Female Chickadees Choose Smarter Mates

In the forests of North America, chickadees are known for their monogamous pair bonds. But new research shows that female chickadees don’t always stay faithful to their nestmates. Instead, they sometimes seek out extra partners, males with sharper minds.

The study, published as a Reviewed Preprint in eLife, reveals that females prefer males with stronger spatial cognition, the ability to remember and relocate food stores. These smarter males not only win more extra-pair copulations but also gain a reproductive advantage, siring more offspring than their less cognitively skilled rivals.

Across animal species, females often mate with more than one male, even in systems that appear monogamous. These extra-pair copulations can boost offspring fitness by providing genetic benefits.

“When it comes to selecting a mate, females tend to be the ‘choosier’ sex due to their inherent investment. Females seek ‘high-quality’ males to increase the likelihood of successful reproduction, good parental care, and the chance that their offspring inherit ‘good’ genes,” says Carrie Branch, Assistant Professor at Western University, Ontario, Canada.

She adds: “Cognitive abilities such as spatial learning and memory allow animals to succeed in variable environments and can be directly inherited and shaped by natural selection, but there is little evidence to show that females choose males with better cognitive abilities.”

The team studied wild mountain chickadees, small birds that rely heavily on memory to recover thousands of food caches. Using “smart” feeder arrays, they tested each bird’s ability to remember the correct location for sunflower seeds. The fewer mistakes a bird made, the stronger its spatial cognition.

Over three breeding seasons, the researchers tracked paternity. They found that males with better spatial learning sired more extra-pair young. Some of the top-performing males fathered six to seven extra-pair chicks a year. Age didn’t matter; cognitive skill was the decisive factor.

Interestingly, males who sired extra-pair offspring did not lose reproductive success in their own nests. The number of chicks and their mass were similar between extra-pair and social males. However, males with better cognition raised heavier chicks overall, which are more likely to survive and join the breeding population.

Importantly, the study confirmed that extra-pair males had better spatial abilities than the social males they cuckolded, even though they were not older. This suggests females deliberately choose smarter males over their partners.

The likelihood of being cuckolded wasn’t tied to the social male’s cognitive skills. Instead, females with weaker spatial abilities were more likely to have extra-pair young in their nests. This hints that females may seek out smarter mates to compensate for their own cognitive shortcomings.

“Our results show that female choice contributes to the evolution of spatial cognitive abilities in a species that stores and recovers thousands of food items and relies on spatial cognition for survival,” concludes Vladimir Pravosudov, Professor of Biology at the University of Nevada, Reno.

“Males with better spatial cognition sired more young and fledged heavier chicks, which are more likely to survive and enter the breeding population. Our findings add to the evidence supporting natural selection based on spatial cognitive abilities in wild chickadees.”

This study highlights how intelligence can shape mating strategies and survival in the wild. For chickadees, brains matter as much as beauty. Females are not just choosing partners for their songs or feathers; they are selecting for cognitive skills that may give their offspring a survival edge.