Extra-pair paternity in the socially polygynous Strange-tailed Tyrant, Alectrurus risora (Aves: Tyrannidae).

MAHLER, BETTINA; DI GIACOMO, ADRIÁN S.; DI GIACOMO, ALEJANDRO G.; REBOREDA, JUAN C.

Lund

Congreso; 14th International Behavioral Ecology Congress; 2012

ISBE

The Strange-tailed Tyrant (Alectrurus risora, Tyrannidae) is a fluvicoline flycatcher that inhabits savannas, wet grasslands and marshes in southern Paraguay and northeast Argentina. This species is highly sexually dimorphic, with males having a highly conspicuous tail with modified outer feathers that is displayed during nuptial flights. On the basis of observations of a breeding population over five consecutive breeding seasons we determined that the social mating system of this species was polygyny. Males defended contiguous territories of 2 ha that included the territories of 2-4 females. Females provided the totality of parental care and bred in the same area over several years, but males rarely bred in the same area in consecutive years. In this work, we examined paternity of territorial males on the chicks within their territories using 8 microsatellite loci. Genetic analyses revealed that for some male territories chicks were not fathered by the territorial male, indicating that females copulate with males not guarding their territories. The success of males in defending their territories might be related to their quality or to the presence of high perching sites within their territories.