Hippocampal Volume Does not Correlate With Food-Hoarding Rates in The Black-Capped Chickadee (Poecile Atricapillus) and Willow Tit (Parus Montanus)

Abstract

AbstractFood-hoarding birds use memory to relocate caches, and species that store thousands of scattered food items must have an extraordinary memory capacity to be able to relocate them. Because the hippocampus is important in the functioning of spatial memory, it is logical to assume that the amount of food stored should correlate with hippocampal volume. Previously, food-hoarding capacity has been used as the predictor variable for hippocampal volume. Using the opposite approach, I tested whether hippocampal volume can be used to predict the amount of food stored. The atricapilla complex, a superspecies in the Paridae, has a wide Holarctic distribution, with the Black-capped Chickadee (Poecile atricapillus) in America and the Willow Tit (Parus montanus) in Eurasia. Although they live in similar ecological conditions, the Willow Tit possesses a hippocampus almost twice the size of the Black-capped Chickadee's. I sampled hoarding intensities in Black-capped Chickadees in British Columbia with the same methods I used previously in Willow Tits in Sweden. Contrary to expectation, Black-capped Chickadees stored at the same high rates as Willow Tits, which suggests that both species are large-scale hoarders. I discuss possible explanations for why the difference in hippocampal volume did not translate into differences in food-hoarding rates.Le Volume de l'Hippocampe n'est pas Corrélé avec le Taux de Stockage de Nourriture Chez Poecile atricapillus et Parus montanus