Did you learn what to eat from your parents? A test of the early learning of the foraging niche hypothesis in great tits Parus major

Abstract

A growing number of studies suggest that individuals can develop long-term foraging specializations independently of phenotypic or environmental variation, yet little is known about how the foraging niche is acquired. The early learning of the foraging niche hypothesis suggests a key role of vertical cultural transmission in shaping the foraging niche of vertebrates. In birds, direct evidence from natural conditions is limited to a single study that cross-fostered two related species. To date, no study has tested whether the diet received as an offspring determines the diet delivered as a parent within a single species. We tested the early learning of the foraging niche hypothesis using a Mediterranean population of great tits Parus major, which show great diet variability and moderate consistency in the diet they provide to their offspring across years. To do this, we recorded prey delivered to 9–14 day-old chicks over twelve years. Then we assessed vertical transmission of dietary specialization using data (percentage of caterpillars, spiders, and other prey types, as well as mean prey size) from individuals recorded as a chick and as an adult. We standardised the data to control for environmental factors and ran a Linear Model for each prey type to measure individuals' consistency within the group (relative consistency), correlating the diet they received as a chick and the one they provided to their own chicks at the adult stage. The correlations between the diet received as a chick and the diet provided as a parent were either not significant or negative. Hence, although individuals showed relatively consistent foraging niches across years regarding their parental provisioning behaviour, these diet preferences were not correlated to the diet they received in the nest. Further research is needed to determine whether the foraging niche is acquired during the post-fledgling stage.