About

Karen B. Strier is the Vilas Research Professor and Irven DeVore Professor of Anthropology at the University of Wisconsin–Madison. Her main research interests focus on understanding the behavioral ecology of primates from a comparative perspective and contributing to conservation efforts for these species. Since 1982, she has studied the northern muriqui (Brachyteles hypoxanthus) in Brazil’s Atlantic forest, which serves as a model for comparisons with other primates and is one of the most critically endangered primates in the world. Her long-term field study aims to understand how stochastic demographic fluctuations and individual life histories influence population viability and behavior. Additionally, she is interested in understanding population-level variation and its relevance to basic research in biological anthropology.

Research topics

• Biology
• Ecology
• Mathematics
• Zoology
• Genetics
• Demography
• Evolutionary biology

Selected publications

• Book Review: Echoes of our Origins: Baboons, Humans, and Nature. By Shirely C. Strum (with Cassandra Phillips). Johns Hopkins University Press, 2025.

  International Journal of Primatology · 2026-01-30

  article1st authorCorresponding
  PublisherDOI

• Age–Sex Class Variation in the Activity Budget and Diet of Rhinopithecus bieti in Association with Monthly Temperature

  International Journal of Primatology · 2026-03-10

  articleOpen access

  Abstract The energy and nutrient costs associated with body mass, age, and sex can influence variation in primate behavior and diet. However, comparatively little is known about how these factors affect the behavioral and dietary flexibility of Asian colobines in response to intra-annual climate shifts. We collected data on an isolated population of black-and-white snub-nosed monkeys ( Rhinopithecus bieti ) at Mt. Lasha in the Yunling Provincial Nature Reserve, Yunnan, China, using instantaneous and scan sampling across 32 months between May 2008 and August 2016 to assess the association of temperature on the activity budgets and diets among and within age-sex classes. Adult females spent more time feeding, juveniles spent more time moving and less time resting, and adult males spent less time moving and more time resting than other age-sex classes. We did not detect any significant variation in diet across age-sex classes. This population spent more time feeding and less time moving and resting in colder months than in warmer months; however, we only detected these temperature-related effects within age-sex classes for moving and resting, not feeding. This population also spent more time feeding on lichen during colder months than during warmer months, a finding that cannot be explained by temperature-related dietary shifts within age-sex classes because their diets remained stable throughout the year. Our results suggest that intra-annual variation in temperature may amplify the distinct physiological demands among different age-sex classes, leading to greater shifts in activity patterns than in diet composition.

  PublisherOA PDFDOI

• A Primatologist’s Guide to Global Environmental Policies

  International Journal of Primatology · 2026-01-30

  articleOpen access1st authorCorresponding
  PublisherOA PDFDOI

• Reproductive inequality in humans and other mammals

  London School of Economics and Political Science Research Online (London School of Economics and Political Science) · 2025-03-19

  articleOpen access

  To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women's fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species-including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.

  PublisherOA PDFDOI

• Truth at the Crossroads

  Annual Review of Anthropology · 2025-10-21

  articleSenior author
  PublisherDOI

• Assessing group size and the demographic composition of a canopy‐dwelling primate, the northern muriqui ( <i>Brachyteles hypoxanthus</i> ), using arboreal camera trapping and genetic tagging

  Remote Sensing in Ecology and Conservation · 2025-10-17 · 1 citations

  articleOpen access

  Abstract Obtaining accurate population measures of endangered species is critical for effective conservation and management actions and to evaluate their success over time. However, determining the population size and demographic composition of most canopy forest‐dwelling species has proven to be challenging. Here, we apply two non‐invasive biomonitoring methods, arboreal camera trap and genetic tagging of fecal samples, to estimate the population size of a critically endangered primate, the northern muriqui ( Brachyteles hypoxanthus ), in the Caparaó National Park, Brazil. When comparing group sizes between camera trapping and genetic tagging, the genetic tagging survey estimated fewer individuals for one of the muriqui groups studied but showed slightly higher population size estimates for the other group. In terms of the cost‐efficiency of both methods, arboreal camera trapping had high initial costs but was more cost‐effective in the long term. Genetic tagging, on the other hand, did not require expensive equipment for data collection but had higher associated expenses for laboratory consumables and data processing. We recommend the use of both methods for northern muriqui monitoring and provide suggestions for improving the implementation of these non‐invasive methods for future routine monitoring. Our findings also highlight the potential of arboreal camera trapping and genetic tagging for other arboreal mammals in tropical forests.

  PublisherDOI

• The last remaining southern muriquis <i>Brachyteles arachnoides</i> from the interior of São Paulo state, Brazil

  Oryx · 2025-01-01

  articleOpen accessSenior author
  PublisherOA PDFDOI

• Ficha de Brachyteles hypoxanthus

  Datasets - Sistema SALVE - ICMBio · 2025-02-04

  datasetOpen access
  PublisherDOI

• Dynamic unpredictability in grouping

  Behavioral and Brain Sciences · 2025-01-01

  articleSenior author

  Dunbar presents an intriguing analysis of variance in primate group sizes, and social glue's (grooming) relationship to cognitive evolution. This focus on primates with consistent and stable grouping excludes perspectives on the evolution of grouping beyond predation and competition. The analysis raises important questions about variation, dynamic sizes, and the conservation implications of variance for primate population extinction vulnerabilities.

  PublisherDOI

• Assessing group size and the demographic composition of unhabituated northern muriqui ( <i>Brachyteles hypoxanthus</i> ) using non-invasive biomonitoring

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-12-17

  preprintOpen access

  Abstract Obtaining accurate population measures of endangered species is critical for effective conservation and management actions and to evaluate their success overtime. However, determining the population size and demographic composition of most canopy forest-dwelling species has proven to be challenging. Here, we apply two non-invasive biomonitoring methods, arboreal camera trap and genetic tagging of faecal samples, to estimate the population size of a critically endangered primate, the northern muriqui ( Brachyteles hypoxanthus ), in the Caparaó National Park, Brazil. When comparing population sizes between camera trapping and genetic tagging, the genetic tagging survey estimated fewer individuals for one of the muriqui groups studied but showed slightly higher population size estimates for the other group. In terms of the cost-efficiency of both methods, arboreal camera trapping had high initial costs but was more cost-effective in the long-term. Genetic tagging on the other hand did not require expensive equipment for data collection but had higher associated expenses for laboratory consumables and data processing. We recommend the use of both methods for northern muriqui monitoring and provide suggestions for improving the implementation of these non-invasive methods for future routine monitoring. Our findings also highlight the potential of arboreal camera trapping and genetic tagging to other arboreal mammals in tropical forests.

  PublisherDOI

Recent grants

• Niche Expansion and Terrestriality in an Arboreal Primate

  NSF · $309k · 2009–2014

Frequent coauthors

• Sérgio Lucena Mendes

  Instituto Nacional da Mata Atlântica

  43 shared

• Susan C. Alberts

  Duke University

  30 shared

• Jeanne Altmann

  26 shared

• Fabiano Rodrigues de Melo

  Universidade Federal de Viçosa

  26 shared

• Marina Cords

  Columbia University

  22 shared

• Jean P. Boubli

  University of Salford

  21 shared

• Anne E. Pusey

  21 shared

• Tara S. Stoinski

  The Dian Fossey Gorilla Fund International

  21 shared