Primates at Risk: Conservation Concerns and Anthropogenic Landscapes
Chaired by:
 Kevina Vulinec, Department of Agriculture and Natural Resources, Delaware
State University
 Kathryn E. Stoner, Centro de Investigaciones en Ecosistemas, Universidad
Nacional Autónoma de México
In this symposium we present papers on the current knowledge of primates and
anthropogenic disruption of the landscape. We concentrate on landscapes in the
Americas. Of particular interest is how primates are reacting in terms of populations and
behavior to different land use patterns over landscape levels. This group of papers
explores current research in primate conservation in reference to human land use patterns,
including that by indigenous people. These patterns include fragmentation, but also land
use as different management regimes by local and indigenous people. These land
practices include hunting, agriculture, and development.
Fear and loathing in the rainforest: hunting and primate behavior in
the Americas
Kevina Vulinec and David Mellow
Delaware State University, Dover, Delaware, USA
Email: kvulinec@desu.edu
Hunting affects primate behavior and population size by the direct killing of adults and
through indirect effects on behavior. Certain primates, including the adaptable Alouatta
spp. in hunted areas have smaller troop sizes, evince avoidance behavior, and the
presence of humans alone may disrupt normal activities. Other primates in the same
areas, particularly smaller, less hunted species, react less fearfully to the presence of
humans. We summarize over 10 years of primate surveys from areas with differing
hunting pressure in the Brazilian Amazon and discuss the effect of hunting on behavior,
troop size, and density.
Keywords: Primates; hunting; behavior; populations
Spider monkeys (Ateles geoffroyi) in small reserves: can mutualistic
interactions between large monkeys and large seeded plants be
maintained in the Osa Peninsula, southwestern Costa Rica?
Pablo Riba Hernández1 and Kathryn E. Stoner2
1
Universidad de Costa Rica, Escuela de Biología, San José, Costa Rica
2
Centro de investigaciones de Ecosistemas, Universidad Nacional Autónoma de México
Email: proyectocarey@yahoo.com.mx, kstoner@oikos.unam.mx
Spider Monkeys (Ateles) are the largest Neotropical specialized frugivores capable of
dispersing large seeds. Due to anthropogenic actions, the Osa Peninsula in southwestern
Costa Rica has been fragmented into small islands with only a few protected areas. It is
unknown to what extent mutualistic interactions, such as seed dispersal of large seeds by
monkeys, are maintained within these small protected reserves. We evaluate the status of
Ateles geoffroyi as seed dispersers in the tropical rainforest at Punta Rio Claro Wildlife
Refuge (500 ha; 90% mature forest). If this small reserve is successful in maintaining the
mutualistic interactions offered by Ateles we expected: 1) large-seeded plants will be
included in their diet, 2) most fruits consumed will result in seed dispersal, 3) foraging
will occur mainly in mature forest, and 4) monkeys will be present year around within the
reserve. Ateles consumed fruits from 52 of the 70 tree species reported for the reserve.
Their diet included 30% large-seeded species, with all species being swallowed and
dispersed. Large-seeded tree species were the most important in their diet. Approximately
90 % of their foraging time occurred in primary forest. Although it appears as if the
mutualistic interaction of seed dispersal by Ateles is maintained within this small reserve,
monkeys were not found year around, being absent in the months coinciding with the
lowest fruit availability. These results suggest that 500 ha may not be big enough to
sustain local populations of Ateles within the region. Their absence within small
fragments, even for part of the year, may have consequences for the regeneration of
large-seeded plants and ultimately effect forest structure and composition. We suggest
that conservation efforts within the region focus on preserving larger fragments of mature
forest to ensure the maintenance of mutualisitc interactions between large-seeded plants
and their dispersers.
Keywords: frugivory, mutualism, fragmentation, primates
Presence of black howler monkeys (Alouatta pigra) and regeneration in
tropical rain forest fragments in the Lacandon region, Chiapas, Mexico
Ana Marie González di Pierro, J ulieta Benítez-Malvido, and Kathryn E. Stoner
Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México
Email: dipierro@oikos.unam.mx
Primates are known to be important seed dispersers for many tropical plant species.
Although Howler monkeys (Alouatta spp.) are classified as folivores based on their
annual diet, it has been well documented that they consume a great variety of fruits.
Because of their dietary plasticity and flexible social structure, howler monkeys are often
found in perturbed habitats, making them a potentially important factor in the
regeneration of forest fragments. We evaluate the importance of Alouatta pigra in seed
dispersal and fragment regeneration by documenting species of plants dispersed by
howlers and determining the effect of seed ingestion on germination. Furthermore we
compare tree species richness, seedling richness, and seedling establishment in
continuous forest, fragments with monkeys, and fragments without monkeys. The study
was conducted in the tropical wet forest of Lacandona region, Chiapas, in southeastern
Mexico. Howler monkeys dispersed seeds from 24 species in the continuous forest and
16 in forest fragments. Ingestion had a positive effect on germination in three (Dialium
guianensis, Garcinia intermedia and Tetracera sp.) of the six species evaluated. No
significant differences were observed in tree species richness among fragments with
monkeys, without monkeys and continuous forest. Nevertheless, a significantly lower
importance value of species dispersed by howlers was found in fragments without
monkeys. Seedling richness and seedling establishment was greater in fragments with
howlers than in those without. Overall, the presence of howler monkeys appears to
positively influence forest regeneration in tropical rain forest fragments in the
Lancandona region.
Keywords: Howler monkey, seed dispersal, germination, regeneration forest
The influence of large tree density on Howler Monkey (Alouatta palliata
mexicana) presence in very small rainforest fragments
Arroyo-Rodriguez Victor(1), Mandujano Salvador(1), Benitez-Malvido Julieta(2),
1
Instituto de Ecologia A.C.
2
Centro de Investigacion en Ecosistemas, UNAM
email: victorarroyo_rodriguez@hotmail.com
The populations of the Mexican mantled howler monkey (Alouatta palliata mexicana) in
the Los Tuxtlas region, Mexico, have declined drastically due to habitat loss and
fragmentation. Nevertheless, several troops still inhabit very small and isolated rainforest
fragments. We identified the main vegetation attributes that can favour the presence of
howlers within 18 small (< 10-ha) fragments that did not differ significantly in size,
shape and isolation (nine occupied and nine unoccupied by howlers). We found that
habitat quality (i.e., food resources and vegetation structure) affected howler incidence in
small fragments. Particularly, the occupied fragments showed greater density of big trees
(DBH > 60 cm), greater total basal area, greater basal area of persistent tree species and
greater basal area of top food species than the unoccupied fragments; suggesting that
even for small fragments the loss of big trees and particularly the decrease in size class of
the top food species can negatively affect howler distribution in highly fragmented
landscapes. These findings could be used to establish foreground conservation areas for
this critically endangered subspecies in fragmented landscapes of Los Tuxtlas.
keywords: fragmentation, habitat quality, Los Tuxtlas, Mexican mantled howler
monkeys, Mexico
Patterns of distribution and persistence in a degraded landscape: a
primate community in the Brazilian Amazon
Sarah A. Boyle1, Kellen A. Gilbert2, , Wilson R. Spironello, Alaercio Marajó dos
Réis3, Osmaildo Ferreira da Silva3, Waldete Castro Lourenço3 and Lívia Rodrigues
da Silva3
1
Arizona State University, Tempe, Arizona, USA
2
Southeastern Louisiana University, Hammond, Louisiana, USA
3
Instituto Nacional de Pesquisas da Amazonia, Manaus, Brazil
Email: Sarah.Boyle@asu.edu
We present the findings of more than two decades of primate census data in nine forest
fragments in upland terra firme forest in central Amazonia. Forest fragments varied in
size and distance to closest forested area, and the condition of the surrounding
agricultural matrix ranged from pasture to high secondary growth forest. Furthermore, the
six primates species present in the study area varied in body size, home range
requirements, and diet. We found differences in primate species composition and
distribution across the fragmented landscape, and the persistence of the species in the
fragments varied throughout the two decades. While some species (Alouatta seniculus)
fared well in the fragmented landscape and were present in fragments as small as 1ha,
other species (Ateles paniscus) were rarely present in the fragments. We discuss the
implications of these ecological and behavioral differences for primate conservation in
agricultural areas.
Keywords: primates, forest fragmentation, conservation
Human dimension of primate conservation issues in tropical countries
and conservation value of some current, traditional and alternative land
management practices from Mesoamerica
Alejandro Estrada, Genoveva Trejo and Cristina Jasso
Estación de Biología Tropical Los Tuxtlas, Instituto de Biología, Universidad Nacional
Autónoma de México
Email: aestrada@primatesmx.com
Pressures for land use have been pointed out as the major cause of tropical rain forest loss
and fragmentation throughout the world, and a major cause of increases in rates of
species extinction in recent decades. The high primate diversity found in the Neotropics,
Africa and Asia makes these regions one of the world’s greatest conservation challenges.
In this paper we examine several aspects of the human dimension of the conservation
problem of primates and their habitats in these three regions. We specifically review
available data on human population growth trends, levels of poverty, major land use
patterns as they relate to food production, and deforestation rates and trends. We
additionally inspect the PrimateLit database to generally assess the richness of our data
banks on the basic biology, ecology and behavior of primate taxa for the three geographic
regions of interest. We further examine regional conservation initiatives and their
possible impact upon the persistence of primate habitats. Finally, using a landscape
approach, we look at some current, traditional and alternative land management practices
in Mesoamerica as possible conservation scenarios of primate populations in humanmodified landscapes.
Keywords: Mesoamerica, deforestation, poverty, traditional land-use, tropical rain forest
conservation