Family group structure of the endangered Yellow Cardinal (Gubernatrix cristata)

The monogamous mating system, where a male and a female constitute the reproductive unit and share the parental care, predominates among bird reproductive strategies. However, there are also other mating systems with diverse parental care roles which may have implications for population breeding success and be relevant for their management and conservation. We evaluated the family group structure of the Yellow Cardinal ( Gubernatrix cristata) in La Pampa province of central Argentina. During the 2020–2021 breeding season we carried out 280 bird surveys to search for the presence of Yellow Cardinals. We registered 87 individuals (11 solitary individuals, 12 pairs, two males together, and 13 family groups). Most family groups corresponded to the typical monogamous structure, but two family groups (8%) were composed of two adult males, an adult female and at least a juvenile. We also explored 1646 Yellow Cardinal records at citizen science platforms and none of them included a family group with more than two adults. Even so, it would be feasible to release seized groups of two males together, to promote breeding success. Further studies are necessary to evaluate the causes of the presence of extra males and their incidence on the breeding performance of this globally endangered species. This may help to understand its natural history and for planning management and conservation actions.