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We analysed the selection of tree species consumed by an isolated troop of Mexican howler monkeys (Alouatta palliata mexicana) released in a translocation programme on Agaltepec Island, in Catemaco Lake, Veracruz, Mexico. During November 1989–December 1996, howlers used 36 of the 63 tree species present on the island as food. Selection ratios indicated that six Ficus species (particularly F. pertusa) were among the seven most important food species. Data on time spent feeding showed that the six Ficus species were among the eight most important food species for the monkeys. Howlers spent 64.2% of their feeding time on Ficus products with F. pertusa being consumed significantly more often than foods from other Ficus species. However, monkeys fed on only one third of the 81 adult Ficus trees on the island. No significant differences were found in various food constituents (water, ash, fibre, protein, carbohydrates, lipids) of the six Ficus and two other abundant species in the habitat, whether across species, plant parts (young leaves, mature leaves, fruits), or between seasons (wet, dry). Monkeys consumed Ficus fruits rather the leaves. Fruits showed a much higher energy content per g dry weight than leaves. We also estimated the average daily biomass of leaves and fruits of Ficus spp. consumed by howlers and their energetic contribution to the daily diet of these monkeys. We suggest that some of these tendencies to frugivory reflect the abundance of Ficus trees within the home ranges of the howlers; when few fig trees are present, folivory is the dominant tendency, whereas when many fig trees are present, frugivory is dominant.

We studied changes in germination rates and dispersal distance of seeds of Ficus perforata and F. lundelli dispersed by howler monkeys (Alouatta palliata mexicana), in a small (40 ha) ‘disturbed’ and a larger (>600 ha) ‘preserved’ tropical rainforest in southern Veracruz, Mexico. The interaction between A. p. mexicana and Ficus (Urostigma) spp. is beneficial for the interacting species and has important implications for their conservation. Howler monkeys gain from the ingestion of an important food source, germination rates of Ficus seeds are improved by passage through the monkeys' digestive tract, and the seeds are more likely to be deposited in a site suitable for germination and development. Seed dispersal distances are relatively larger in the preserved site, with both the size of the forest area and the spatial pattern of Ficus affecting the dispersal process. In a large forest fragment with ‘regularly’ distributed Ficus individuals the howler monkeys move away from the seed source, increasing the probability that the seeds are desposited on a tree other than Ficus, which is important for the germination and future development of a hemiepiphytic species. In a small forest fragment with trees distributed in clumps howlers repeatedly use the same individual trees, and faeces containing seeds may be dropped on unsuitable trees more often. These are key issues when addressing conservation policies for fragmented forests.

This study seeks to understand children's perceptions and knowledge of endangered Mexican primates. The black howler monkey (Alouatta pigra) is a charismatic species endemic to Southern Mexico, Northern Belize, and Guatemala and is a symbol of the region that fosters a sense of local pride. Therefore, it can be considered a flagship species for the forests of Southern Mexico. We evaluated the perception and knowledge that 297 Mexican elementary school children (8-10 years old) have about black howler monkeys. Specifically, we analyzed and categorized drawings made by these children based on gender, geographic context (rural or urban), and residence within or outside of Protected Areas (PAs). Student drawings were categorized into three levels of knowledge (no familiarity, basic knowledge, and sophisticated knowledge). Common misconceptions and important landscape elements for black howler conservation were gathered from these visual representations. Children were largely unfamiliar with black howlers, despite sharing the same geographical location. Knowledge was affected by context and residence, with students living within PAs more aware of black howlers than students living outside of PAs. However, overall the children showed a deep understanding of the current forest conservation situation in Southern Mexico; meaning they could be presenting a shifting baseline syndrome. The study highlights the value of assessing children's drawings as a tool that can be used to help policy makers and educational practitioners in fine-tuning educational, environmental, and marketing programs. More importantly, it is a methodology that can be applied in future research for understanding children's perceptions and knowledge about endangered species and environmental change in deciding how to improve the effectiveness of conservation messaging.

In this chapter, we review how anthropogenic disturbance specifically impacts members of the genus Alouatta, one of the most geographically expansive and ecologically flexible of platyrrhine groups. This report initiates with a brief discussion of the use of matrix landscapes, the effects of ecotourism, and the potential for crop-raiding by howler monkeys. We then present three case studies of howler monkey responses to these challenges. We found that tourism in Suriname leads to greater travel and foraging time and poorer health for A. macconnelli. A. palliata in Costa Rica living in an agricultural matrix respond to habitat modification through active crop-raiding, and A. pigra in Mexico provide an illustration of how to evaluate remnant monkey populations for potential ecotourism. The chapter concludes with recommendations for encouraging shared landscapes with howler monkeys, including ways to minimize crop damage by monkeys and ways to encourage sustainable, conservation-based ecotourism.

To construct informed conservation plans, researchers must go beyond understanding readily apparent threats such as habitat loss and bush-meat hunting. They must predict subtle and cascading effects of anthropogenic environmental modifications. This study considered a potential cascading effect of deforestation on the howler monkeys (Alouatta pigra) of Balancan, Mexico. Deforestation intensifies flooding. Thus, we predicted that increased flooding of the Usumacinta River, which creates large bodies of water that slowly evaporate, would produce increased lead content in the soils and plants, resulting in lead exposure in the howler monkeys. The average lead levels were 18.18 ± 6.76 ppm in the soils and 5.85 ± 4.37 ppm in the plants. However, the average lead content of the hair of 13 captured howler monkeys was 24.12 ± 5.84 ppm. The lead levels in the animals were correlated with 2 of 15 blood traits (lactate dehydrogenase and total bilirubin) previously documented to be associated with exposure to lead. Our research illustrates the urgent need to set reference values indicating when adverse impacts of high environmental lead levels occur, whether anthropogenic or natural, and the need to evaluate possible cascading effects of deforestation on primates.

Recent evidence has shown that primates worldwide use agroecosystems as temporary or permanent habitats. Detailed information on how these primates are using these systems is scant, and yet their role as seed dispersers is often implied. The main objective of this study was to compare the activity, foraging patterns and seed dispersal role of black howler monkeys (Alouatta pigra) inhabiting shaded cocoa plantations and rainforest in southern Chiapas, Mexico. We gathered data on three monkey groups living in shaded cocoa plantations and three groups living in rainforest, using focal sampling, and collecting fecal samples. General activity and foraging patterns were similar in both habitats, with the exception that monkeys in the cocoa habitat spent more time feeding on petioles. Monkeys in shaded cocoa plantations dispersed 51,369 seeds (4% were seeds ≥3 mm width) of 16 plant species. Monkeys in the rainforest dispersed 6,536 seeds (78% were seeds ≥3 mm width) of 13 plant species. Our data suggest that the difference between habitats in the proportion of large versus small seeds dispersed reflects differences in fruit species abundance and availability in cocoa versus forest. Mean seed dispersal distances were statistically similar in both habitats (cocoa = 149 m, forest = 86 m). We conclude that the studied cocoa plantations provide all elements necessary to constitute a long-term permanent habitat for black howler monkeys. In turn, howler monkeys living in these plantations are able to maintain their functional role as seed dispersers for those native tree and liana species present within their areas of activities.

Recently several studies have focused on the structure of ecological networks to provide insights into ecological and coevolutionary dynamics of interacting species. However, rarely have the tools of ecological networks been used to understand how feeding relationships vary among individuals of the same population. Here we use 7 years of data and network analyzed to examine the intrapopulation diet variation in a group of howler monkeys (Alouatta palliata). We show that individual monkey-resource food webs are nested, but not modular and the stability of these patterns is independent of time of day or season. Our findings indicated that individuals do not forage randomly when compared to null models and that the diets of more selective monkeys represent subsets of the diets of other individuals. Moreover, there are no subgroups that eat a particular set of available plant species more frequently than other sets, suggesting that the spatial strategy of group foraging plays an important role in the feeding ecology of each group given that individuals of the same group tend to share similar resources while the group remains at a feeding site. Since the diets of more selective individuals are a subset of other monkeys, we suggest that more selective monkeys are able to outcompete others for preferred foods. Additionally, we did not observe differences in nutritional content or spatial abundance of more frequently eaten plant species when compared with less frequently eaten species, but in most cases, the more frequently eaten plant species were Ficus (Moraceae). This reinforces the important role that Ficus trees play in howler monkey feeding ecology, likely due to its year-round availability.

In 2010, the Food and Agriculture Organization of the United Nations (FAO) estimated that 16 million hectares of forest per year were lost globally in the 1990s (FAO 2010), and approximately 12.5 million hectares/year were lost in countries with primate populations, an area just smaller than Greece or the US State of Mississippi (Chapman and Peres 2001; Chapman and Gogarten 2012). In contrast, in the last decade (2000–2010), the rate of deforestation has decreased globally by approximately 5.2 million hectares/year, and reforestation and natural expansion of forests in some countries significantly reduced the net loss of forest (FAO 2010). This may be in part due to the lack of resonance in satellite imagery between secondary and primary forest regions, particularly in the tropics. Unfortunately, the increase in forested lands has principally affected temperate regions of Europe and eastern Asia (e.g., China, Japan), but deforestation of most tropical forests has continued steadily (e.g., annual loss: 0.5 % in Africa, 1.2 % in Mesoamerica, 0.5 % in South America, 0.4 % in southeastern Asia; FAO 2011).

The distribution of primate species, under current and climate change scenarios, constitutes crucial information for their successful conservation. In areas with limited information on their distribution, simple extrapolations based on historical records may not reflect the actual distribution of a species. Here we model the potential distribution, under a current and a climate change scenario for the year 2020, of the two species of ateline primates that inhabit the Yucatan peninsula, in Mexico: spider (Ateles geoffroyi) and howler monkeys (Alouatta pigra). Data from a recent survey in 78 locations throughout the Yucatan peninsula were used as inputs for the DOMAIN algorithm, which estimates the similarity between the predictor variables found in the surveyed locations and those in the potential range of the species. The distributions estimated using this algorithm can be considered as being similar to the surveyed locations with a given degree of certainty (in this case, we used thresholds of 95, 97, and 99 %). We have used two different strategies for estimating the potential distribution of howler and spider monkeys in the Yucatan peninsula. The first strategy employed biophysical variables as predictors and obtained areas of potential distribution for both species that range from 19 to 81 % of the region’s extent, depending on the threshold. The second strategy began by using the same biophysical variables to generate potential distributions for important trees in the diet of both primates, and then used the similarity values thus obtained as predictors of the potential distribution of monkeys. This strategy yielded somewhat smaller areas with similarity values above the threshold, comprising between 11 and 75 % of the region’s extent. Semievergreen forest, the most abundant original vegetation cover in the Yucatan peninsula, was not the most abundant vegetation within the potential distribution areas, although it became more important as the threshold of habitat similarity was increased from 95 to 99 %. Protected areas, particularly the Calakmul Biosphere Reserve, include a small proportion (between 8 and 18 %, depending on the species, predictor variables and similarity threshold) of the species’ potential distribution. Climate change scenarios predict a slight increase in the extent of similar habitat for both species in 2020, particularly in the south-central portion of the peninsula. Less than 20 % of the extent of potential distribution under current and climate change scenarios lies within protected areas. For both species, the largest extent with similarity values >97 % lies in the northeastern Yucatan peninsula, an area with little protection, subject to high pressures for development and that could become less hospitable for both primate species under a climate change scenario.

Animals' responses to potentially threatening factors can provide important information for their conservation. Group size and human presence are potentially threatening factors to primates inhabiting small reserves used for recreation. We tested these hypotheses by evaluating behavioral and physiological responses in two groups of mantled howler monkeys (Alouatta palliata mexicana) at the "Centro Ecológico y Recreativo El Zapotal", a recreational forest reserve and zoo located in the Mexican state of Chiapas. Both groups presented fission-fusion dynamics, splitting into foraging subgroups which varied in size among, but not within days. Neither subgroup size nor number of people had an effect on fecal cortisol. Out of 16 behavioral response variables tested, the studied factors had effects on six: four were affected by subgroup size and two were affected by number of people. With increasing subgroup size, monkeys increased daily path lengths, rested less, increased foraging effort, and used more plant individuals for feeding. As the number of people increased, monkeys spent more time in lower-quality habitat, and less time engaged in social interactions. Although fecal cortisol levels were not affected by the factors studied, one of the monkey groups had almost twice the level of cortisol compared to the other group. The group with higher cortisol levels also spent significantly more time in the lower-quality habitat, compared to the other group. Our results suggest that particular behavioral adjustments might allow howler monkeys at El Zapotal to avoid physiological stress due to subgroup size and number of people. However, the fact that one of the monkey groups is showing increased cortisol levels may be interpreted as a warning sign, indicating that an adjustment threshold is being reached, at least for part of the howler monkey population in this forest fragment.

Composition of the landscape matrix of surrounding forest fragments is thought to be critically important to the survival of arboreal primates because it offers structures that help the animals move between fragments and other foraging sites. However, little is known about the composition of the matrix used by these animals. The aim of this study was to quantitatively assess the importance of the landscape matrix and its effects on primate abundance, using black howler monkeys (Alouatta pigra) living in a landscape fragmented by the expansion of agriculture and pastures for livestock in southeastern Mexico. In 2008, a complete census of the monkeys was carried out across the 2000-ha landscape matrix, and for every site where we observed monkeys, we recorded canopy height, tree basal area, food-source abundance, and distance to the nearest fragment. A total of 244 howler monkeys, distributed among 48 groups (including six solitary males) were counted in the matrix. Mean troop size was 5.6 ± 2.8 individuals, and the mode was three individuals. The highest number of troops and greatest howler monkey abundance were recorded in the isolated trees, the eucalyptus plantation, and orchards. A generalized linear model revealed that monkey abundance tended to be higher in matrix elements with higher canopy height, greater food availability, and closest to rainforest fragments. These results suggest that it is necessary to take into account the many elements of the landscape when drawing up conservation and habitat management plans, particularly in order to establish connectivity among the fragments and elements of the matrix with native trees.

We evaluated the habitat and populations of the black howler monkey (Alouatta pigra) in the municipality of Balancan, Tabasco, southeastern Mexico, using a combination of field surveys and remotely sensed data. We identified 21,937 ha of remnant vegetation composed of 1,348 fragments. Fragments separated by up to 200 m were grouped into "clusters" of fragments in accordance with the maximum observed open distance crossed by A. pigra. A total of 11% or 84 of the 772 clusters identified through remote sensing were selected at random, and for these we determined the vegetation type, canopy height, area, and distance to the closest human settlement. In these same 84 clusters, which included a total area of 9,817 ha, from October to June of 2006 we located a total of 1,064 black howler monkeys, including 228 troops and 49 solitary monkeys. A. pigra was found in 62 (74.7%) of all clusters visited, with a cumulative area of 6,032 ha. Troops varied in size from 2 to 15 individuals (average 6.0+/-2.9 ind/troop). Adults were 67% (n=716) of detected individuals, whereas juveniles were 20.5% (n=218) and infants were 12.5% (n=133). We found black howlers to occur at an ecological density of 10.8 ind/km(2), which is low in comparison with A. pigra in other fragmented and conserved sites. We found a statistically significant relationship between the area of clusters and the abundance of howler monkeys (r(2)=0.2, F=10.47, gl=3, P=0.002). In addition, the probability of finding A. pigra was greater in secondary vegetation, riparian vegetation, tropical dry forest, undisturbed tropical oak forest, and palm forest (F=12, gl=3, P

There continue to remain uncertainty concerning the nutritional importance of figs (Ficus spp.) in the primate diet. Although studies have been performed on the nutritional analysis of fig pulp and seed fractions separately, there has not been an attempt to quantify the contribution of animal matter within figs. Here we report nutritional values of figs (Ficus perforata) (Urostigma) consumed by a troop of howler monkeys (Alouatta palliata mexicana). Separate nutritional assays were performed on the pulp, seed, and animal fraction. Whole-fig analyses significantly exaggerate the concentrations of all nutrients (lipids especially) as seeds, which represent a large proportion of the fig (45%), cannot be digested. Animal matter only represents 1% of the fig, and augments fig protein and lipid content by 0.44 and 0.30%, respectively. This represents the 11 and 9% of the fraction available for digestion. Differences in fig consumption were observed between age and sex classes (P=0.04) and periods of the day (P=0.001); females consumed more figs than males and the highest consumption of figs was observed in the afternoon. F. perforata figs may be an important component of the howler monkeys diet owing to their high content of water and calcium.

This study evaluates the popularity and economic impact of Las Islas de los Changos (the Monkey Islands) as an ecotourism site on Lake Catemaco in the Los Tuxtlas region of Veracruz, Mexico. Two small island colonies of exotic primates, stumptail macaques (Macaca arctoides), have proved to be highly beneficial for the local economy as the main attraction for tourists in this region. From July 1991 to June 1992, data were collected on the number of tourists who took boat trips to visit the primates, and the amount of money spent on tours to the islands. The data suggest that at least 28,470 passengers visit these primate troops annually and spend approximately 88,970 U.S. dollars (USD). Follow-up questionnaires during July 1997 to June 2000 to hotelkeepers and tourist boat operators identified the Monkey Islands as the primary destination for tourists to this region. A comparison of the net income obtained by local ecotourism operators with wages earned through other types of employment in the Los Tuxtlas region, such as working in natural reserves, agriculture, or renting grazing land for cattle, show the relative importance of Las Islas de Los Changos in sustaining the local economy.

Recent studies suggest that the identification of interactions among keystone species in ecosystems is one of the most important aspects to be considered in conservation programs (Thompson, 1994; Howe and Miriti, 2000). We also need to evaluate how interspecific interactions are modified by habitat fragmentation and destruction (Nathan and Muller-Landau, 2000), which will provide information required to make informed policy decisions regarding conservation and forest management (Garber and Lambert, 1998). In this chapter, we address the effects of habitat fragmentation on the regeneration dynamics of tropical rain forests, particularly the ecological interactions among strangler figs (Ficus spp.: Moraceae) and Mexican howler monkeys (Alouatta palliata mexicana) in southeastern Mexico.

A variety of microclimatic factors influence the success of seed germination in the strangler figs Ficus perforata and F. lundelli consumed by howler monkeys (Alouatta palliata mexicana) in southern Veracruz, Mexico. Seed germination was compared at two canopy heights in two different study sites: disturbed (Playa Escondida; 40ha) and preserved (Carolino Anaya Reserve, Coatzacoalcos; 600ha). Germination varied depending on canopy height where the seeds were placed, and the quality (degree of conservation) of the habitat (preserved or disturbed). There was an evident between-habitat variation in humidity, light intensity, and temperature in the host trees for hemiepiphytic Ficus, which may affect the percent of germination response. The results show higher germination at the highest canopy location for seeds of both species. Germination was significantly higher in the preserved site for seeds from feaces vs. seeds from fruits source. The latter is probably the effect on seed germination of the higher relative humidity and low light and temperature levels in the preserved site. Diversos factores microclimáticos influyen en el éxito de la germinación de semillas de Ficus estranguladores (F. perforata y F. lundelli) consumidas por monos aulladores (Alouatta palliata mexicana) en el sureste de Veracruz, México. La germinación de semillas de estas especies fue comparada entre dos estratos arbóreos en dos diferentes sitios de estudio: perturbado (Playa Escondida; 40ha) y conservado (Reserva Carolino Anaya, Coat-zacoalcos; 600ha). Los resultados muestran que la germinación varió con el estrato arbóreo donde fueron depositadas las semillas y con la calidad (grado de conservación) del hábitat (conservado o perturbado). Bajo estas diferentes condiciones de hábitat, fueron evidentes las variaciones en humedad, intensidad de luz y temperatura de los árboles hospederos para los Ficus hemiepífitos, que podrían estar afectando el porcentaje de germinación. Se registró mayor germinación de ambas especies en los estratos superiores. La germinación fue significativamente mayor en el sitio conservado para las semillas que provenían de las heces contra aquellas no dispersadas de esta manera. Esto último es, probablemente, resultante de una mayor humedad relativa y bajos niveles de luz y temperatura que influyen positivamente en la germinación en el sitio conservado. Diversos fatores microclimáticos influem no êxito da germinação de sementes de Ficus estranguladores (F. perforata y F. lundelli) consumidas por macacos uivadores (Alouatta palliata mexicana) no sudeste de Veracruz, México. A germinação de sementes destas espécies foi comparada entre dois extratos arbóreos nos dois diferentes lugares de estudo: perturbado (Playa Escondida; 40ha) e conservado (Reserva Carolino Anaya, Coatzacoalcos; 600ha). Os resultados mostram que a germinação variou com o extrato arbóreo onde foram depositadas as sementes e com a qualidade (grau de conservação) do habitat (conservado ou perturbado). Sob estas diferentes condições de habitat, foram evidentes as variações em umidade, intensidade de luz e temperatura das árvores hospedeiras para os Ficus hemiepífitos, que poderiam estar afetando a percentagem de germinação. Registrou-se maior germinação de ambas espécies nos extratos superiores. A germinação foi significativamente maior no lugar conservado para as sementes que provinham das fezes em vez daquelas não dispersadas desta maneira. Este último é, provavelmente, resultante de uma maior umidade relativa e baixos níveis de luz e temperatura que influem positivamente na germinação no lugar conservado.

We analyzed Ficus perforata seed removal by canopy ants under four treatments: syconia seeds; howler monkey-defecated washed seeds; syconia seeds with howler dung; and defecated seeds with howler dung. Ants removed more defecated washed seeds in the wet season, while during the dry season, removal was greater for syconia seeds and defecated washed seeds. Our results suggest that ants tended to remove more seeds when they were not embedded in feces; however, even seeds set on howler dung were still attractive to ants.