In my Diploma thesis I investigate the social system of the endangered El Oro Parakeet (Pyrrhura orcesi). First studies have shown that this Parakeet is a facultative cooperative breeder. Moreover egg laying dates in large groups containing more than one female suggest that communal breeding groups also occur. By means of behavioural observations I will get insights into the social structure of the breeding groups. All individuals of a group will be captured and individually marked and behavioural observation will then be carried out with the help of nest cameras, which are installed in artificial nest boxes. Nest activity will be recorded for five days for each nest during the hatching phase. All field work will be carried out during breeding season (November-April) at the Buenaventura Reserve (owned by the Fundación Jocotoco) of Southwestern Ecuador.

To determine whether the degree of relatedness among flock members will affect the helping behaviour, I will investigate if more closely related individuals offer more help by provisioning for the offspring more frequently and if this behaviour represents an indirect benefit for the helpers. .

In addition, I will investigate in how far group size affects the breeding success in terms of parent and offspring survivorship. If the cooperative breeding system represents an evolutionary benefit for the El-Oro Parakeet, then larger groups should not only be able to provide for the offspring more easily, but probably also reduce stress levels for the breeding pair.

Consequently, parent and offspring mortality should be lower in larger breeding groups, compared to monogamous pairs. By carrying out genetic analyses of all flock members of a cooperatively breeding group, I will not only be able to determine if communal breeding e does occur, but also if this affects the helping behaviour of flock members (i.e. helpers showing different priorities when feeding chicks of different females).

To determine if cooperative breeding groups are governed by dominance hierarchies, I will record the order in which individuals are entering the nest and feeding the offspring. If so, cooperatively breeding flocks should be relatively stable, with reduced aggression among individuals: interactions occurring mostly between only two individuals often of similar social rank of the group.

My behavioural study is connected to the dissertation of Nadine Klauke and will be complemented by the genetic analyses of social groups.