The role of personal reproductive experience on nest building in a wild bird

While much is known about the functions of avian nests in reproduction, the role of experience in nest building has often been overlooked, especially in natural populations. Increasing evidence from captive birds suggests that the environment an individual experiences affects nest-building decisions, as does reproductive experience. Here we asked whether in a wild population of blue tits Cyanistes caeruleus, experience affected: (i) the materials and/or amounts of material with which the birds chose to build, and/or (ii) the location in which they built. We investigated the material composition and effectiveness of nests built by female blue tits between 2016 and 2022. We found that (i) a high insulation: structure ratio was associated with higher hatching success; (ii) the rate at which nests cooled was faster the more offspring had fledged from that nest; (iii) individuals that successfully fledged at least 1 chick were more likely to reduce the amount of insulating material they put into their nest the following year than were blue tits that previously had been unsuccessful; (iv) for unsuccessful birds, changing the nest design the following year improved their fledgling success; and finally, (v) unsuccessful birds were also more likely to move to a different nestbox the following year. In sum, we find that wild blue tits used their experience of reproduction in 1 yr to change their building decisions the following year. This effect mirrors responses made by birds building in the laboratory but over a much longer time interval.