A simple cage test captures intrinsic differences in aspects of personality across individuals in a passerine bird

► We assay four personality traits in wild blue tits using a simple cage-based protocol.
► Two personality traits are found to be significantly repeatable.
► One personality trait (escape) is associated with a polymorphism in the DRD4 gene.
► Our protocol allows rapid testing of personality traits in a standard environment.
► Our approach captures consistent, heritable personality aspects in wild individuals.