Comparative Behavioral Syndromes in Mammals

Abstract

Behavioral syndromes -- consistent, correlated suites of behaviors that differ among individuals within a population and are maintained across contexts -- have emerged as a central concept in behavioral ecology, with implications for evolutionary theory, population dynamics, and conservation biology. This study conducted the first systematic cross-species comparative analysis of behavioral syndrome structure in mammals, quantifying boldness, exploration, sociability, aggression, and activity behaviors in 847 individuals across 36 mammalian species spanning seven orders. Behavioral consistency (repeatability) was estimated via linear mixed models across 2-5 repeated assays per individual, and among-trait correlations were quantified using multivariate random effects models to characterise syndrome structure. Mean behavioral repeatability averaged 0.54 +- 0.14 across species and traits, confirming the ubiquity of animal personality in mammals. Behavioral syndrome tightness -- the strength of among-trait correlations constituting the syndrome -- varied significantly among species (mean r = 0.42 +- 0.18) and was positively associated with both social group size (PGLS: R2 = 0.64, p < 0.001) and habitat heterogeneity (R2 = 0.58, p < 0.001), and negatively associated with home range size (R2 = 0.47, p < 0.001). Bold individuals showed significantly higher daily movement rates (+28.4%), broader diet breadth (+18.7%), and higher overwinter survival in stable environments (+12.4%) but lower survival under novel predation pressure (-22.8%) than shy conspecifics. These fitness landscape differences confirm that behavioral polymorphism is maintained by fluctuating selection across environmental contexts. Conservation implications include the recognition that behavioral syndrome composition influences reintroduction success, invasiveness potential, and population resilience to stochastic perturbation.