Population Of Black Howler Monkeys Research Articles

Effects of anthropogenic stress on the presence of parasites in a threatened population of black howler monkeys (Alouatta pigra)

Habitat disturbance disrupts the ecological interactions of mammals, leading to negative consequences for biodiversity. In particular, it is suggested that parasite-host interactions are affected in tropical ecosystems, with parasite diversity reduced as environmental perturbations take place. In this study, we examined whether the disruption of tropical forests affects the presence of parasites in a population of endangered black howler monkeys (Alouatta pigra) that inhabits a highly fragmented landscape in Balancan, Tabasco, Mexico. Our working hypothesis was that increased forest perturbation would negatively affect the incidence of parasitic infections (parasite presence and richness) in black howler monkeys. We conducted a parasitological study and collected stool samples from 65 adult individuals living in 30 forest fragments across a disturbance gradient. We recovered parasite eggs from stool samples using flotation and sedimentation techniques. We selected fragment size and distance from each forest fragment to the nearest village as measures of forest perturbation. We analyzed the effects of forest perturbation on parasite presence and richness using generalized linear models. Other driving factors such as seasonality, host density, and sex were also considered in the models. Gastrointestinal parasite infection was positively related to distance between forest fragments and the nearest human settlement (β = 0.55 ± SE 0.28, z = 2.0, P = 0.05). No effects of fragment size or any other variable considered in the model on the presence of parasite infection were observed. Parasite richness was not affected by any of the measures of forest perturbation, nor by any other variables considered in the analysis. Our findings suggest that an increase in forest perturbation may negatively affect the probability of parasite infection in black howler monkeys, as individuals living in close proximity to human settlements showed a lower presence of parasites. We proposed that the low parasite infection rates recorded in this monkey population reflect synergistic effects associated with both the alteration of the parasite-primate network, as well as the low resilience of parasites to thrive in a disrupted ecosystem.

Kin-biased spatial associations and social interactions in male and female black howler monkeys (Alouatta pigra)

Kinship has been shown to play a crucial role in shaping the social structure of animal societies. We examined the genetic relationships of adult and sub-adult males () and females () from five social groups of black howler monkeys (Alouatta pigra) at Palenque National Park, Mexico, by genotyping each individual at 21 microsatellite markers. These findings were related to patterns of intragroup spatial associations and affiliative and agonistic interactions recorded over a 28-month period of behavioural observation in the field. We demonstrate that the social structure of this black howler monkey population is dominated by strong social relationships and high degrees of genetic relatedness among females. Female kin had stronger relationships because they were less aggressive to each other than female non-kin. Nevertheless, females resident in the same social group frequently spent time close to one another and affiliated with each other regardless of kinship. Relationships among males from the same social group were based on avoidance and tolerance, as males rarely interacted either affiliatively or agonistically and spent limited time close to one another. Nonetheless, kinship was a significant predictor of agonistic interactions among males, with unrelated or distantly related males engaging in agonism at higher rates than close male kin. Adult males and females rarely co-resided with adult kin from the opposite sex, and they affiliated and spatially associated at rates intermediary to those among females and those among males.

The interacting roles of food availability, stress and parasitism in determining black howler monkey population density following a major hurricane

The interacting roles of food availability, stress and parasitism in determining black howler monkey population density following a major hurricane

The Role of Minerals in Food Selection in a Black Howler Monkey (Alouatta Pigra) Population in Belize Following a Major Hurricane

As plants may contain low levels of some minerals including sodium, copper, and phosphorous, herbivores may become deficient in these nutrients. In 2001, Hurricane Iris hit the Monkey River Forest in Belize causing substantial damage to the food supply of the black howler monkey population (Alouatta pigra) living there. This included an 18-month absence in fruit production and a complete loss of figs that are high in calcium. In this article, we describe the post-hurricane diet of this monkey population and compare the mineral content of food items to each other and to recommendations for non-human primates [NRC 2003]. We also investigate food selection in relation to potentially limiting minerals. Behavioral data from four groups of howlers (2002-2006) and samples of all ingested food items were collected and a sample of 99 plant from 18 food species was analyzed for mineral content. Unexpectedly, the post-hurricane diet contained more mature leaves than new leaves despite the availability of new leaves. Leaves contained higher amounts of minerals than reproductive parts and with the exception of Cecropia peltata stems, plant parts were low in sodium. Cecropia peltata is a pioneer species that grows following habitat disturbance thus the ingestion of these stems may be a potential mechanism to avoid sodium deficiency in this damaged forest. Calcium and zinc were found above recommended values in most food items; however, both positively predicted food selection, which may reflect a difference between their abundance and their bioavailability. However, as mature leaves contained more calcium than other plant parts, their high post-hurricane consumption may also be a response to the absence of figs and the need to find an alternate calcium source. This study highlights how habitat disturbance may affect mineral abundance and the dietary choices of primates.

Genetic Structure and Kinship Patterns in a Population of Black Howler Monkeys,Alouatta pigra, atPalenqueNationalPark,Mexico

We investigated the genetic structure and kinship patterns of black howler monkeys (Alouatta pigra) at Palenque National Park, Mexico. Fecal samples from 49 individuals residing in eight social groups were successfully genotyped for 19 polymorphic microsatellite markers known to be variable in other ateline primates. Overall, genetic diversity was low (H(o) = 0.588) with an average of 4.2 alleles per loci (range = 2-8). We found that intergroup genetic variation among adults was relatively high (mean between-group F(ST) = 0.119), largely due to the genetic divergence of one study group from the others. Intragroup kinship patterns showed that in most social groups, either adult males, adult females, or individuals of both sexes resided with same-sexed adult kin, suggesting that some black howler males and females may not disperse from their natal group or may disperse with related individuals. Of the six sampled immigrant males, two males joined established groups by themselves, and four males formed two pairs that each took over the social group they joined after evicting the resident males. Males in both these coalitions were genetically closely related, while the two solitary immigrants were not closely related to any of the resident males present in the group they joined.

Parasites, Primates, and Ant-Plants: Clues to the Life Cycle of Controrchis spp. in Black Howler Monkeys (Alouatta pigra) in Southern Belize

The purpose of this study was to investigate the prevalence, intensity, and possible transmission routes of the trematode, Controrchis spp. (Dicrocoeliidae), in a population of black howler monkeys (Alouatta pigra) near Monkey River, Belize. Alouatta pigra are arboreal primates that are typically folivorous and frugivorous. Controrchis is a dicrocoeliid trematode and, as such, should require a gastropod and an ant (Formicidae) intermediate host for transmission. From January to July 2005 and February 2006 to June 2007, we collected fecal samples and focal animal data from 18 individual primates in four social groups. Feces were stored in either 10% buffered formalin or 95% ethanol and examined using a double-centrifugation sugar-flotation technique. The prevalence of Controrchis spp. was 89%, and the mean intensity was 2.29 eggs per gram (epg), with a range of 1.00-6.57 epg. A general linear mixed model to examine the effect of sex, rainfall, and time spent feeding on various plant species, while controlling for individual and group identity, revealed that both group and the amount of time spent feeding on trumpet trees (Cecropia peltata) by individuals predicted the prevalence and intensity of Controrchis spp. infestation. Cecropia peltata has a mutualistic relationship with Azteca spp. ants and constitutes an important food source for A. pigra. Our findings provide strong, circumstantial evidence that A. pigra are infected with Controrchis spp. through the ingestion of metacercariae in Azteca spp. when feeding on C. peltata. Because C. peltata is a pioneer tree species and typically occurs in disturbed forests, results from this study suggest an important link between habitat disturbance and parasitism in a wild mammal.

Density, Distribution, and Home Range of the Black Howler Monkey (Alouatta pigra) at Lamanai, Belize

The population of black howler monkeys (Alouatta pigra) at the Lamanai Archaeological Reserve in northwestern Belize was studied for a total of 11.5 months during 2 wet and 2 dry seasons between October 1993 and May 1995. We estimated home-range size and range overlap of troops in order to examine territoriality, and tested the null hypothesis that the population is uniformly distributed throughout the reserve in order to examine habitat use. Home-range sizes were similar to those at Bermudian Landing, Belize, but smaller than those at Tikal, Guatemala. Mean home-range size was estimated as 15.3 ha with 52% overlap based on a 1.0-ha grid. There was no evidence for territoriality. Population distribution was generally uniform, but ruin sites appeared to be preferred habitat and edge habitat was least frequented.

Predictors of male residence patterns in groups of black howler monkeys

AbstractMales may share access to fertilizable females (polygynandry) in one environment while, under other conditions, polygynous (one‐male or ‘harem’) mating is the norm. However, few studies in mammals have empirically investigated the factors predicting when males will coexist in bisexual reproductive units rather than live in one‐male associations with females. We examined patterns of male group membership in a population of black howler monkeys Alouatta pigra residing in two habitats (deciduous and riparian) of a tropical moist forest environment in Belize, Central America. Using general linear and logistic regression modeling, we evaluated nine variables as possible predictors of male residence patterns (one‐male groups or multimale groups). Our results suggest that adult sex ratio and group size are the best predictors of male residence patterns in both habitats. Our findings provide empirical support for theoretical expectations that male reproductive strategies will be a function of habitat‐related demographic patterns and the subsequently varying potential of males to monopolize females in heterogeneous regimes. This study may have important implications for our understanding of features of mammalian societies in which males compete directly for access to females.

Population of the black howler monkey (Alouatta pigra) in a fragmented landscape in Palenque, Chiapas, Mexico.

Little is known about the population characteristics of Alouatta pigra under conditions of forest fragmentation-information that is important to understanding its tolerance to habitat loss. In this work we present data on forest loss and on troop size, age, and sex composition for a population of black howler monkeys existing in the fragmented landscape surrounding the Mayan site of Palenque, Chiapas, Mexico. Two aerial photos (1:70,000) of the study area (261 km(2)) taken in 1984 and 2001 were examined to assess forest loss. Between June and December 2001 and January and March 2002 we surveyed 44 forest fragments for the presence of howler monkeys. Examination of aerial photos showed that 33% of the forest present in 1984 had disappeared by 2001, and detected an increment in the number of forest fragments present in the landscape. We discovered a total of 115 howler monkeys living in 22 of the 44 forest fragments studied, of which 107 were members of 18 troops. The rest were solitary males or small groups of males living in isolated forest fragments. Troop size ranged from two to 15 individuals (mean 5.9+3.0 ind). 31% and 15% of individuals in the troops were juveniles and infants, respectively, suggesting continued reproductive activity. Howler monkey troops in the forest fragments were on average smaller (5.9+/-3.0 ind) than troops in the nearby protected forest of the Mayan site (7.0+/-2.8 ind). The mean density of howlers in the forest fragments was 119+/-82.9 ind/km(2). The establishment of corridors is suggested as a possible conservation scenario for the fragmented howler population investigated, and as a conservation measure to connect this population with the howler population found in the protected forest of the Mayan site.

Survey of the black howler monkey, alouatta pigra, population at the Mayan site of Palenque, Chiapas, Mexico.

A survey of the population of the black howler monkey (Alouatta pigra) present at the Mayan site of Palenque was conducted during 2000. A total of 911 man/hours, spread over 112 days were spent surveying the 600 ha area of pristine forest at the site for howler troops. We detected the presence of 136 individuals of which 131 were members of 20 troops, the rest were 3 solitary adult males and 2 adult males travelling as a pair. Ecological density was estimated at 23 individuals/km(2). Mean troop size was 7.0 individuals and it ranged from 2 - 12 individuals; 60% of the troops were multimale. All sighting of howler monkeys were in evergreen rain forest and 75% were in trees > or = 20 m in height. The reported densities and mean troop size are higher than those reported for the species in Guatemala and in central Quintana Roo, Mexico. The vegetation of the forest contains tree species reported to be used by species of Alouatta in the Moraceae, Sapotaceae, Leguminosae, and Lauraceae plant families. Protection of a large perimeter area (ca 1700 ha) around the archeological site by the Mexican government ensures the conservation of the forest and of the black howler monkey population present at the site.

DIURNAL VOCAL PATTERNS OF THE BLACK HOWLER MONKEY (ALOUATTA PIGRA) AT LAMANAI, BELIZE

Abstract The majority of the literature describing howling monkeys (Cebidae) has focused on only 2 of 6 species in the genus. These studies have revealed differences in behavior between species and differences within species at different locations. One study has been published describing the vocal patterns of the black howler monkey (Alouatta pigra). This species appears to differ markedly from previously described Alouatta. In an effort to further distinguish A. pigra from its congeners, we observed the vocal patterns of an additional population of black howler monkeys. This population exhibited a bimodal calling pattern similar to that previously described for A. pigra, but absent in all but one (A. fusca) of the other species in the genus. The bimodal pattern was evident in both the rainy and dry seasons, with peaks in the morning and afternoon. Midday and afternoon calling were significantly reduced in the dry season. We also made a detailed comparison between both populations to examine the function ...