Movements of a wild night monkey (Aotus trivirgatus) -- Overview of the Mesoamerican Primate Fauna, Primate Studies, and Conservation Concerns -- Taxonomy and Biogeography -- Introduction: Taxonomy and Biogeography -- Taxonomy and Distributions of Mesoamerican Primates -- The Biogeographic History of Mesoamerican Primates -- Population Responses to Disturbance -- Introduction: Population Responses to Disturbance -- Demographic Features of Alouatta pigra Populations in Extensive and Fragmented Forests -- Population Structure of Black Howlers (Alouatta pigra) in Southern Belize and Responses to Hurricane Iris -- The Effects of Forest Fragment Age, Isolation, Size, Habitat Type, and Water Availability on Monkey Density in a Tropical Dry Forest -- Forest Fragmentation and Its Effects on the Feeding Ecology of Black Howlers (Alouatta pigra) from the Calakmul Area in Mexico -- Intestinal Parasitic Infections in Alouatta Pigra in Tropical Rainforest in Lacandona, Chiapas, Mexico: Implications for Behavioral Ecology and Conservation -- Behavior and Ecology -- Introduction: Behavior and Ecology -- Average Body Weight for Mantled Howling Monkeys (Alouatta palliata): An Assessment of Average Values and Variability -- An Exploratory Analysis of Developmental Plasticity in Costa Rican Mantled Howler Monkeys (Alouatta palliata palliata) -- Travel Patterns and Spatial Mapping in Nicaraguan Mantled Howler Monkeys (Alouatta palliata) -- Use of Landmark Cues to Locate Feeding Sites in Wild Capuchin Monkeys (Cebus capucinus): An Experimental Field Study -- Leap, Bridge, or Ride? Ontogenetic Influences on Positional Behavior in Cebus and Alouatta -- Food Choice by Juvenile Capuchin Monkeys (Cebus capucinus) in a Tropical Dry Forest -- Why Be Alpha Male? Dominance and Reproductive Success in Wild White-Faced Capuchins (Cebus capucinus) -- Post-conceptive Mating in White-Faced Capuchins, Cebus capucinus: Hormonal and Sociosexual Patterns of Cycling, Noncycling, and Pregnant Females -- Conservation and Management Policies -- Introduction: Conservation and Management Policies -- Growth of a Reintroduced Spider Monkey (Ateles geoffroyi) Population on Barro Colorado Island, Panama -- Primates in Agroecosystems: Conservation Value of Some Agricultural Practices in Mesoamerican Landscapes -- Primate Populations in the Protected Forests of Maya Archaeological Sites in Southern Mexico and Guatemala -- Mapping Primate Populations in the Yucatan Peninsula, Mexico: A First Assessment -- A Metapopulation Approach to Conserving the Howler Monkey in a Highly Fragmented Landscape in Los Tuxtlas, Mexico -- Quantifying Fragmentation of Black Howler (Alouatta pigra) Habitat after Hurricane Iris (2001), Southern Belize -- Synopsis and Perspectives -- New Perspectives in the Study of Mesoamerican Primates: Concluding Comments and Conservation Priorities. The purpose of this volume is to present a comprehensive overview of recent advances in primate field research, ecology, and conservation biology in Mesoamerica. The overall goal of each contribution is to integrate newly collected field data with theoretical perspectives drawn from evolutionary biology, socioecology, biological anthropology, and conservation to identify how our current knowledge of primate behavior and ecology has moved beyond more traditional approaches. A corollary to this, and an important goal of the volume is to identify geographical regions and species for which we continue to lack sufficient information, to develop action plans for future research, and to identify areas for immediate conservation action. Despite many decades of primate research in Mesoamerica, much is still unknown concerning the basic ecology and behavior of these species, demography, current distribution, and conservation status of local populations, and the effectiveness of conservation policies on primate survivorship. Four major areas of research are the focus of the volume: Evolutionary Biology and Biogeography; Population Demography and Ecology; Behavior; and Conservation and Management Policies.