The youngest members of zebra finch broods "explore more" than older siblings in adult life, say scientists.

Researchers investigated how the birds' behaviour was affected by the way their parents cared for them as hatchlings.

The team studied broods where females lay and incubated a clutch of eggs over a period of days, resulting in a size hierarchy within the clutch.

They found the youngest birds were more likely to explore their environment as adults in search of food.