Seasonal reproduction in male pichis Zaedyus pichiy (Xenarthra: Dasypodidae) estimated by fecal androgen metabolites and testicular histology

Abstract

Poaching poses a threat to a wide variety of wildlife, and basic information about the biology of hunted species needs to be collected before their populations decline to the extent that requires drastic human intervention. As the survival of a species is related to its ability to reproduce, data on its reproductive cycle are necessary for the development of management strategies. The hypothesis was tested that the reproductive season of pichis (Zaedyus pichiy), small hibernating armadillos that inhabit arid environments in Argentina and Chile, is limited to spring months. Gonadal competence of semi-captive and wild-caught male pichis of Mendoza Province, Argentina was studied, by measuring fecal immunoreactive testosterone concentrations and evaluating spermatogenic activity. Results suggest that Z. pichiy is a seasonal breeder that regulates reproduction through photoperiodic cues. Gonadal competence was limited to a period of 3-5 months in spring and early summer and was reflected in enlarged testes, increased spermatogenesis, and significantly elevated fecal immunoreactive testosterone concentrations. The reproductive season for males from southern Mendoza was almost 6 weeks shorter than in the north. This fact, along with significant morphological differences between both groups, suggests that northern and southern pichis belong to two distinct populations. It is concluded that prolonged breeding seasons and more favorable environmental conditions in northern Mendoza favor a prolongation of the reproductive season that may allow pichis to breed later in the year, thus maximizing reproductive opportunities.