Environmental gradients often create different selective pressures among populations and may drive local adaptation. Along mountain slopes, heterogeneity occurs rapidly and predictably, resulting in local adaptions on a rather small spatial scale. Mountain chickadees are food-caching birds that inhabit a continuous elevation gradient associated with predictable variation in winter climate, such that birds living at higher elevations experience harsher winter conditions compared to their lower elevation counterparts. These birds use spatial cognition to recover their food stores and survive winter. Previous research shows that individuals at higher elevations exhibit superior cognitive abilities and associated brain morphology compared to their lower elevation counterparts. During my talk, I will present evidence for evolution by natural selection on the spatial cognitive abilities of mountain chickadees inhabiting these differentially harsh winter climates and the role females play in maintaining local adaptation.