Evaluación del nivel de estrés en leoncillos (<em>Cebuella pygmaea</em>) mediante la medición de cortisol en heces

The pygmy marmoset ( Cebuella pygmaea ) is the smallest platyrrhine primate. It lives in gallery forests in the Upper Amazon basin of Colombia, Ecuador, Peru, Bolivia and Brazil. Although all the Ecuadorian primate species are threatened by human activities, the pygmy marmoset is one of the most vulnerable due to its high specialization in diet and habitat. It is included in the list of vulnerable species in Ecuador. Anthropogenic alteration of the habitats is a stress factor for pygmy marmosets. In this context this study aimed to establish a protocol to measure cortisol concentration in feces (ng/g), as an indicator of the stress level of the individuals, and to make a preliminary comparison of the levels of cortisol and stress of three populations of pygmy marmosets in Amazonian Ecuador. Fifty two fecal samples from the wild populations of Tiputini and San Pablo, and one captive population from Puyo were analyzed. The samples analyzed had a dry weight between 0.05 and 0.07 g. The biological validation made with the fecal samples of an individual quarantined, showed that cortisol levels were higher in times closer to its death. The preliminary results suggest that the captive population from Puyo has higher levels of stress than the wild populations. These results have to be confirmed by analyzing a larger number of samples with information about the time of fecal deposition, the sex, age and previous activities of the individuals.