Seasonal variation in CREB expression in the hippocampal formation of first-year migratory songbirds: Implications for the role of memory during migration

Abstract

Information is key to successful migration. Yet, how much information is learned and stored over the course of migration relative to other phases of the annual cycle is still unknown. We assessed seasonal variation in long-term memory formation indirectly by measuring the expression of cAMP response element binding protein (CREB) in hippocampal samples collected from migratory songbirds, Veery (Catharus fuscescens) and Wood Thrush (Hylocichla mustelina) at different life-history events (fall stopover, spring stopover, breeding season) during their first year of life. Consistent with our prediction, CREB expression was low during autumn (first) migration relative to levels in conspecifics during the first breeding season. These results suggest that young migratory birds may store relatively little spatial information during migration, particularly until they reach their wintering area and their global navigational map is more fully developed.