Evidence for long-term spatial memory in a parid.

Many animals use spatial memory. Although much work has examined the accuracy of spatial memory, few studies have explicitly focused on its longevity. The importance of long-term spatial memory for foraging has been demonstrated in several cases. However, the importance of such long-term memory for all animals is unclear. In this study, we present the first evidence that a parid species (the black-capped chickadee, Poecile atricapillus) can remember the location of a single food item for at least 6 months under an associative-learning spatial memory paradigm with multiple reinforcements. We did not detect a significant difference in memory longevity between two populations of chickadees shown previously to differ in short-term spatial memory and hippocampal morphology, an area of the brain involved in spatial memory. Our study showed that small birds such as parids can maintain spatial memories for long periods, a feat shown previously only in corvids. Moreover, we were able to demonstrate this longevity within the context of only 16 repeated trials. We speculate that this ability may potentially be useful in relocating caches if reinforced by repeated visits. Future studies are necessary to test whether our results were specifically due to multiple reinforcements of the food-containing location and whether parids may have similar memory longevity during food-caching experiences in the wild.