Differences in diet and activity pattern between two groups of Alouatta palliata associated with the availability of big trees and fruit of top food taxa

Feeding adaptation of François' langurs (Trachypithecus francoisi) to the fragmented limestone habitats in Southwest China

Limestone forests are an unusual habitat for primates, especially fragmented limestone habitats. However, while some research has been conducted on François' langurs (Trachypithecus francois) in these habitats, there is still a need to improve the understanding of their behavioral adaptations to the fragmented limestone habitat. We collected data on the diet of François' langurs in a fragmented limestone habitat in Encheng National Nature Reserve, southwestern Guangxi, China using instantaneous scanning sampling, and their feeding adaptations to the fragmented forest were examined. The results indicated that a total of 101 species of plants were consumed by the langurs. They also fed on two non-plant components, including cliff minerals and at least one species of insect. The langurs ate a higher number of food species in Encheng when compared with the other geographic populations, and they maintained a high level of food diversity and ate more vines. Moreover, they were highly selective in their use of vegetation in their home range, and fewer plants provided a high-quality food source. During the season when food resources were scarce, the consumption of fruits and young leaves decreased as their availability decreased. This led to the use of other food components, such as mature leaves and seeds. The findings support that François' langurs adjust their feeding behavior to cope with seasonal and micro-variations in their dietary requirements and to adapt to their particular environment.

One step forward, two steps backward: The frailty of howler monkey conservation in Los Tuxtlas, Mexico

Most primate taxa are threatened by extinction and their populations are decreasing. The persistence of primates is thus conditional on conservation actions aimed at protecting them and their habitat. Here, we focus on the conservation of mantled howler monkeys (Alouatta palliata) in the Los Tuxtlas Biosphere Reserve, Mexico. Following the creation of the reserve in 1998, habitat availability and howler monkey abundance increased, suggesting that progress was being made in terms of the conservation of this species. Recent events, however, suggest otherwise, as mantled howler monkey habitat within the biosphere reserve is being disturbed by mining operations endorsed by the Mexican government. We report this case to raise awareness about the challenges for primate and habitat conservation in protected areas.

Behavioral responses to riparian and anthropogenic edge effects in mantled howler monkeys (Alouatta palliata) in a disturbed riverine forest

Fragmented forests contain natural edges, including riparian zones, and anthropogenic edges. Edges generally have lower plant density and fewer large trees than forest interior. Riparian edges, however, contain gap-specialist trees yielding leaves with high protein content, providing primates with important resources. We examined mantled howler monkeys' behavioral responses to riparian and anthropogenic edges at La Suerte Biological Research Station (LSBRS), Costa Rica. We predicted the monkeys would spend more time resting and feeding and less time traveling, and be less spatially cohesive, in both anthropogenic and riparian edges compared to forest interior due to lower resource abundance in edges, and in anthropogenic compared to riparian edge due to higher leaf quality in riparian zones. From 2017 to 2020, we collected data across forest zones on activity and spatial cohesion patterns via focal sampling, recording data every 2 min. Howler monkeys were significantly more likely to rest and significantly less likely to travel in both anthropogenic and riparian edges compared to forest interior; however, there were no differences between these edge types. There were significantly more monkeys within a 5-m radius of focal subjects in both anthropogenic and riparian edges compared to forest interior, but no differences between these edge types. While prior research found no differences across zones when only anthropogenic edge and forest interior were compared, results of this study demonstrate that howler monkeys at LSBRS modify their activity patterns in anthropogenic and riparian edge zones compared to forest interior, highlighting the importance of focusing on both natural and anthropogenic edge zones to fully understand primates' behavioral responses in fragmented landscapes.

River edge feeding: Howler monkey feeding ecology in a fragmented riparian forest

Rivers are important components of animal habitats worldwide. The area near riparian edge (⩽100 m from the river) has different abiotic characteristics and vegetation than both forest interior and areas bordering human development, which may lead to differences in animal feeding behaviour. To better contextualize the impact of human-caused habitat destruction on animal feeding ecology, it is important to study both natural riparian and anthropogenic forest edges within the same habitat. We compared howler monkey (Alouatta palliata) feeding behaviour and tree use across four forest zones (riparian edge, anthropogenic edge, forest interior, and combined riparian and anthropogenic edge) in a fragmented riparian rainforest in Costa Rica, La Suerte Biological Research Station (LSBRS). We predicted that monkey feeding behaviour and tree use would differ across forest zones, and especially between riparian and anthropogenic edges due to higher vegetation quality near the river. We observed individual focal monkeys for 30-minute periods, collecting data on monkey feeding behaviour and tree use every 2 minutes. We recorded plant parts eaten and feeding tree taxonomy, and measured feeding trees. Monkeys ate more leaves in riparian edge than in other forest zones, and fed from fewer tree families in riparian edge and forest interior compared to anthropogenic edge. Monkeys also fed from trees with smaller DBH in riparian edge compared to other forest zones, but trees of similar height to forest interior and taller than anthropogenic edge. Our results indicate that riparian zones are rich habitats for howler monkeys and conservation efforts should prioritize their preservation.

All-You-Can-Eat: Influence of Proximity to Maize Gardens on the Wild Diet and the Forest Activities of the Sebitoli Chimpanzee Community in Kibale National Park

Simple Summary

Understanding the resilience of primate populations to the threat of agricultural expansion is critical for effective conservation. Based on individual monitoring from morning to evening of wild chimpanzees in and around a protected area, we showed that the availability of maize at the forest edge had little effect on their activity budget by less resting and no impact on their wild diet and energy expenditure. In this area, large, caloric wild fruits are available year-round, and we observed no behavioral or dietary changes regarding wild resource availability either. Thus, the chimpanzees consume maize opportunistically as a bonus treat in their diet, and the presence of this nutritious resource does not seem to affect their role in seed dispersal and forest regeneration.

Abstract

Frugivorous primates have developed several strategies to deal with wild fruit scarcity, such as modifying their activity budget or enlarging their diet. Agricultural expansion threatens primate habitats and populations (e.g., disease transmission, agrochemical exposure), but it also increases crop feeding opportunities. We aimed at understanding whether maize presence close to the natural habitat of chimpanzees, a threatened species, would lead to significant behavioral modifications. We monitored 20 chimpanzees over 37 months in Kibale National Park, Uganda, with maize gardens at the forest edge. Based on focal nest-to-nest data, we analyzed their diet, activity budget, and energy balance depending on wild fruit and maize availability. We found that the Sebitoli area is a highly nutritive habitat for chimpanzees, with large and caloric wild fruits available all year long. The chimpanzees opportunistically consume maize and exploit it by resting less during maize season. However, no significant variation was found in daily paths and energy expenditures according to maize availability. No behavioral or energy modification was observed regarding wild resources either. Despite the availability of nutritious domestic resources, chimpanzees still exploit wild fruits and do not limit their movements. Thus, their contribution to seed dispersal and forest regeneration in this area is not affected.

Forest maturity has a stronger influence on the prevalence of spider monkeys than howler monkeys in an anthropogenically impacted rainforest landscape

The transformation and depletion of primary forest over the past few decades have placed almost half of the world’s primate species under the threat of extinction. Developing any successful conservation program for primates requires distribution and demography data, as well as an understanding of the relationships between these factors and their habitat. Between March and June 2010 and 2011 we collected data on the presence and demographic parameters of howler and spider monkeys by carrying out surveys, and validated our findings using local knowledge. We then examined the relationship between forest type and the presence of these primates at 54 sites in the northern area of the Selva Zoque Corridor, Mexico. We detected 86 spider monkey groups across 31 plots and censused 391 individuals (mean ± SD = 5.9 ± 3.0 individuals per sub-group, n = 67 sub-groups). We also detected 69 howler monkey groups across 30 plots and censused 117 individuals (mean ± SD = 5.3 ± 2.4 individuals per group, n = 22 groups). Howler monkey presence was not related to any specific vegetation type, while spider monkeys were present in areas with a higher percentage of tall forest (trees > 25 m high). Overall, spider monkeys were more prevalent than howler monkeys in our sampling sites and showed demographic characteristics similar to those in better protected areas, suggesting that the landscape features in the Uxpanapa Valley are suitable for their needs. Conversely, howler monkey presence was found to be more limited than in other regions, possibly due to the extended presence of spider monkeys.

Anthropogenic edges impact howler monkey (Alouatta palliata) feeding behaviour in a Costa Rican rainforest

Anthropogenic forest fragmentation impacts many aspects of animal behaviour, including feeding ecology. With forests increasingly fragmented in tropical regions due to human development, the proportion of forest edge (≤ 100 m from clear-cut regions) is higher relative to forest interior. Forest edges differ in vegetation from interior, making it important to better understand how anthropogenic edges impact the feeding behaviour of primates such as mantled howler monkeys (Alouatta palliata). We predicted that howler monkeys would feed on higher-quality plant resources, from a larger number of tree families, and from larger trees in forest interior compared to anthropogenic forest edge. We surveyed howler monkey feeding behaviour across forest zones in a fragmented rainforest in Costa Rica, La Suerte Biological Research Station. We observed individual monkeys for 30-minute periods, collecting data on their feeding behaviour and tree use at 2-minute intervals. We measured feeding trees and recorded the plant parts and taxonomy of resources consumed. Monkeys consumed more leaves and fewer stems and fed from a smaller number of tree families in the forest interior, while they consumed fewer leaves and more stems and fed from a larger number of tree families in the forest edge. Monkeys also fed from larger, taller trees in the forest interior than the edge. The differences in howler monkey feeding behaviour between forest zones attest to the impact of human disturbance on howler monkey feeding ecology.

Lone males: Solitary and group-living male howler monkey (Alouatta palliata) behavioral ecology in a Costa Rican rainforest

OBJECTIVES

Many group-living primate species have evolved the capacity for some individuals to live alone for part of their lives, but this solitary life stage has rarely been the subject of focused research. The mantled howler monkey (Alouatta palliata) is a social primate species with bisexual dispersal that lives in mixed-sex groups with low male-to-female sex ratios. Consequently, males often spend a long period of their lives as solitary individuals. This study compares the tree use, feeding, and long-distance vocalization behavior of solitary and group-living mantled howler monkey males living within a fragmented rainforest in Costa Rica, La Suerte Biological Research Station. Based on differences in competitive ability between solitary and group-living males, we predicted that lone males would be found in significantly smaller feeding and resting trees, consume more low-quality foods, and produce shorter howling bouts made at lower rates than group-living males.

MATERIALS AND METHODS

We collected data on tree use and feeding during 30-min focal samples on male focal animals, recording data at 2-min intervals. We measured the trees in which the monkeys fed and rested for two or more intervals, and recorded the plant parts consumed. We recorded howling behavior using all-occurrences sampling.

RESULTS

Lone males used significantly smaller feeding and resting trees, consumed more low-quality foods, and howled at lower rates but had longer howling bouts triggered by anthropogenic noise more than group-living males.

DISCUSSION

Our results demonstrate that lone males differ in their behavioral ecology compared to group-living males, thus improving understanding of the solitary male life stage in primates.

Habitat suitability for primate conservation in north-east Brazil

Brazil has a high diversity of primates, but increasing anthropogenic pressures and climate change could influence forest cover in the country and cause future changes in the distribution of primate populations. Here we aim to assess the long-term suitability of habitats for the conservation of three threatened Brazilian primates (Alouatta belzebul, Sapajus flavius and Sapajus libidinosus) through (1) estimating their current and future distributions using species distribution models, (2) evaluating how much of the areas projected to be suitable is represented within protected areas and priority areas for biodiversity conservation, and (3) assessing the extent of remaining forest cover in areas predicted to be suitable for these species. We found that 88% of the suitable areas are outside protected areas and only 24% are located in areas with forest cover. Although not within protected areas, 27% of the climatically suitable areas are considered priority areas for conservation. Future projections, considering a severe climate change scenario, indicate that A. belzebul, S. flavius and S. libidinosus may lose up to 94, 98 and 54% of their suitable range, respectively. The establishment of primate populations and their long-term survival in these areas are at risk. Mitigation actions such as the implementation of new protected areas, forest restoration and reduction of greenhouse gas emissions will be essential for the conservation of Brazilian primates.

Life in a fragment: Evolution of foraging strategies of translocated collared brown lemurs, Eulemur collaris, over an 18-year period

While the drivers of primate persistence in forest fragments have been often considered at the population level, the strategies to persist in these habitats have been little investigated at the individual or group level. Considering the rapid variation of fragment characteristics over time, longitudinal data on primates living in fragmented habitats are necessary to understand the key elements for their persistence. Since translocated animals have to cope with unfamiliar areas and face unknown fluctuations in food abundance, they offer the opportunity to study the factors contributing to successful migration between fragments. Here, we illustrated the evolution of the foraging strategies of translocated collared brown lemurs (Eulemur collaris) over an 18-year period in the Mandena Conservation Zone, south-east Madagascar. Our aim was to explore the ability of these frugivorous lemurs to adjust to recently colonized fragmented forests. Although the lemurs remained mainly frugivorous throughout the study period, over the years we identified a reduction in the consumption of leaves and exotic/pioneer plant species. These adjustments were expected in frugivorous primates living in a degraded area, but we hypothesize that they may also reflect the initial need to cope with an unfamiliar environment after the translocation. Since fragmentation is often associated with the loss of large trees and native vegetation, we suggest that the availability of exotic and/or pioneer plant species can provide an easy-to-access, nonseasonal food resource and be a key factor for persistence during the initial stage of the recolonization.

Dietary flexibility of Bale monkeys (Chlorocebus djamdjamensis) in southern Ethiopia: effects of habitat degradation and life in fragments

BACKGROUND

Understanding the effects of habitat modification on the feeding strategies of threatened species is essential to designing effective conservation management plans. Bale monkeys (Chlorocebus djamdjamensis) are endemic to the rapidly shrinking montane forests of the southern Ethiopian Highlands. Most populations inhabit continuous bamboo forest subsisting largely on the young leaves and shoots of a single species of bamboo. Because of habitat disturbance in recent decades, however, there are now also several dozen small populations inhabiting isolated forest fragments where bamboo has been degraded. During 12-months, we assessed Bale monkey responses to habitat degradation by comparing habitat composition, phenological patterns, and feeding ecology in a largely undisturbed continuous forest (Continuous groups A and B) and in two fragments (Patchy and Hilltop groups).

RESULTS

We found that habitat quality and food availability were much lower in fragments than in continuous forest. In response to the relative scarcity of bamboo in fragments, Bale monkeys spent significantly less time feeding on the young leaves and shoots of bamboo and significantly more time feeding on non-bamboo young leaves, fruits, seeds, stems, petioles, and insects in fragments than in continuous forest. Groups in fragments also broadened their diets to incorporate many more plant species (Patchy: ≥ 47 and Hilltop: ≥ 35 species)-including several forbs, graminoids and cultivated crops-than groups in continuous forest (Continuous A: 12 and Continuous B: 8 species). Nevertheless, bamboo was still the top food species for Patchy group (30% of diet) as well as for both continuous forest groups (mean = 81%). However, in Hilltop group, for which bamboo was especially scarce, Bothriochloa radicans (Poaceae), a grass, was the top dietary species (15% of diet) and bamboo ranked 10th (2%).

CONCLUSIONS

We demonstrate that Bale monkeys are more dietarily flexible than previously thought and able to cope with some degradation of their primary bamboo forest habitat. However, crop raiding and other terrestrial foraging habits more common among fragment groups may place them at greater risk of hunting by humans. Thus, longitudinal monitoring is necessary to evaluate the long-term viability of Bale monkey populations in fragmented habitats.

Association of Anthropogenic Disturbances and Intestinal Parasitism in Ecuadorian Mantled Howler Monkeys, Alouatta palliata aequatorialis

Forest disturbance and human encroachment have the potential to influence intestinal parasite communities in animal hosts by modifying nutritional health, physiological stress, host densities, contact rates, and ranging patterns. Anthropogenic disturbances also have the ability to affect the ecological landscape of parasitic disease, potentially impacting the health of both wildlife and people. Our research investigated the association of forest disturbance and human encroachment on intestinal parasite communities in mantled howler monkeys, Alouatta palliata aequatorialis. We found that individual parasite species prevalence was associated with group size and forest disturbance. Proximity to people was not a direct factor influencing intestinal parasitism; rather, several human proximity indices were related to group size, which was in turn related to overall species richness and the presence of specific parasite species. These results, coupled with previous findings, suggest that anthropogenic disturbances are likely influencing intestinal parasite communities. Though no single study has definitively explained all relationships between anthropogenic disturbances and intestinal parasitism, we propose that our models are appropriate for meta-analysis testing across other species and environments.

Small-scale variability in a mosaic tropical rainforest influences habitat use of long-tailed macaques

Pristine habitats have generally been considered to be the most important ecological resource for wildlife conservation, but due to forest degradation caused by human activities, mosaics of secondary forests have become increasingly prominent. We studied three forest types in a mosaic tropical forest consisting of short secondary forest (SS), tall secondary forest (TS) and freshwater swamp forest (SF). These forests differed in stand structure and floristic composition, as well as phenological productivity of fruits, flowers and young leaves. We examined habitat use of long-tailed macaques (Macaca fascicularis) in relation to indices of phenological activity. The macaques used the SS for feeding/foraging more than the TS and the SF. This was because the SS had higher productivity of fruit, which is a preferred food resource for macaques. Stem densities of young leaves in the SS and the TS also influenced habitat use, as they provided more clumped resources. Use of SF was limited, but these forests provided more species-rich resources. Our results showed that M. fascicularis responded to small-scale variability in phenological activity between forest types found in a heterogeneous mosaic forest, with young secondary regrowth forests likely providing the most important food resources. Mosaic landscapes may be important as they can buffer the effects of temporal food resource variability in any given forest type. In our increasingly human-altered landscapes, a better understanding of the role of secondary forest mosaics is crucial to the conservation and management of wildlife habitats and the animals they support.

Hormonal correlates of energetic condition in mantled howler monkeys

Hormones have a key role in energy allocation, so their study allows understanding individual metabolic strategies. Because different hormones convey different information on the responses of individuals to energetic demands, a simultaneous analysis of variation in multiple hormones may offer a more reliable picture of metabolic strategies than single hormone assessments. In this study we focused on determining which factors were related to variation in fecal glucocorticoid and thyroid hormone metabolites in wild mantled howler monkeys (Alouatta palliata). Over 12months, we determined fecal glucocorticoid and thyroid hormone metabolite levels of 11 adults belonging to two groups, and examined the relationship between hormone metabolites and a variety of behavioral, physiological, and ecological factors (e.g., food intake, sex/reproductive state, activity, participation in agonistic interactions). We found that glucocorticoids were elevated in gestating and lactating females compared to males and cycling females, and were also higher when individuals were more active and participated in agonistic interactions. Thyroid hormone levels were also related to sex/reproductive state and activity, but were additionally positively related to fruit intake and negatively related to young leaf intake. Our study demonstrates that the non-invasive measurement of glucocorticoid and thyroid hormones of howler monkeys allows assessing different underlying physiological processes. By combining different biomarkers, which has seldom been done with wildlife, we could also parse the influence of psychological vs. metabolic challenges for individual energetic condition, which may be instrumental for deciding which factors should be accounted for when studying different hormone-behavior interactions.

Howlers and marmosets in Pacatuba: an overcrowded existence in a semi-deciduous Atlantic forest fragment?

The Atlantic forest of Brazil is extremely fragmented. This fragmentation has had a toll on the mammal’s assemblages. Although different species are not equally susceptible to fragmentation, populations of some species have become locally extinct. Primate populations in these fragments are in decline or have gone locally extinct. However, there is a dearth of information on density of primates in the highly fragmented Atlantic forest of NE Brazil. We conducted a series of censuses to record primates and other mammals in the Pacatuba semi deciduous forest (~267 ha). Most of the midsized and large mammals disappeared, even fragment-tolerant species such as sloths and coatis are missing in the area. Currently, marmosets (

Proximal and Distal Predictors of the Spider Monkey's Stress Levels in Fragmented Landscapes

The rapid loss, fragmentation and degradation of tropical forests threaten the survival of many animal species. However, the way in which these phenomena affect animal health has been poorly explored, thus limiting the design of appropriate conservation strategies. To address this, here we identified using linear mixed models the effect of proximal (diet, activity pattern, hunting and logging) and distal (sum of the basal areas of fruiting-tree species [SBAFS], landscape forest cover and degree of forest fragmentation) variables over fecal glucocorticoid metabolite (fGCM) levels-hormones associated with animal health and fitness-of six groups of spider monkeys (Ateles geoffroyi) inhabiting six landscapes with different spatial structures in Mexico. Proximal variables showed a stronger predictive power over fGCMs than distal. In this sense, increases in travel time, the occurrence of hunting, and reductions in rest time and fruit consumption resulted in higher fGCM levels. Regarding distal variables, increases in SBAFS were negatively related to fGCM levels, thus suggesting that food scarcity increases stress hormone levels. Nevertheless, contrary to theoretical expectations, spider monkeys living in smaller tracts of forest spent less time travelling, but the same time feeding on fruit as those in more forested areas. The lower net energy return associated with this combination of factors would explain why, contrary to theoretical expectations, increased forest cover was associated with increased levels of fGCMs in these groups. Our study shows that, at least in the short term, spider monkeys in fragmented landscapes do not always present higher levels of stress hormones compared to those inhabiting continuous forest, and the importance of preserving fruit sources and controlling hunting for reducing the levels of stress hormones in free ranging spider monkeys.

Feeding Strategies of Brown Howler Monkeys in Response to Variations in Food Availability

Primates display varying degrees of behavioral flexibility that allow them to adjust their diet to temporal changes in food availability. This trait might be critical for the survival of folivorous-frugivorous species inhabiting small forest fragments, where the availability of food resources tends to be lower than in large fragments and continuous forests. However, the scarcity of studies addressing this issue hampers our understanding of the adaptive behaviors that favor the survival of these primates in low-quality habitats. We conducted a 36-mo study testing the hypothesis that brown howler monkeys (Alouatta guariba clamitans) are able to adjust their diet in response to local and seasonal changes in resource availability. We compared the diet of six free-ranging groups inhabiting three small (<10 ha) and three large (>90 ha) Atlantic forest fragments in southern Brazil and estimated the temporal availability of their top food species (i.e., those species that together contribute ≥80% of total feeding records). We found that brown howlers exploited similarly rich diets in small (45, 54, and 57 plant species) and large (48, 51, and 56 species) fragments. However, intermonth diet similarity was higher for groups in small fragments, where howlers also fed on plant items from nine alien species. Fruits and leaves were the most consumed plant items in both small (42% and 49% of feeding records, respectively) and large (51% and 41%, respectively) fragments. The consumption of young leaves was higher in small than in large fragments, whereas the consumption of other plant items did not show a pattern related to fragment size. Regarding the contribution of growth forms as food sources, only the exploitation of palms showed a pattern related to fragment size. Palms contributed more to the diet of groups inhabiting large fragments. The availability of seasonal food items–ripe fruits and young leaves–influenced their consumption in both habitat types. Therefore, brown howlers cope with local and seasonal fluctuations in food availability by opportunistically exploiting resources. We believe that this feeding flexibility is a key component of the phenotypic plasticity that enables howlers to thrive in disturbed habitat patches, where periods of scarcity of preferred foods shall be more common.

Intragroup genetic relatedness in two howler monkey species (Alouatta pigra and A. palliata): Implications for understanding social systems and dispersal

The degree of genetic relatedness among group members is influenced by dispersal, group formation and composition, mating systems, and other socioecological factors. Making inferences about differences between species in their socio-genetic structure is difficult because studies rarely compare multiple species. In this study, we use multilocus microsatellite genotype data to analyze intragroup genetic relatedness in two howler monkey species (Alouatta palliata and A. pigra). We test the prediction that their patterns of intragroup genetic relatedness will be distinct based on expectations derived from their distinct social systems. Alouatta palliata is expected to have low levels of intragroup relatedness, given that both males and females are reported to disperse from their natal groups, and to join groups with no close kin. Levels of relatedness among A. pigra group members are expected to be variable according to the history of group formation, with new groups formed by unrelated individuals and well-established groups having close kin due to female nepotism and sometimes by takeovers by coalitions of related males. Our results indicate that in both species, most groups contain closely related same-sex and/or inter-sex dyads. This suggests that philopatry in A. palliata may be more common than reported or that individuals are using alternative strategies to reside with close kin. We found greater variation among groups in female-female relatedness in A. palliata than in A. pigra, implying that these species have distinct socio-genetic structures. Further studies including both long-term observational and genetic data are necessary to understand the mechanisms that determine the degree of variation in intragroup genetic relatedness within and among populations for both species. Ecological and demographic data are also necessary to determine the importance of other factors, especially habitat loss and fragmentation, in determining the degree of relatedness in howler monkey groups.

Effects of Local Habitat Variation on the Behavioral Ecology of Two Sympatric Groups of Brown Howler Monkey (Alouatta clamitans)

Although the brown howler monkey (Alouatta clamitans) is a relatively well-studied Neotropical primate, its behavioral and dietary flexibility at the intra-population level remains poorly documented. This study presents data collected on the behavior and ecology of two closely located groups of brown howlers during the same period at the RPPN Feliciano Miguel Abdala in southeastern Brazil. One group occupied a primary valley habitat, henceforth the Valley Group (VG), and the other group occupied a regenerating hillside habitat, the Hill Group (HG). We hypothesized differences in the behavior and ecological parameters between these sympatric groups due to the predicted harsher conditions on the hillside, compared to the valley. We measured several habitat parameters within the home range of both groups and collected data on the activity budget, diet and day range lengths, from August to November 2005, between dawn and dusk. In total, behavioral data were collected for 26 (318 h) and 28 (308 h) sampling days for VG and HG, respectively. As we predicted, HG spent significantly more time feeding and consumed less fruit and more leaves than VG, consistent with our finding that the hillside habitat was of lower quality. However, HG also spent less time resting and more time travelling than VG, suggesting that the monkeys had to expend more time and energy to obtain high-energy foods, such as fruits and flowers that were more widely spaced in their hill habitat. Our results revealed that different locations in this forest vary in quality and raise the question of how different groups secure their home ranges. Fine-grained comparisons such as this are important to prioritize conservation and management areas within a reserve.

Contagious deposition of seeds in spider monkeys' sleeping trees limits effective seed dispersal in fragmented landscapes

The repeated use of sleeping sites by frugivorous vertebrates promotes the deposition and aggregation of copious amounts of seeds in these sites. This spatially contagious pattern of seed deposition has key implications for seed dispersal, particularly because such patterns can persist through recruitment. Assessing the seed rain patterns in sleeping sites thus represents a fundamental step in understanding the spatial structure and regeneration of plant assemblages. We evaluated the seed rain produced by spider monkeys (Ateles geoffroyi) in latrines located beneath 60 sleeping trees in two continuous forest sites (CFS) and three forest fragments (FF) in the Lacandona rainforest, Mexico. We tested for differences among latrines, among sites, and between forest conditions in the abundance, diversity (α-, β- and, γ-components) and evenness of seed assemblages. We recorded 45,919 seeds ≥ 5 mm (in length) from 68 species. The abundance of seeds was 1.7 times higher in FF than in CFS, particularly because of the dominance of a few plant species. As a consequence, community evenness tended to be lower within FF. β-diversity of common and dominant species was two times greater among FF than between CFS. Although mean α-diversity per latrine did not differ among sites, the greater β-diversity among latrines in CFS increased γ-diversity in these sites, particularly when considering common and dominant species. Our results support the hypothesis that fruit scarcity in FF can 'force' spider monkeys to deplete the available fruit patches more intensively than in CFS. This feeding strategy can limit the effectiveness of spider monkeys as seed dispersers in FF, because (i) it can limit the number of seed dispersers visiting such fruit patches; (ii) it increases seed dispersal limitation; and (iii) it can contribute to the floristic homogenization (i.e., reduced β-diversity among latrines) in fragmented landscapes.

Dietary variability in the western black crested gibbon (Nomascus concolor) inhabiting an isolated and disturbed forest fragment in Southern Yunnan, China

Forest fragmentation and isolation can reduce the size of available habitat and lead to lower food availability for some primate species. The persistence of nonhuman primates in fragments depends largely on their ability to adjust their diet in response environmental change. The western black crested gibbon (Nomascus concolor) is distributed in northern Vietnam, northwestern Laos, and southwestern China, but little is known about its diet except from studies in the well-protected forests of Mt. Wuliang and Mt. Ailao, central Yunnan. We studied food abundance and diet over 2 years in a small group surviving in an isolated and disturbed forest at Bajiaohe, southern Yunnan, and drew a comparison with the population at Dazhaizi in Mt. Wuliang. We found that gibbons at Bajiaohe consumed mostly fruit, but did not eat figs, unlike most other gibbon populations. Liana fruits and mature leaves were used as alternative foods during periods of tree fruit scarcity. Our results indicate that gibbons in Bajiaohe respond to habitat fragmentation and isolation by consuming a variety of plant species, depending on those that are locally available, and increasing time spent feeding on fruits of trees and lianas rather than increasing time spent consuming leaves.

Influence of climatic variables, forest type, and condition on activity patterns of Geoffroyi's spider monkeys throughout Mesoamerica

Understanding how species cope with variations in climatic conditions, forest types and habitat amount is a fundamental challenge for ecologists and conservation biologists. We used data from 18 communities of Mesoamerican spider monkeys (Ateles geoffroyi) throughout their range to determine whether their activity patterns are affected by climatic variables (temperature and rainfall), forest types (seasonal and nonseasonal forests), and forest condition (continuous and fragmented). Data were derived from 15 published and unpublished studies carried out in four countries (Mexico, El Salvador, Costa Rica, and Panama), cumulatively representing more than 18 years (221 months, >3,645 hr) of behavioral observations. Overall, A. geoffroyi spent most of their time feeding (38.4 ± 14.0%, mean ± SD) and resting (36.6 ± 12.8%) and less time traveling (19.8 ± 11.3%). Resting and feeding were mainly affected by rainfall: resting time increased with decreasing rainfall, whereas feeding time increased with rainfall. Traveling time was negatively related to both rainfall and maximum temperature. In addition, both resting and traveling time were higher in seasonal forests (tropical dry forest and tropical moist forest) than in nonseasonal forests (tropical wet forest), but feeding time followed the opposite pattern. Furthermore, spider monkeys spent more time feeding and less time resting (i.e., higher feeding effort) in forest fragments than in continuous forest. These findings suggest that global climate changes and habitat deforestation and fragmentation in Mesoamerica will threaten the survival of spider monkeys and reduce the distributional range of the species in the coming decades.

Better few than hungry: flexible feeding ecology of collared lemurs Eulemur collaris in littoral forest fragments

BACKGROUND

Frugivorous primates are known to encounter many problems to cope with habitat degradation, due to the fluctuating spatial and temporal distribution of their food resources. Since lemur communities evolved strategies to deal with periods of food scarcity, these primates are expected to be naturally adapted to fluctuating ecological conditions and to tolerate a certain degree of habitat changes. However, behavioral and ecological strategies adopted by frugivorous lemurs to survive in secondary habitats have been little investigated. Here, we compared the behavioral ecology of collared lemurs (Eulemur collaris) in a degraded fragment of littoral forest of south-east Madagascar, Mandena, with that of their conspecifics in a more intact habitat, Sainte Luce.

METHODOLOGY/PRINCIPAL FINDINGS

Lemur groups in Mandena and in Sainte Luce were censused in 2004/2007 and in 2000, respectively. Data were collected via instantaneous sampling on five lemur groups totaling 1,698 observation hours. The Shannon index was used to determine dietary diversity and nutritional analyses were conducted to assess food quality. All feeding trees were identified and measured, and ranging areas determined via the minimum convex polygon. In the degraded area lemurs were able to modify several aspects of their feeding strategies by decreasing group size and by increasing feeding time, ranging areas, and number of feeding trees. The above strategies were apparently able to counteract a clear reduction in both food quality and size of feeding trees.

CONCLUSIONS/SIGNIFICANCE

Our findings indicate that collared lemurs in littoral forest fragments modified their behavior to cope with the pressures of fluctuating resource availability. The observed flexibility is likely to be an adaptation to Malagasy rainforests, which are known to undergo periods of fruit scarcity and low productivity. These results should be carefully considered when relocating lemurs or when selecting suitable areas for their conservation.

Effects of habitat fragmentation and disturbance on howler monkeys: a review

We examined the literature on the effects of habitat fragmentation and disturbance on howler monkeys (genus Alouatta) to (1) identify different threats that may affect howlers in fragmented landscapes; (2) review specific predictions developed in fragmentation theory and (3) identify the empirical evidence supporting these predictions. Although howlers are known for their ability to persist in both conserved and disturbed conditions, we found evidence that they are negatively affected by high levels of habitat loss, fragmentation and degradation. Patch size appears to be the main factor constraining populations in fragmented habitats, probably because patch size is positively related to food availability, and negatively related to anthropogenic pressures, physiological stress and parasite loads. Patch isolation is not a strong predictor of either patch occupancy or population size in howlers, a result that may be related to the ability of howlers to move among forest patches. Thus, we propose that it is probable that habitat loss has larger consistent negative effects on howler populations than habitat fragmentation per se. In general, food availability decreases with patch size, not only due to habitat loss, but also because the density of big trees, plant species richness and howlers' home range size are lower in smaller patches, where howlers' population densities are commonly higher. However, it is unclear which vegetation attributes have the biggest influence on howler populations. Similarly, our knowledge is still limited concerning the effects of postfragmentation threats (e.g. hunting and logging) on howlers living in forest patches, and how several endogenous threats (e.g. genetic diversity, physiological stress, and parasitism) affect the distribution, population structure and persistence of howlers. More long-term studies with comparable methods are necessary to quantify some of the patterns discussed in this review, and determine through meta-analyses whether there are significant inter-specific differences in species' responses to habitat loss and fragmentation.