Plasma levels of Androgen, Progesterone and gonadal development of breeders and helpers in the Jungle Babbler Turdoides striatus

Abstract

We examined the proximate causes of delayed breeding and helping (allo-parental) behaviour by measuring plasma testosterone and progesterone concentrations in female breeders, male breeders, and helpers in co-operatively breeding Jungle Babblers. No significant difference was noted in the body and gonadal weight of breeders and helpers females. Also testosterone levels in the blood plasma did not change significantly between breeding duo and helpers. This could be related to the fact that the reproductive activities (maintaining the territory, defending the nest etc.) are performed by all members of the flock. The progesterone levels and the size of oviduct were comparatively higher in breeding than in non-breeding females. In helper females, the level of this hormone was intermediate. This result suggests that helpers share all breeding activities (including parental, allo-parental behaviour) but subdued oviducal development prevents them from egg formation and egg laying.