trials to measure five personality traits. Using principle component analysis (PCA) followed by general linear mixed model (GLMM), we found that habitat type, ...