Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Psychology

Program Name/Specialization

Behavioural Neuroscience

Faculty/School

Faculty of Science

First Advisor

David J. White

Advisor Role

Supervisor

Abstract

Cognition is widely believed to be adaptive, yet few studies directly show that variation in cognitive performance is related to fitness. Brown-headed cowbirds (Molothrus ater) provide a powerful system for addressing this gap because brood parasitism creates strikingly different reproductive problems for females and males. Females face the spatial demands of nest-prospecting, whereas males face social and competitive demands associated with access to mates. Across five experiments, cowbirds were tested on an outdoor foraging task designed as an analogue of nest prospecting, with manipulations of retention interval, cue conflict, and breeding condition, followed by observations of reproductive behaviour. Females did not show a general spatial advantage over males, and increasing retention interval did not reveal the predicted female superiority. Instead, the strongest sex difference emerged in cue use: when stimulus-bound and place-based cues were dissociated, females relied more strongly on the place-based cue (previously rewarded spatial location), whereas males showed relatively greater attraction to the displaced stimulus-bound cue (bundle of sticks or stones). Females' spatial performance also significantly improved during the breeding season, suggesting seasonal modulation of spatial performance when nest-prospecting demands are most relevant. Most notably, male local-cue use was positively associated with pair-bond copulatory success, linking cognitive strategy to a fitness-related reproductive outcome.  These findings suggest that sex differences in cognition are best understood not as broad differences in ability, but as differences in ecological relevance and strategy use.

Convocation Year

2026

Convocation Season

Fall

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Available for download on Sunday, September 27, 2026

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