Volume 36, Issue 3, May/June 2025

Understanding the costs and benefits of group living, along with the impacts of group size on the behavior, has long interested evolutionary biologists. Leveraging a longitudinal dataset from a population of wild primates, we provide evidence that behavioral diversity and frequency of agonism are higher in larger groups. These factors may constrain group size and contribute to group fissions. Investigating how group size affects behavior contributes to understanding the dynamics and evolution of group living.

Migrating songbirds need to avoid becoming prey during stopover, but may not respond appropriately to free-roaming domestic cats, an introduced predator. We found that migrating songbirds changed their behavior when exposed to a model hawk but not to a live cat. Birds in our study could be naïve to domestic cats or may not respond until perceived risk is higher to save valuable energy during migration, which could increase their risk of predation by cats.

Rescue behavior in ants involves helping endangered nestmates. Our study examined several ant species, finding that those with longer worker lifespans were more likely to engage in rescue actions. This suggests life expectancy is a crucial factor influencing rescue behavior. These findings highlight the need for further research on the behavioral patterns of social insects.

When a dominant female meerkat was paired with an unfamiliar dominant male breeding partner, 10% of her offspring were not fathered by him. However, dominant females were not “trading up” to better or less related males or having better quality offspring as a result. Rather, extra-pair paternity increased when females were in good condition and had more extra-group mates available, and when dominant males were in poor condition and had few subordinate male helpers.

Losing the ability to recognize and respond with appropriate behaviors is thought to be an important factor in extinctions among island animals. We evaluated behavioral responses to taxidermy models on the California Channel Islands and found that breeding birds on Santa Rosa Island are not naive about Island Scrub-Jays, a nest predator only found on Santa Cruz Island. Our results have clear implications for managers considering translocating Island Scrub-Jays to Santa Rosa.

Animal personality differences (consistent among-individual behavioral differences) are ubiquitous, yet their evolution is little understood. We found sex-specific links between personality and reproductive success in a bi-parental cichlid. Bolder males were less likely to reproduce but raised a higher proportion of offspring through providing better care compared to less bold males. Those reproductive differences could help maintain variation in male boldness if they yield equal average fitness. Female boldness did not predict reproductive success.