|Elevation-related and age-structural differences in survival of wild, food-caching mountain chickadees|
|Lauren M. Benedict1, Carrie L. Branch2, Angela M. Pitera1, Dovid Y. Kozlovsky3, Benjamin R. Sonnenberg1, Vladimir V. Pravosudov1. 1University of Nevada, Reno, Reno, NV, United States; 2Cornell Lab of Ornithology, Ithaca, NY, United States; 3University of Ottawa, Ottawa, ON, Canada
For many residents of temperate climates, winter presents the most energetically demanding conditions and contributes to the largest annual post-dispersal mortality event. Food-caching is a common strategy to cope with seasonality and the ability to recover previously stored food is critical to overwinter survival. As such, we expect that cognitive abilities necessary to retrieve caches would be under selection in harsh environments. Adverse winter conditions intensify at higher elevations, leading to variation in environmental harshness across an elevational gradient. Previous work in our long-term study system of mountain chickadees (Poecile gambeli) shows that birds at our higher elevation site experience harsher conditions, cache more food items, have better spatial cognition and experience stronger selection pressures than birds at our lower elevation site. Here, we will present a survival analysis using capture-recapture data in wild, food-caching mountain chickadees testing whether harsher conditions at higher elevations impose stronger selection pressure by comparing overwinter survival between ages (first year vs. adult) and between high and low elevations.