Daily Path Length Research Articles

Ecological Correlates of Ranging Behavior in Bearded Sakis (Chiropotes sagulatus) in a Continuous Forest in Guyana

Group size and the distribution and quality of food resources are among the most important determinants of primate ranging behavior. In this study, I use the framework of the ecological constraints model to assess correlates of range size of a free-ranging group of bearded sakis (Chiropotes sagulatus). Bearded sakis are among the widest ranging neotropical primates, yet the lack of data from continuous forest populations has made understanding the factors influencing such large ranges difficult. I collected data on ranging behavior and diet during 44 full-day follows over 15 mo. The focal group used a home range of ca. 1000 ha and had daily path lengths of 2.8–6.5 km (mean = 4.0 km). Daily path length did not significantly correlate with group size, patch quality, food availability, or the spatial distribution of feeding trees. Monthly home range size significantly positively correlated with group size and patch quality. The focal group had significantly shorter paths when ripe fruit consumption was higher and had more diverse diets, visited more food patches, and used larger monthly home ranges when they consumed a higher percentage of seeds. The results of this study, combined with other recent studies of Chiropotes in continuous forest, suggest that large home ranges (approaching 1000 ha) are characteristic of the genus. Although range size may be related to group size and food patch size, I suggest nutrient mixing and the need to balance the effects of seed secondary compounds as additional explanations for the large ranges of bearded sakis.

Habitat Use and Activity Patterns as an Indication of Fragment Quality in a Strepsirrhine Primate

Considerable intraspecific variation exists in responses to habitat fragmentation owing to regional differences in fragment quality. Habitat use and activity patterns of resident populations are related to the abundance and predictability of resources in time and space, and thus space use is one of the most important considerations for evaluating habitat quality. Here I examine inter- and intrasite differences in the ranging behavior; use of the matrix, i.e., surrounding nonhabitat; and activity budgets of ring-tailed lemurs (Lemur catta) inhabiting two forest fragments—Anja Special Reserve and Tsaranoro Valley Sacred Forest—in Madagascar’s central highlands to test the prediction that intraspecific variation in habitat use and activity patterns is indicative of fragment quality. At Anja, Lemur catta has access to abundant year-round anthropogenic resources (introduced fruit trees, agricultural crops, water), whereas the population at Tsaranoro relies on seasonally variable and patchily distributed resources throughout the forest and matrix. Lemur catta at Anja occupy smaller home ranges; have shorter daily path lengths (DPLs); and spend less time foraging and more time resting, locomoting, and engaging in social and territorial behavior. In contrast, groups at Tsaranoro occupy larger home ranges, have longer DPLs, rely heavily on the matrix, and expend most of their energy in foraging behavior. These differences point to variation in the relative habitat quality of the two fragments and are thus an important consideration for conservation managers when assessing the capacity of forest fragments to sustain populations.

Ranging and foraging of Himalayan grey langurs (Semnopithecus ajax) in Machiara National Park, Pakistan

Grey langurs (Semnopithecus spp.) occupy a variety of habitats, ranging from lowland forests and semi-desert to alpine forests. Little is known about their foraging and ranging in alpine forests, which appear to contain less food than lowland forests. We conducted a 1-year study of Himalayan grey langurs (Semnopithecus ajax) in Machiara National Park, Pakistan, where they occur at relatively high altitudes (range 2000-4733m). We followed three groups of different sizes and compositions and examined the effects of ecological and social factors on ranging and feeding. The home-range sizes of a small bisexual group (SBG), a large bisexual group (LBG), and an all-male group (AMG) were 2.35±0.92 (mean±SD; average of four seasons), 3.28±0.55, and 3.52±1.00km(2), respectively, and were largest in winter for all groups. The daily path lengths of the SBG, LBG, and AMG were 1.23±0.28 (mean±SD; average of four seasons), 1.75±0.34, and 1.84±0.70km, respectively; that of the LBG was longer in winter, while that of the AMG was shorter in summer. Both the home-range size and daily path length of the AMG were larger than those of the other groups, even after partialling out the effect of group size differences. The mean altitude used by the langurs and the proportion of animals seen feeding did not differ among seasons or group types. As the mean temperature increased, the altitude used by langurs significantly increased for the SBG and LBG, but not for the AMG. On the other hand, as the temperature increased, the home-range sizes significantly decreased for the SBG and AMG, but not for the LBG. Rainfall did not show any correlation with ranging or feeding in any of the groups. Our results suggested that grey langurs in Machiara National Park employ a high-cost, high-return foraging strategy in winter, and that the ranging of the AMG also reflects its reproductive strategy.

Responses of Javan Gibbon (Hylobates moloch) Groups in Submontane Forest to Monthly Variation in Food Availability: Evidence for Variation on a Fine Spatial Scale

Primates tend to prefer specific plant foods, and primate home ranges may contain only a subset of food species present in an area. Thus, primate feeding strategies should be sensitive to the phenology of specific species encountered within the home range in addition to responding to larger scale phenomena such as seasonal changes in rainfall or temperature. We studied three groups of Javan gibbons (Hylobates moloch) in the Gunung Halimun-Salak National Park, Indonesia from April 2008 to March 2009 and used general linear mixed models (GLMM) and a model selection procedure to investigate the effects of variation in fruit and flower availability on gibbon behavior. Preferred foods were defined as foods that are overselected relative to their abundance, while important food species were those that comprised >5% of feeding time. All important species were also preferred. Season and measurements of flower and fruit availability affected fruit-feeding time, daily path lengths (DPL), and dietary breadth. Models that included the availability of preferred foods as independent variables generally showed better explanatory power than models that used overall fruit or flower availability. For one group, fruit and preferred fruit abundance had the strongest effects on diets and DPL in the models selected, while another group was more responsive to changes in flower availability. Temporal variation in plant part consumption was not correlated in neighboring groups. Our results suggest that fine-scale local factors are important determinants of gibbon foraging strategies.

Factors Influencing the Ranging Behavior of Chacma Baboons (Papio hamadryas ursinus) Living in a Human-Modified Habitat

The introduction and eradication of alien invasive plant species potentially alters feeding and spatial ecology of wild primates. We investigated whether the removal of an important dietary resource for wild chacma baboons (Papio hamadryas ursinus), black wattle (Acacia mearnsii), from a nature reserve would result in longer daily path lengths (DPLs) and greater movement toward other resources, specifically alternative black wattle stands outside the reserve, agricultural plots, and sleeping and geophagy sites. We fitted a juvenile male baboon with a self-releasing GPS collar to track the focal troop’s movements on Wildcliff Nature Reserve and adjacent properties, located in the Western Cape, South Africa, from January 25, 2010 to January 18, 2011. During this time, Working for Water, an environmental conservation initiative of the South African Department of Water Affairs, removed black wattle from the baboons’ home range. We estimated monthly home range (5.30–20.58 km2) and DPL (1.7–11.7 km) and quantified the baboons’ use of five dominant vegetation types. Our vegetation use-availability analysis indicated that the troop preferred black wattle, Afromontane forests, and, to a lesser extent, pasture, but used agricultural plots and fynbos less than expected by availability. With increasing black wattle removal in the core area, the troop traveled further toward distant sources of black wattle, using sleeping sites out of their core area to accommodate such long day journeys. A general linear model indicated that movement to black wattle stands, as well as changing sleeping sites, day length, and both spring and winter seasons all significantly increased DPL. We suggest the influence that alien invasive species and their eradication has on ranging behavior should be a consideration in primate conservation and management policies.

Troop Size and Human‐Modified Habitat Affect the Ranging Patterns of a Chacma Baboon Population in the Cape Peninsula, South Africa

Differences in group size and habitat use are frequently used to explain the extensive variability in ranging patterns found across the primate order. However, with few exceptions, our understanding of primate ranging patterns stems from studies of single groups and both intra- and inter-specific meta-analyses. Studies with many groups and those that incorporate whole populations are rare but important for testing socioecological theory in primates. We quantify the ranging patterns of nine chacma baboon troops in a single population and use Spearman rank correlations and generalized linear mixed models to analyze the effects of troop size and human-modified habitat (a proxy for good quality habitat) on home range size, density (individuals/km(2) ), and daily path length. Intrapopulation variation in home range sizes (1.5-37.7 km(2) ), densities (1.3-12.1 baboons/km(2) ), and daily path lengths (1.80-6.61 km) was so vast that values were comparable to those of baboons inhabiting the climatic extremes of their current distribution. Both troop size and human-modified habitat had an effect on ranging patterns. Larger troops had larger home ranges and longer daily path lengths, while troops that spent more time in human-modified habitat had shorter daily path lengths. We found no effect of human-modified habitat on home range size or density. These results held when we controlled for the effects of both a single large outlier troop living exclusively in human-modified habitat and baboon monitors on our spatial variables. Our findings confirm the ability of baboons, as behaviorally adaptable dietary generalists, to not only survive but also to thrive in human-modified habitats with adjustments to their ranging patterns in accordance with current theory. Our findings also caution that studies focused on only a small sample of groups within a population of adaptable and generalist primate species may underestimate the variability in their respective localities.

Ranging behavior of the François' langur (Trachypithecus francoisi) in limestone habitats of Nonggang, China

Ranging behavior is an important aspect of animal behavior that researchers use to investigate ecological influences on individual behavior. We collected data on the ranging behavior of one group of François' langurs (Trachypithecus francoisi) between August 2003 and July 2004 in a limestone habitat within Nonggang Nature Reserve, China. We evaluated the influences of food availability, water resources and sleeping sites on ranging behavior. During the study period, the total home range size for the study group was 64.5 or (69.3 ha if the lacunae within the borders in which langurs were not observed were included), and the mean daily path length was 541 m. These are well within the range of variation reported in Trachypithecus species. The monthly range size was between 9.8 and 23.3 ha, and monthly range size correlated negatively with young leaf availability. The langurs tended to use a larger range size during young leaf-lean periods. The langurs did not use their home range uniformly, and 74% of their activities occurred within 35% of their home range. The most heavily used quadrats in the home range were located near the most frequently used sleeping sites, suggesting that sleeping sites have a significant influence on the ranging behavior of François' langurs in limestone habitats.

Tamarind tree seed dispersal by ring-tailed lemurs

In Madagascar, the gallery forests of the south are among the most endangered. Tamarind trees (Tamarindus indica) dominate these riverine forests and are a keystone food resource for ring-tailed lemurs (Lemur catta). At Berenty Reserve, the presence of tamarind trees is declining, and there is little recruitment of young trees. Because mature tamarinds inhibit growth under their crowns, seeds must be dispersed away from adult trees if tree recruitment is to occur. Ring-tailed lemurs are likely seed dispersers; however, because they spend much of their feeding, siesta, and sleeping time in tamarinds, they may defecate a majority of the tamarind seeds under tamarind trees. To determine whether they disperse tamarind seeds away from overhanging tamarind tree crowns, we observed two troops for 10 days each, noted the locations of feeding and defecation, and collected seeds from feces and fruit for germination. We also collected additional data on tamarind seedling recruitment under natural conditions, in which seedling germination was abundant after extensive rain, including under the canopy. However, seedling survival to 1 year was lower when growing under mature tamarind tree crowns than when growing away from an overhanging crown. Despite low fruit abundance averaging two fruits/m(3) in tamarind crowns, lemurs fed on tamarind fruit for 32% of their feeding samples. Daily path lengths averaged 1,266 m, and lemurs deposited seeds throughout their ranges. Fifty-eight percent of the 417 recorded lemur defecations were on the ground away from overhanging tamarind tree crowns. Tamarind seeds collected from both fruit and feces germinated. Because lemurs deposited viable seeds on the ground away from overhanging mature tamarind tree crowns, we conclude that ring-tailed lemurs provide tamarind tree seed dispersal services.

Factors Affecting the Ranging Behavior of White-headed Langurs (Trachypithecus leucocephalus)

Ranging behavior is an important aspect of animal behavior that researchers use to investigate ecological influences on individual behavior. We studied the influence of diet, water resources, and sleeping sites on the ranging behavior of 2 groups of white-headed langurs (Trachypithecus leucocephalus) in a limestone habitat at Fusui Nature Reserve, China, between August 2007 and July 2008. During the study period, the total home range sizes for the 2 focal groups were 23.8 ha and 33.8 ha, the mean daily path lengths were 491 m and 512 m, and leaves accounted for 83.4% and 91.0% of the diet, which are well within the range of variation reported for other Trachypithecus. One focal group traveled significantly longer distances in the rainy season months than in the dry season months. This variation may be related to the seasonal difference in food availability and diet. The langurs did not use their home ranges uniformly, and 50% of their activities occurred within 11% (group 1) and 20% (group 2) of their home ranges. The most heavily used quadrats in the home ranges were located near the most frequently used sleeping sites. Moreover, the core areas (>70% of location records) of both groups’ home ranges included ≥1 permanent water pool. The langurs ventured to these pools for drinking when surface water became scarce in the dry season. These results suggest that sleeping sites and water scarcity may be significant influences on the ranging behavior of white-headed langurs in limestone habitat.

Home range, core areas and movement in the ‘critically endangered’ kipunji (Rungwecebus kipunji) in southwest Tanzania

AbstractUnderstanding how threatened forest primates use a heterogeneous landscape is essential to ensuring their survival. Kipunji (Rungwecebus kipunji) are ‘critically endangered’, arboreal monkeys restricted to two sites in Tanzania. Over 90% of the population lives in the degraded Rungwe‐Kitulo forests of the Southern Highlands. In this study, we present the first comprehensive investigation into daily path length and home range size of kipunji, based on data from four groups followed simultaneously over 70 consecutive days on Mt. Rungwe. The mean daily distance travelled was 1293 m (SE 150.82), and daily distance was not significantly correlated to group size. Using fixed kernel density estimation, an area enclosing 90% of the home range calculated using the ‘reference’ method as a smoothing parameter, measured a mean of 306.18 ha (SE 67), and the core area (50% use) was 86.55 ha (SE 18.73). Using the ‘least‐squares cross validation’ method, the mean home range and core area were 205.45 ha (SE 57.02) and 55.45 ha (SE 14.23) respectively. Home range overlap was extensive, although contact between groups was rare, with >97.30% of all observations within 20 min separated by >250 m. The data strongly suggest that kipunji are not territorial.

Diet and ranging behavior of the endangered Javan gibbon (Hylobates moloch) in a submontane tropical rainforest

Altitude influences forest structure and food abundance and distribution, which in turn affect primate feeding and ranging patterns. Javan gibbons (Hylobates moloch) are endemic to forests spanning a broad range of altitudes on Java, Indonesia. Most information about Javan gibbon behavior comes from studies in lowland forests, while the vast majority of wild gibbons remaining inhabit hill and lower montane forests. We studied the diets, activity patterns, and ranging behavior of three gibbon groups in hill/lower montane (950-1,100 m asl) forest in the Gunung Halimun-Salak National Park (GHSNP) from April 2008 to March 2009. The mean home range size was 37 ha and the mean daily path length was 1,180 m. The study groups spent 36% of time feeding, 41% resting, 15% traveling, 6% engaging in social behavior, and 2% in aggressive interactions. Fruit was the most important food (63% of feeding time) followed by leaves (24%), and flowers (12%). Our results suggest that Javan gibbons in higher elevation habitats have substantially larger home ranges than lowland populations, despite broad similarity in their activity budgets and diets. Conservation managers should consider the effects of altitude and habitat quality on gibbon ranging behavior when developing habitat corridors, selecting sites for translocation or reintroduction projects, and designating and managing protected areas.

Home range size in the blue-eyed black lemur ( Eulemur flavifrons): A comparison between dry and wet seasons

Western Madagascar is subjected to a long, dry winter season which coincides with food scarcity. We investigated the effect of this seasonal variation in food availability on the home ranges of blue-eyed black lemurs ( Eulemur flavifrons) in the Sahamalaza-Iles Radama National Park, north-western Madagascar. It was expected that home range would increase and overlap more in the dry season. The study was conducted in an area of dry rainforest from September 2006 to March 2008 with five lemur groups. Animals were located by direct observation and geographical locations recorded to determine the daily path length and the home range sizes of the study groups in the respective seasons. Daily path length and home range size varied significantly between seasons. Daily path length was significantly greater in the dry season (673.4 ± 539.2 m) than in the wet season (423.6 ± 183.2 m). Home ranges overlapped between groups in both seasons, but were significantly larger during the dry season (MCP: 7.5 ± 6.6 ha, 95% Kernel: 8.5 ± 6.6 ha) than in the wet season (MCP: 3.0 ± 1.6 ha, 95% Kernel: 4.1 ± 1.6 ha). There was no clear relationship between home range size and group size in either the dry or the wet season. Seasonal changes in home range area are likely to be a consequence of reduced food availability in the dry season. Compared to other primates, including some lemur species, the home range size of the blue-eyed black lemur is relatively small.

Ranging Patterns of Two Syntopic Howler Monkey Species (Alouatta guariba and A. caraya) in Northeastern Argentina

To avoid competition, ecologically similar and closely related species tend to differ in their patterns of habitat use when they live in sympatry. We compared ranging patterns of brown howler (Alouatta guariba) and black and gold howler (A. caraya) monkeys living syntopically, i.e., co-occurring and overlapping their ranges in the same habitat within the zone of sympatry, in the Atlantic Forest of northeastern Argentina with the objective of evaluating whether their use of space contributes to the avoidance of interspecific competition for food resources. During 12 mo we collected data on the ranging behavior of 2 groups of each howler species. We analyzed annual and seasonal daily path lengths and movement rates, home range size, use and overlap, habitat and vertical strata use, and intergroup encounters. Black and gold howlers traveled farther and faster during the time of relative food abundance (abundant season) than during the time of relative food shortage (lean season), and their movement rates were affected by group identity and increased with the proportion of fruits in the diet. Brown howlers’ traveling patterns were not affected by any of these factors. Home ranges for both species (95% fixed kernel; brown howlers: 31–70 ha, black-and-gold howlers: 17–112 ha) were among the largest recorded for Alouatta. For both species, core areas (50% fixed kernel) were larger for larger versus smaller groups, and decreased in the lean season compared to the abundant season. Both species showed similar patterns of habitat use, except for a slight vertical stratification. Groups of different species overlapped their ranging areas consistently more and responded to one another less aggressively during encounters than groups of the same species, suggesting that interspecific spatial niche separation for these two syntopic species is not occurring. The vertical stratification, as well as a day-to-day avoidance strategy, may be the only responses of species to one another that could reduce the potentially high levels of competition for food suggested by their elevated trophic niche overlap. A high degree of niche overlap may explain the parapatric distribution of howlers and other closely related and ecologically similar species of primates.

Small folivorous primate groups exhibit behavioral and physiological effects of food scarcity

The influence of diet and food distribution on the socioecology of group-living species has long been debated, particularly for primates. It has typically been assumed that folivorous primates experience relatively little feeding competition due to the abundant, widespread nature of their food, freeing them to form large groups in response to predation, to disperse with relative ease, and to have egalitarian female social relationships. Recent studies, however, have come to different conclusions about the extent to which folivorous primates are limited by food and experience food competition and how these factors affect folivore socioecology. To better understand the selective pressures that diet places on folivores, we investigated how 2 small highly folivorous groups of colobus monkeys (Colobus guereza) in Kibale National Park, Uganda, responded behaviorally and physiologically to a steep reduction in availability of their most important foods. The monkeys decreased their reliance on their 2 most frequently eaten food species and increased their daily path length, number of feeding patches visited/day, size of individual feeding areas, percentage of time spent feeding, and dietary diversity. They also showed evidence of physiological costs, in that lactating females' urinary C-peptide levels (i.e., insulin production) declined as top foods became scarce, and parasite loads slightly, but significantly, increased in 2 of 3 adult females examined. These results suggest that highly folivorous primates, even in very small groups, may experience behavioral and physiological effects of food limitation, within-group scramble competition for food, and possibly substantial selective pressures during periods of food scarcity. Copyright 2009, Oxford University Press.

Ranging Behavior of Proboscis Monkeys in a Riverine Forest with Special Reference to Ranging in Inland Forest

We observed a unimale group (BE-Group) of proboscis monkeys (Nasalis larvatus) comprising an α-male, 6 adult females, and several immatures from May 2005 to May 2006. We followed the group for 2014 h along the Menanggul River, Sabah, Malaysia (118°30′E, 5°30′N). Observations focused mainly on ranging behavior. We determined availability and seasonal changes in plant species consumed by the members of the group by vegetation surveys in a 2.15-ha area along 200–500 m trails in the riverine forest. During the observation period, the group ranged ≤800 m from the riverbank, within a total range of 138.3 ha. The daily path length of the group ranged from 220 to 1734 m (mean, 799 m), and daily path length correlates negatively with fruit availability. The monkeys were apt to remain within a small range in fruit-abundant seasons. Because the monkeys preferred to feed on fruits of dominant plant species in the study area, their daily path length may decrease on days when they feed on fruits. The core areas of the group’s home range were along the river because the monkeys typically returned to riverside trees to sleep. The group most often used areas that were nearer the riverbank and where the availability of fruits was higher. The most frequently used grids were the ones where the group often had sleeping sites and crossed the river. Avoiding predation may be the main reason for river crossing and selecting particular sleeping sites; hence not only food availability but also the risk of predation appears to influence the ranging of the BE-Group.

Influence of day length, ambient temperature, and seasonality on daily travel distance in the Yunnan snub‐nosed monkey at Jinsichang, Yunnan, China

This article examines the effect of ambient temperature, day length, weather conditions, and seasonality on daily path length (DPL) of a free-ranging group of Yunnan snub-nosed monkeys (Rhinopithecus bieti) using an auto-released GPS collar. Data were collected from December 17, 2003 to October 22, 2004 at Laojunshan in northwestern Yunnan province, China. The average DPL of the monkey group was 909+/-472 m (n=291), with the shortest distance being 180 m and the longest distance 3,626 m. Ambient temperature and day length were found to affect DPL. Both factors were positively correlated with DPL, which means that the monkey group traveled greater distances on longer and warmer days. At the study site, three distinct seasons were identified, and DPL did not vary significantly across these periods. The time of sunrise was not correlated with DPL. Nevertheless, we sometimes observed the group starting its daily trip later on cloudy days than on sunny days. Furthermore, weather conditions (e.g. rainy, cloudy, and sunny) did not influence the average DPL of the study group. Overall we found that the primary factors affecting DPL in R. bieti were day length and ambient temperature, especially daily highest temperature.

Bridging Gaps Between Experimental and Naturalistic Approaches in the Study of Primate Behavior

Experimental approaches are a mainstay in the study of primate behavior and functional morphology, particularly those conducted in the laboratory setting where researchers can employ a myriad of sophisticated techniques to precisely and accurately document locomotion (Demes et al. 1994, 2001; Larson and Stern 1989; Schmitt and Larson 1995; Schmidt 2005), feeding (Hylander et al. 1987; Ross et al. 2007; Vinyard et al. 2008a), and cognitive behaviors (Tomasello and Call 1997). Experimental techniques permit the isolation of extrinsic variables, allowing us to explore their effects upon primate behaviors separately as well as in combination (D'Aout et al. 2004; Vereecke et al. 2005). A tradeoff occurs in that the laboratory setting restricts choices available to study subjects. Dietary and habitat complexity in laboratory studies (by design) rarely approach those available in the natural environment (Thorpe et al. 2007). Captive animals might not be motivated to move at a pace equivalent to the pace of their free-ranging counterparts during naturalistic predator, competitor, or potential mating situations; they may never reach quite as far to select a ripe fruit. Moreover, experimental subjects are often confined to small areas, and rarely have access to natural supports and enclosures extensive enough to recreate daily path lengths, complexity of dietary choices, and overall activity levels that reflect their free-ranging counterparts (Chang et al. 1999). Natural stressors also are likely to differ from those in captivity. Food provisioning replaces the need for hours of physical activity and travel related to foraging, and may render captive animals less active, and generally less inclined or unable to behave in a way representative of conspecifics in the wild. In contrast, captive animals experience the benefits of veterinary care and their survival is less influenced by predator avoidance, seasonal food stress, parasite load and strong Int J Primatol (2008) 29:1395–1399 DOI 10.1007/s10764-008-9310-5

Ranging patterns and habitat use of Sulawesi Tonkean macaques (Macaca tonkeana) in a human‐modified habitat

The goal of this study was to investigate the ecological flexibility of Tonkean macaques (Macaca tonkeana) by examining how they respond to human-induced habitat alteration. To do so, I observed movement patterns, forest strata use, microhabitat use, and home range use in two groups that occupied habitats with different levels of human alteration and habitat quality in Lore Lindu National Park, Sulawesi, Indonesia. The group occupying the heavily altered habitat (Anca) spent a significantly greater proportion of time traveling on the ground than the group in minimally altered habitat (CH), and significantly more time than expected in microhabitats within their range that were characterized by greater alteration (e.g., agroforestry areas). There was no significant difference between the two groups in daily path length, despite differences in group size. The Anca group exhibited a greater home range area per individual than the CH group, and utilized a more limited area within their home range with greater intensity, relative to the CH group. Tonkean macaques therefore show considerable flexibility in response to anthropogenic disturbance by adjusting their use of forest strata to facilitate travel and increase foraging opportunities and by intensively using particular areas within their home range where known resources are present and predictably available.

Himalayan Semnopithecus entellus at Langtang National Park, Nepal: Diet, Activity Patterns, and Resources

Though researchers have studied lowland gray langurs extensively, there is little information about the Himalayan populations. We provide foraging data from a field study of Himalayan langurs in Langtang National Park, Nepal at 3000–4000 m elevation. Phenological records show marked seasonality in resource abundance, with extremely low availability in winter, increasing abundance in spring and monsoon, and a reduction in fall. Activity budgets indicated greater time devoted to feeding as total vegetation abundance decreased. Diet included leaf buds, ripe fruit, and evergreen mature leaves in winter; deciduous young leaves in spring; and deciduous mature leaves in the monsoon and fall. Supplemental resources, such as underground storage organs, bark, and herbaceous vegetation, were also seasonally important. Among plant part classes included in the phenological sample, abundance and consumption correlate positively for all primary food resources except evergreen mature leaves and unripe fruit. Daily path lengths varied by season and, when controlled for overall vegetation abundance, positively relate to the consumption of soft underground storage organs, fruits, and deciduous mature leaves. The results contradict the common generalization of leaves as ubiquitous or nonpatchy resources.

Diademed Sifaka (Propithecus diadema) Ranging and Habitat Use in Continuous and Fragmented Forest: Higher Density but Lower Viability in Fragments?

ABSTRACTThe mechanisms through which forest fragmentation threatens the survival of mammal populations remain poorly known, yet knowledge of this process would greatly aid conservation efforts. I investigated ranging behaviors of diademed sifakas (Propithecus diadema) in continuous and fragmented forest at Tsinjoarivo, eastern Madagascar, using focal animal observations to examine home range size, daily path length (DPL), and habitat use relative to forest edges over 12 mo. Sifaka groups in forest fragments had home ranges that were 25–50 percent as large as continuous forest groups, and moderately reduced DPLs. Continuous forest groups foraged more than expected near forest edges while fragment groups avoided edges. Fragments have higher population density than continuous forest; however, several lines of evidence suggest that fragment groups' food resources may be denser, but lower quality. Continuous forest groups appear to be energy‐maximizers, maintaining large ranges and preferentially feeding in rare fruiting trees found only in continuous forest interiors, while fragment groups appear to be time‐minimizers, using small home ranges and primarily feeding on mistletoe (a fallback food in continuous forest). Therefore, the consequences of fragmentation on long‐term viability remain unknown; it is possible that the advantage of increased density is outweighed by longer‐term demographic challenges, or other threats (e.g., nutrition, health, social behavior, disease). When animals stranded in forest fragments exhibit complex and potentially unpredictable responses, simple ecological proxies (e.g., incidence patterns and density) are probably inadequate in assessing population health and viability. Ecological study and monitoring is essential in judging the viability of fragmented populations.