Study site and study population
The study was conducted at the Estación Biológica Quebrada Blanco in the
north-eastern Peruvian Amazon (4°21’S, 73°09’W) in June 2017 –
September 2019. Study individuals belonged to 14 family groups
(Supplementary Supplementary Table 1, Fig. 1), seven of which (Groups
1–7) were also subject to behavioral studies (Dolotovskaya & Heymann,
2020; Dolotovskaya, Walker, & Heymann, 2019). Group 1 had been
habituated to the presence of human observers and studied intermittently
since 1997; the other groups were habituated during this study. We
individually identified all the study animals based on the combination
of body size, tail shape and colouration, genitalia shape and natural
marks. Adult females and males were identified based on genitalia shape
and body size and shape.