Instances of alloparental care in Great Tits (Parus major)

Abstract

Alloparenting refers to any type of parental care provided by an individual to non-descendant offspring. Alloparenting is not merely an altruistic behavior; it confers benefits to both care receivers and caregivers. Here, we report 3 cases where 3 adult Great Tits (Parus major) simultaneously provided food to chicks in the same nest boxes during the breeding season of 2019. All 3 cases were found in nest boxes where parent removal experiments were carried out. In our 3 d experiments, one of the parenting adults was temporarily removed from the nest box early on the second day and was back on its nest box at the end of that same day. In 2 of the nest boxes, the 3-adult brood-feeding started upon removing one of the brooding parents and continued on day 3, after the removed adult was returned. In one case, an alloparent was recorded feeding chicks alongside a parent since day 1 and continued feeding chicks on day 2. Our reports are the first documented examples of Great Tits involving a third adult in brooding. It presents an interesting finding for a well-studied bird species and may provide possibilities for in-depth research.