Flexible Helping Behaviour in the Azure‐Winged Magpie

Abstract

Helping to rear the offspring of others may be a way for younger birds to gain access to future reproduction especially when turnover of breeding opportunities is low. However, this explanation is not applicable to cases where adults also help, or when roles shift between helpers and breeders. Over a period of 6‐yr, we studied a marked population of azure‐winged Magpie (Cyanopica cyanus) breeding in a non‐territorial, colonial system. Magpies bred in a highly flexible cooperative system, in which individuals helped at different stages of the breeding cycle, including nest building, feeding the incubating female and feeding the young and removing the faecal sacs. On average, 50% of hatched nests were assisted by helpers‐at‐the‐nest, and nest success appeared to be positively related to the presence of helpers. Helpers were predominantly males. Although juveniles were more likely to help, both juvenile and adult birds helped. Individual birds behaved as helpers either as a first‐option or after having attempted their own breeding (second‐option helpers). An individual helper may assist more than one nest during the same breeding season and in different breeding seasons. Reversals between breeder and helper roles were common in both directions, within a breeding season and between years. Helping behaviour is an option for almost any member of the colony. Therefore, hypotheses related to the enhancement of future breeding opportunities for juveniles can be discarded as general explanation of helping in this species. Although the decision to help appeared to be influenced by proximal environmental conditions hindering successful breeding, the associated benefits of helping as opposed to simply recovering for future reproduction, especially for former breeders, deserve further study.

Nest sanitation in passerine birds: implications for egg rejection in hosts of brood parasites

“…Parents and helpers removed fecal sacs and debris, such as dry leaves and twigs (Alvarez 1975). Azure-winged Magpies breed in a highly flexible cooperative system, which includes helpers that remove fecal sacs from nests (Valencia et al 2003). Other species in the family Corvidae whose helpers performed nest sanitation were Florida Scrub-Jay and American Crow (Supplementary Material 2).…”

Female and male plumage brightness correlate with nesting failure in azure-winged magpies Cyanopica cyanus

“…A total of 143 birds were captured and marked. Sex of breeders was always assigned according to their behaviour, being scored as females those individuals that incubated the eggs and brooded the young (Valencia et al 2003). Age was assigned using moult extension, following Cruz et al (1992) as: juveniles, birds born in the previous year, and adults, birds older that one year.…”

“…Early monitoring of every nest allowed us to identify the members of the breeding pair before the chick hatched. About 50% of nests in our population present a helper (Valencia et al 2003). Helpers usually join the breeding group after the chicks hatched and only occasionally feed the incubating female (Valencia et al 2006), thus it is always possible to differentiate them from the male breeder.…”

Azure‐winged Magpies Cyanopica cyanus trade off reproductive success and parental care by establishing a size hierarchy among nestlings

“…), is significantly lower than that in western populations, 38–50% (Valencia et al . , Carranza et al . ).…”