Meeting Abstract
A habitat’s resource distribution should dictate how much time and energy an animal must spend foraging and may influence the level of spatial memory required to successfully remember foraging locations. As a result, hippocampal morphology (the region of the brain associated with spatial memory) may change depending upon habitat. Previous work suggests that birds utilizing less space and a reduced need for spatial memory show less hippocampal morphological advancement (region volume and dendrite structure), but this effect is reversible. To examine this phenomenon within an ecologically-relevant setting, we tested the hypothesis that wild dark-eyed juncos (Junco hyemalis) exhibit differences in the neural mechanisms that support spatial memory as a function of foraging area (rural vs. urban environments). Using radiotelemetry, we documented differences in space use by juncos in the different environments; home range sizes of rural birds were larger than those from the urban habitat. The rural birds traveled larger distances during the day, while urban birds remained close to residential feeders, even when roosting. We then sacrificed these birds and used Nissl stain along with stereological technique to analyze hippocampal volume and total neuron numbers. We found that the hippocampal volume of rural birds was significantly larger than urban birds; however, there was no difference in neuron number between groups. These results suggest that the distributions of resources within a habitat affect hippocampal volume but not neuron numbers. These differences in volume may be a function of connectivity within the hippocampus, demonstrating that animals’ use of space in a natural setting can influence their hippocampal morphology and plasticity.
