Breeding system and social behaviour of the El Oro Prakeet (Pyrrhura orcesi)

Together with Nadine Klauke and Marie Lucas I am working on the breeding system and the underlying social organization of the endangered El Oro Parakeet (Pyrrhura orcesi) in Buenaventura Reserve, Ecuador. (Marie Lucas & Nadine Klauke)

In general, cooperative breeding can not be regarded as exceptional in the evolution of breeding behaviour. More than 200 bird species are known to raise their offspring with helpers at the nest.

In parrots, however, cooperation is indeed uncommon and is only described for very few species.

In my diploma thesis I will focus on the feeding behaviour and social interactions of flock members inside the nest. Therefore I installed videocameras in the top of 13 artificial nest boxes in Buenaventura Reserve. For individual identification we trapped the flock members of each nest and marked them with small cuts in the tail feathers and figures on the beak.

After revising the recorded video material I will firstly assess whether the El Oro Parakeet shows true cooperation or just communal breeding where the nest is used by different females to lay their eggs.

In the case of true cooperation the main questions will be: What is the underlying social organization within the flocks that enabled cooperation in this species and why do individuals forego own reproduction and help others to raise additional offspring instead?

One possible explanation provides the kin selection hypothesis of Hamilton that postulates that individuals can gain indirect fitness from helping to raise additional offspring of closely related conspecifics. Therefore I will determine differential investment of flock members in raising the chicks by measuring feeding time. Genetic kinship analysis (Marie Lucas) will allow to test for correlation between individual investment and the grade of relationship between feeder and chicks. Another possibility is a polyandrous mating system with dominance hierarchy between potential fathers. To test for this hypothesis I will assess social interactions considering (pseudo-) copulation, nest entering order, sentinel duties and aggressive behaviour. In addition to the data gained from video recordings I will as well use direct observations if flick members made in the field.