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Social Organization

Intragroup Social Interactions

Quantifying the social structure of social species, by determining who interacts with whom and how often, can help to identify the benefits gained by group living and provide insight into the evolution of sociality. I examine intragroup patterns of spatial associations and affiliative and agonistic interactions, and how these are influenced by age, sex, and genetic relatedness, as well as other factors.

Reproductive Strategies

Adult Female and Juvenile Playing

Adult Female and Juvenile Playing

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In order to investigate male and female reproductive strategies, I measured female estrogen and progesterone concentrations from fecal samples to determine the ovarian cycles and timing of ovulation. Onto these ovarian cycles, I mapped sociosexual behaviors, including copulations, as well as profiles of male fecal androgen and glucocorticoid concentrations, to examine the relative importance of male mate guarding and female mate choice. 

ITo further gain insight into male reproductive strategies, I collaborate with Dr. Anthony Di Fiore to conduct molecular analyses to determine paternity patterns. 

Since the onset of this research program in 2005, group members of six study groups have been systematically observed, which by now allows us to examine life history traits, such as age at first reproduction, interbirth intervals, lifetime reproductive success, among others. Such information is crucial in the development of conservation programs on the behalf of this endangered primate species. 

Dispersal Regimes

Dispersal patterns - who disperses when, where, and how - form the backbone of a species' social organization because they influence the potential of social interactions among related individuals both within and between groups. Dispersal patterns also influence the overall genetic population structure, and thus, the population viability.


Based on data from multi-year demographic patterns of six groups, combined with both cross-sectional and longitudinal data on genetic population structure, I examine male and female dispersal patterns in the black howler population at Palenque National Park, Mexico. 

With Dr. Keren Klass, we also study how dispersal patterns might be altered in the fragmented landscape surrounding Palenque National Park, where the potential to move to other groups is drastically changed by the conversion of tropical forest to agricultural or urban areas.

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