In South America, yellow fever (YF) is an established infectious disease that has been identified outside of its traditional endemic areas, affecting human and nonhuman primate (NHP) populations. In the epidemics that occurred in Argentina between 2007-2009, several outbreaks affecting humans and howler monkeys (Alouatta spp) were reported, highlighting the importance of this disease in the context of conservation medicine and public health policies. Considering the lack of information about YF dynamics in New World NHP, our main goal was to apply modelling tools to better understand YF transmission dynamics among endangered brown howler monkey (Alouatta guariba clamitans) populations in northeastern Argentina. Two complementary modelling tools were used to evaluate brown howler population dynamics in the presence of the disease: Vortex, a stochastic demographic simulation model, and Outbreak, a stochastic disease epidemiology simulation. The baseline model of YF disease epidemiology predicted a very high probability of population decline over the next 100 years. We believe the modelling approach discussed here is a reasonable description of the disease and its effects on the howler monkey population and can be useful to support evidence-based decision-making to guide actions at a regional level.

This study reports the first case of adoption in a wild group of black and gold howler monkeys (Alouatta caraya). After the death of one adult female with a dependent infant, her daughter with a dependent infant adopted the orphan of similar age of her own infant. We recorded the activity and proximity between the adopter and both infants during two following days. The adoptive female appeared to provide equal treatment toward both infants and the orphan seemed to recognize the female as his mother. This report suggests that adult females of A. caraya can rear two infants at once.

En este estudio se cita el primer caso de adopción en un grupo silvestre de monos aulladores negros y dorados (Alouatta caraya). Luego de la muerte de una hembra adulta, su hija adoptó al infante huérfano de similar edad que su propio infante. Durante dos días seguidos registramos la actividad y proximidad de la hembra adoptiva y los dos infantes. La hembra adoptiva expresó igual trato hacia ambos infantes y el infante huérfano parecía reconocer a la hembra como su propia madre. Este estudio sugiere que hembras adultas de A. caraya pueden criar dos infantes a la vez.