Consistent individual differences in paternal behavior: A field study of three-spined stickleback

Consistent individual differences in parenting are widespread; however, we know little about why there is variation in parenting behavior among individuals within species. One possible explanation for consistent individual differences in parenting is that individuals invest in different aspects of parental care, such as provisioning or defense. In this field study, we measured consistent individual differences in parenting behavior and evaluated correlations between parenting and other behaviors in three-spined stickleback (Gasterosteus aculeatus). We repeatedly measured male parenting behavior and male behavior in the presence of three different types of live intruders: a female, a conspecific male, and a predator, meant to provoke courtship, aggressive, and antipredator behavior, respectively. While males plastically adjusted their reactions to different types of intruders, we found consistent individual differences in behavior (behavioral types) both within and across contexts, even after accounting for variation in body size and nest characteristics. Males that performedmore parenting behavior responded faster to all types of intruders. These results suggest that in nature, individual male sticklebacks exhibit robust parental behavioral types, and highly parental males are more attentive to their surroundings. Future studies are needed to examine the potential causes of individual variation in parental behavior in the field.