Some species of birds that scatter-hoard food e.g. marsh tits, Parus palustris, use memory to retrieve stored food. These scatter-hoarding species have a larger hippocampus relative to the rest of the telencephalon than do species that store little or no food e.g. blue tits, P. caeruleus. The difference in relative hippocampal volume arises after the young have fledged from the nest and recent work on the dual ontogeny of the hippocampus and memory in hand-raised marsh tits suggests that some aspect of memory for retrieving food (whether or not stored by the bird) can stimulate hippocampal growth in juveniles at a relatively late stage in their development.