Summary: A new field study shows that female mountain chickadees in socially monogamous pairs often seek extra-pair matings with males that demonstrate superior spatial cognition. Researchers combined automated “smart” feeder arrays to measure individual spatial memory and detailed genetic parentage analysis across three breeding seasons. The results reveal that roughly 70% of nests contained at least one extra-pair chick and that the majority of those offspring were sired by males with exceptional spatial learning and memory.
High-performing males sired multiple extra-pair young each year—up to six or seven in some cases—and also produced heavier fledglings, which increases juvenile survival prospects. Interestingly, females who scored lower on the spatial cognition tests were the most likely to have extra-pair offspring, suggesting a strategic mating behavior that can improve the genetic prospects of their brood.
Key Facts
- Intellectual infidelity: Females in apparently monogamous mountain chickadee pairs frequently engage in extra-pair mating, preferentially with males that show stronger spatial learning and memory than their social mates.
- “Smart” feeder testing: Individual cognitive performance was quantified with automated feeders programmed so only a single location rewarded each tagged bird; fewer errors indicated better spatial cognition.
- High extra-pair rates: Over three breeding seasons, 70% of monitored nests contained extra-pair young, representing about one-third of the sampled chicks overall.
- Successful extra-pair sires: Top-performing males sired multiple extra-pair chicks per year without losing paternity or reducing chick quality in their own nests.
- Compensatory mating strategy: Females with poorer spatial cognition were significantly more likely to engage in extra-pair copulations, suggesting they seek genetic compensation for traits important to survival.
- Heavier fledglings: Males with superior spatial cognition tended to raise heavier chicks on average, improving offspring survival and entry into the breeding population.
Source: eLife
Females target males with better spatial skills
The study, published as a reviewed preprint in eLife, used rigorous genetic analyses and experimental field techniques to examine whether females prefer mates with better cognitive skills and whether such preferences affect reproductive success. The research focused on a wild population of North American mountain chickadees, a non-migratory, food-caching species that depends on precise spatial memory to recover thousands of hidden food items across variable terrain.
In many animal species, including birds that form pair bonds, females mate with multiple males. These extra-pair copulations can provide direct or indirect benefits, such as improved genetics for offspring. Because mountain chickadees rely on spatial cognition for survival and that trait is heritable, they provide a strong system for testing whether cognitive ability is under sexual selection.
Lead author Carrie Branch and colleagues used RFID-tagged birds and automated feeder arrays that only opened a reward at a single, individual-specific slot. By recording how many incorrect visits each bird made before finding its designated reward, researchers created an error-based measure of spatial learning and memory. They then cross-referenced those cognitive scores with parentage data obtained from genotyping across three breeding seasons.
The genetic results showed that roughly one in three offspring sampled were sired by males other than the social mate, and 70% of nests contained at least one extra-pair chick. Crucially, males with fewer feeder errors—indicating better spatial cognition—sired more extra-pair young than their lower-performing peers. These high-cognition males sometimes sired six to seven extra-pair offspring annually, a clear reproductive advantage that was independent of male age.
Examining reproductive fitness, the team found no evidence that males who pursued or fathered many extra-pair young lost paternity in their own nest. There was no reduction in the number or average mass of chicks in their social nests compared with other males. In fact, better spatial cognition correlated with heavier chicks overall, a trait associated with increased juvenile survival.
Interestingly, the probability of a male being cuckolded did not directly depend on his own spatial-cognition score. Instead, the strongest predictor of extra-pair young in a nest was the female’s cognitive performance: females that performed poorly on memory tests were more likely to produce extra-pair offspring. This pattern supports the idea that some females actively pursue extra-pair copulations to offset their own cognitive limitations and increase the likelihood their chicks inherit beneficial traits.
Senior author Vladimir Pravosudov explains that these results indicate female mate choice contributes to the evolution of spatial cognition in a species that depends on remembering thousands of food caches. Males with superior spatial abilities gain indirect fitness advantages through extra-pair matings and direct benefits through producing heavier, more viable offspring.
Key Questions Answered:
A: Mountain chickadees are non-migratory and face harsh, variable winters. They cache thousands of food items across broad areas and must remember the precise locations of many hidden seeds. Strong spatial memory directly affects survival—failures can lead to starvation—so spatial cognition has immediate fitness consequences in this ecology.
A: Scientists deployed automated “smart” feeder arrays and fitted birds with small RFID tags. Each bird had one feeder slot programmed to release a sunflower seed; visiting the wrong slots counted as errors. The number of mistakes before finding the reward provided a precise, repeatable metric of spatial learning and memory for each individual.
A: The study suggests that females with weaker spatial memory may actively seek extra-pair matings as an evolutionary strategy to improve their offspring’s genetic prospects. Rather than cuckoldry being solely driven by low-quality social males, the behavior appears linked to females attempting to compensate for their own deficiencies and secure “good genes” for their brood.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full for accuracy.
- Additional context and clarification were added by editorial staff.
About this animal neuroscience and mating research news
Author: Emily Packer
Source: eLife
Contact: Emily Packer – eLife
Image credit: Vladimir Pravosudov (CC BY 4.0)
Original Research: “Male chickadees with better spatial cognition sire more extra-pair young” by Branch CL et al., published in eLife. Open access.
Abstract
Male chickadees with better spatial cognition sire more extra-pair young
Across taxa, females often mate with multiple males even when social monogamy exists, and these extra-pair copulations can offer genetic benefits. Mountain chickadees are a useful model because they depend on spatial cognition to recover food caches, variation in spatial ability is heritable and linked to survival, and thus cognitive traits may be subject to sexual selection. By pairing precise spatial-cognition measurements from automated feeders with parentage data in a wild population, researchers show that males with superior spatial abilities sire more extra-pair young and produce heavier offspring. Extra-pair sires outperform the social males they cuckold, while females with poorer cognition are more likely to have extra-pair young—findings consistent with sexual selection shaping spatial cognition and with the good-genes hypothesis.