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1.
Groups of black and white colobus monkeys, or guerezas (Colobus guereza), observed in the Kakamega Forest, Kenya, had weak fidelity for sleeping sites. Groups often slept in trees near commonly used food sources, which might reduce the time and energetic costs of travel. Although the home range of each group overlapped with four to seven others, groups seemed to avoid sleeping near other groups, which would give them immediate and exclusive access to nearby food sources in the morning. The number of times a species of tree was slept in was positively correlated with its density. This may have occurred because so many suitable sites were available that proximity to feeding trees could be obtained whether or not groups slept in the feeding trees. Groups slept in tall trees, which provide stable sleeping sites and which may provide protection from both aerial and ground predators. Groups were more tightly clustered on nights with greater visibility, which might reduce the risk of predation. Am. J. Primatol. 45:281–290, 1998. © 1998 Wiley-Liss, Inc.  相似文献   

2.
We studied the sleep‐related behavior of two Cao Vit gibbon (Nomascus nasutus) groups in Bangliang Nature Reserve in Jingxi County, China between January 2008 and December 2009 to test four hypotheses related to sleeping tree selection (predation avoidance, thermoregulation, food access, and range defense). Gibbons entered sleeping trees 88 ± SD 37 min before sunset before their main potential nocturnal predator become active. They usually moved rapidly and straight to sleeping trees and kept silent once settled. Over the course of the study, gibbon groups used many (87 and 57 per group) sleeping trees and reused them irregularly. They also tended to sleep in relatively tall trees without lianas, choosing small branches close to the treetop. These behaviors would make it difficult for potential terrestrial predators to detect and approach the gibbons. Therefore, these results strongly support the predation avoidance hypothesis. Gibbons tended to sleep closer to ridges than to valley bottoms and they did not sleep at lower elevations in colder months. They thus appeared not to select sleeping trees to minimize thermoregulatory stress. Gibbons very rarely slept in feeding trees, instead generally sleeping more than 100 m away from the last feeding trees of the day or the first feeding tree of the next morning. These patterns led us to reject the food access hypothesis. Lastly, we did not find evidence to support the range defense hypothesis because gibbons did not sleep in overlap areas with neighbors more often than expected based on the proportion of overlap and exclusively used areas. Am. J. Primatol. 74:998‐1005, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   

3.
Multiple ecological factors have been hypothesized to influence primate sleeping site selection. Testing multiple hypotheses about sleeping site selection permits examination of the relative strength of distinct ecological factors and expands our ability to understand how selection pressures influence primate sleeping behavior. Here we examine how avoidance of biting insects, thermoregulation, foraging efficiency, tree stability, and interspecific competition influence selection of sleeping sites by proboscis monkeys (Nasalis larvatus) in Indonesian Borneo. We collected data on relative insect abundance, temperature, rainfall, food availability, group size, sleeping site location, and presence of other primates for 12 mo. Using formal model comparison and information criteria, we analyzed the relative importance of these ecological factors in determining one aspect of sleeping site location: distance from the river. Our models supported the avoidance of biting insects and the foraging efficiency hypotheses. Proboscis monkeys slept further inland on nights when the abundance of sandflies was high along the river, and when less food was available along the river. Many studies suggest that primates select sleeping trees and locations to reduce predation risk; our study indicates that additional factors may also be important in determining sleeping site selection.  相似文献   

4.
Sleeping sites, their patterns of use, and cryptic pre-retirement behavior mitigate predation risk at sleeping sites and could influence prey fitness. We evaluated sleeping-site usage for 10 groups of golden lion tamarins (GLTs) from a population that recently suffered a substantial decline due to predation at sleeping sites. We recorded the average number of nights that groups spent at their different sleeping sites to determine whether patterns of sleeping-site use were influenced by predation risk, as measured by the rate of encounters with predators, or the availability of suitable sleeping sites, as measured by the size of a group's home range and amount of mature forest within their home range. In addition, we measured travel speed to sleeping sites and compared this speed with that recorded at other times of day. GLT groups spent more nights on average at each of their sleeping sites compared to other callitrichid species for which data are available. Predation risk and habitat characteristics were not significant predictors of how many times groups used each of their different sleeping sites. Groups significantly increased their travel speed just before entering the sleeping site. Rapid locomotion to secure tree cavities may help GLTs avoid crepuscular and nocturnal predators; however, we speculate that this strategy failed numerous GLTs in our study population during the previous decade because they used sleeping sites that were accessible to predators.  相似文献   

5.
The characteristics and availability of the sleeping sites used by a group of 27 tufted capuchin monkeys (Cebus apella nigritus) were studied during 17 months at the Iguazu National Park, Argentina. We tested different hypotheses regarding possible ultimate causes of sleeping-site selection. Most sleeping sites were located in areas of tall, mature forest. Of the 34 sleeping sites the monkeys used during 203 nights, five were more frequently used than the others (more than 20 times each, constituting 67% of the nights). Four species of tree (Peltophorum dubium, Parapiptadenia rigida, Copaifera langsdorfii and Cordia trichotoma) were the most frequently used. They constituted 82% of all the trees used, though they represent only 12% of the trees within the monkeys' home range which had a diameter at breast height (DBH) > 48.16 cm (1 SD below the mean DBH of sleeping trees). The sleeping trees share a set of characteristics not found in other trees: they are tall emergent (mean height +/- SD = 31.1+/-5.2 m) with large DBH (78.5+/-30.3 cm), they have large crown diameter (14+/-5.5 m), and they have many horizontal branches and forks. Adult females usually slept with their kin and infants, while peripheral adult males sometimes slept alone in nearby trees. We reject parasite avoidance as an adaptive explanation for the pattern of sleeping site use. Our results and those from other studies suggest that predation avoidance is a predominant factor driving sleeping site preferences. The patterns of aggregation at night and the preference for trees with low probability of shedding branches suggest that social preferences and safety from falling during windy nights may also affect sleeping tree selection. The importance of other factors, such as seeking comfort and maintaining group cohesion, was not supported by our results. Other capuchin populations show different sleeping habits which can be explained by differences in forest structure and by demographic differences.  相似文献   

6.
Several factors are likely to control sleeping site selection and presleep behavior in nonhuman primates, including predation risk and location of food resources. We examined the effects of these factors on the sleeping behavior of northern pigtailed macaques (Macaca leonina). While following a troop living in the surroundings of the Visitor Center of Khao Yai National Park (Thailand), we recorded the physical characteristics and location of each sleeping site, tree, the individuals' place in the tree, posture, and behavior. We collected data for 154 nights between April 2009 and November 2010. The monkeys preferred tall sleeping trees (20.9 ± SD 4.9 m) and high sleeping places (15.8 ± SD 4.3 m), which may be an antipredator strategy. The choice of sleeping trees close to the last (146.7 ± SD 167.9 m) or to the first (150.4 ± SD 113.0 m) feeding tree of the day may save energy and decrease predation risk when monkeys are searching for food. Similarly, the choice of sleeping sites close to human settlements eases the access to human food during periods of fruit scarcity. Finally, the temporal pattern of use of sleeping sites, with a preference for four of the sleeping sites but few reuses during consecutive nights, may be a trade‐off between the need to have several sleeping sites (decreasing detection by predators and travel costs to feeding sites), and the need to sleep in well‐known sites (guaranteeing a faster escape in case of predator attack). Am. J. Primatol. 73:1222–1230, 2011. © 2011 Wiley Periodicals, Inc.  相似文献   

7.
We investigated the sleeping site ecology of two sympatric mouse lemur species (Microcebus murinus and M. ravelobensis) in northwestern Madagascar during the second half of the dry season with respect to the type, quality, and usage pattern of the sleeping sites, as well as to social sleeping habits and response to potential threats. The type and quality of the sleeping sites differed between the two species. M. murinus used protected wooden shelters (tree holes) more frequently than M. ravelobensis, and M. ravelobensis used a broader variety of less protected sites (e.g., branches, lianas, and leaves) than M. murinus. Whereas male M. murinus usually slept alone, and female M. murinus mostly slept in groups, both sexes of M. ravelobensis slept in mixed-sex sleeping groups. M. murinus relied on crypsis in their sleeping sites, whereas M. ravelobensis regularly showed a flight response to the approach of an observer. This behavioral difference could indicate an adaptation to a higher predation risk in less protected sleeping sites. Whereas female M. murinus showed a high site fidelity, male M. murinus and both sexes of M. ravelobensis frequently changed their sleeping sites, which may also be interpreted as an antipredator strategy. The results are discussed with respect to three possible ecological explanations: interspecies competition, restricted resource availability, and niche differentiation. The latter is the most likely explanation for these interspecific differences.  相似文献   

8.
In this 3-year investigation we documented patterns of density, diet, and activity of red colobus monkeys (Procolobus tephrosceles) in six areas in or near Kibale National Park, Uganda and related these patterns to availability of food resources. There were large differences in the density and behavior of the red colobus among the sites. For example, the red colobus at one site with a diverse plant community of more than 61 tree species, had a diet that included at least 42 species. In contrast, at a second site red colobus spent 92% of their feeding time eating from one species that dominated the tree community. The density of important red colobus food trees varied among sites from 32 trees/ha to 204 trees/ha, and red colobus density ranged from 0.70 groups/km2 to 7.41 groups/km2. Among sites, red colobus density was related to the cumulative DBH of important food trees, when one apparently anomalous site was excluded, and populations with more plant species in their diets tended to be those that were found at higher densities. Activity budgets of the red colobus populations varied markedly among sites. For example, feeding time ranged among sites from 29 to 55%, and traveling varied from 5 to 20%. When faced with increased foraging demands, red colobus reduced the time spent resting, while the time spent socializing remained fairly constant. Comparative socioecological studies typically contrast species separated by large geographical distances to ensure there is sufficient variation in the environment to detect behavioral responses. The marked differences in ecological conditions and red colobus behavior we documented over short geographical distances, suggests that small-scale contrasts are a useful tool to examine ecological determinants of behavior and community structure.  相似文献   

9.
Arboreal primates spend about half of their lives at sleeping sites; hence, selection of sleeping sites is crucial for individual survival, and data concerning them is important for conservation efforts. We collected data on sleeping sites for a group of the endangered snub-nosed monkey (Rhinopithecus brelichi) at Yangaoping (27°58′N, 108°45′E) from January 2006 to December 2007. All sleeping sites were located in the mid-slope and in the shadow of ridges facing the northeast and southeast. The monkeys remained quiet while entering and occupying sleeping sites, and slept in evergreen species during the cold season (December–March). Trees in sleeping sites were similar in height and girth at breast height to those elsewhere, but some trees in lower areas were larger. The monkeys usually slept in close proximity to the last feeding spot, and their daily activities usually occurred around the sleeping site. Areas adjacent to sleeping sites were used more intensively than those not adjacent. Monkeys left the sleeping sites later in the morning in the cold season. These behavioral responses suggested that predation risk, thermoregulation, and climate stresses are the main determining factors in the selection of sleeping sites for this temperate monkey.  相似文献   

10.
Sleeping sites are an important aspect of an animal's ecology given the length of time that they spend in them. The sleep ecology of wild saddleback and mustached tamarins is examined using a long-term data set covering three mixed-species troops and 1,300+ tamarin nights. Seasonal changes in photoperiod accounted for a significant amount of variation in sleeping site entry and exit times. Time of exit was more closely correlated with sunrise than time of entry was with sunset. Both species entered their sleeping sites when light levels were significantly higher than when they left them in the morning. Troops of both species used >80 individual sites, the majority being used once. Mustached tamarins never used the same site for more than two consecutive nights, but saddlebacks reused the same site for up to four consecutive nights. Mustached tamarins slept at significantly greater heights than saddleback tamarins. There were consistent interspecific differences in the types of sites used. Neither the presence of infants, season, nor rainfall affected the types or heights of sites chosen. Sleeping sites were located in the central area of exclusive use more often than expected, and their position with respect to fruiting trees indicated a strategy closer to that of a multiple central place forager than a central place forager. These findings are discussed in light of species ecology, with particular reference to predation risk, which is indicated as the major factor influencing the pattern of sleeping site use in these species.  相似文献   

11.
Seasonal changes may have a strong effect on the safety of sleeping sites in arboreal primates. For example, changes in vegetation thickness may impact predation risk and energy expenditure related to thermoregulation. We investigated how seasonality influenced sleeping site characteristics and usage pattern in an arboreal primate living in a highly seasonal environment. The western woolly lemur (Avahi occidentalis) lives in the dry deciduous forest of northwestern Madagascar, where leaf coverage greatly varies across the year. We examined the hypothesis that these lemurs change their sleeping site behavior dependent on season. We collected data on sleeping site height and location, and characterized usage patterns in six radiotagged pairs between May and December 2008. During the late dry season, pairs preferentially slept in the middle part of a tree. In contrast, there was no height preference during the early rainy season. The lemurs used more sleeping sites during the early rainy than during the late dry season and stayed more days at the same sleeping tree in the late dry season. Our findings support the hypothesis that season affects sleeping site selection in an arboreal primate species living in a highly seasonal environment. During the late dry season, western woolly lemurs are particularly conspicuous to hunters and we therefore suggest a better monitoring of the forest in this season to guarantee their future survival.  相似文献   

12.
Selection of sleeping trees in pileated gibbons (Hylobates pileatus)   总被引:1,自引:0,他引:1  
Selection and use patterns of sleeping sites in nonhuman primates are suggested to have multiple functions, such as predation avoidance, but they might be further affected by range defense as well as foraging constraints or other factors. Here, we investigate sleeping tree selection by the male and female members of one group of pileated gibbons (Hylobates pileatus) at Khao Ang Rue Nai Wildlife Sanctuary, Thailand. Data were collected on 113 nights, between September 2006 and January 2009, yielding data on 201 sleeping tree choices (107 by the female and 94 by the male) and on the characteristics of 71 individual sleeping trees. Each sleeping tree and all trees ≥40 cm diameter at breast height (DBH) in the home range were assessed (height, DBH, canopy structure, liana load) and mapped using a GPS. The gibbons preferentially selected tall (mean=38.5 m), emergent trees without lianas. The majority of the sleeping trees (53.5%) were used only once and consecutive reuse was rare (9.5%). Sleeping trees were closer to the last feeding tree of the evening than to the first feeding tree in the morning, and sleeping trees were located in the overlap areas with neighbors less often than expected based on time spent in these areas. These results suggest avoidance of predators as the main factor influencing sleeping tree selection in pileated gibbons. However, other non‐mutually exclusive factors may be involved as well. Am. J. Primatol. 72:617–625, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

13.
We collected data on sleeping site use of the François’ langur (Trachypithecus francoisi) between August 2003 and July 2004 at Nonggang Nature Reserve, China. We tested hypotheses regarding possible ultimate causes of sleeping site selection in light of our results. Langurs selected the ledges and caves on cliffs as sleeping sites. Of 23 identified sleeping sites, 7 were more frequently used than the others (≥9 times each, accounting for 64% of total observed nights). Langurs used most sleeping sites repeatedly, and reused some of them on consecutive nights; 4 consecutive nights were the longest run. We suggest that langurs choose sleeping sites to make approach and attack difficult by predators, and to increase familiarity so as to improve chances for escape. Langurs’ cryptic behaviors before entering sleeping sites and the rapid movement toward sleeping sites (4 min on average) with an increased level of vigilance may help to decrease the possibility of detection by predators. Access to food appears to have a profound influence on sleeping site selection in François’ langurs, as demonstrated by the langurs’ tendency to select sleeping sites close to their current main feeding sites. The position of sleeping site relative to the last feeding site of the day and the first feeding site of the subsequent morning indicated a strategy closer to that of a multiple central place forager than of a central place forager. Our results do not support the influences of other factors, e.g., avoidance of parasites, seeking comfort, and range or resource defense, on sleeping site selection.  相似文献   

14.
Hamadryas baboons sleep on cliffs throughout their range, and this can be attributed to the safety cliffs provide against predators in the absence of tall trees. In this paper, we report the first documented occurrence of hamadryas baboons sleeping in doum palm trees rather than on cliffs. Data derive from a study of hamadryas baboons at the Filoha site in lowland Ethiopia. During all-day follows, data were collected on travel patterns, band activity, and location. Variation in the baboons' home range was characterized using vegetation transects. We discovered that one band in this population, Band 3, occasionally slept in doum palm trees (Hyphaene thebaica). The palm tree sleeping site differed from other palm fragments in the baboons' home range in that it contained a higher density of palm trees. Possible factors influencing this unique use of palm trees as a sleeping site include access to palm fruit, avoiding contact with Afar nomads, avoiding sharing sleeping cliffs with other bands, protection from predators, and the lack of cliffs in a section of the baboons' home range. Evidence from this study suggests that the palm tree sleeping site is used because it affords better protection from predators than other palm fragments in an area of the band's home range that does not contain cliffs.  相似文献   

15.
Tamarin monkeys, of the genus Saguinus , spend over half their lives at arboreal sleeping sites. The decision as to which site to use is likely to have considerable fitness consequences. These decisions about sleeping sites by three troops of golden-handed tamarin Saguinus midas midas were examined over a 9-mo period at a rainforest site in French Guiana. Data are presented on the physical nature of sleeping sites, their number, position within home ranges, and pattern of use and reuse, aspects of behaviour at retirement and egress, and predation attempts on the study troops. Cumulative plot analysis indicated that a tamarin troop used 30–40 sleeping sites in a 100-day period, approximately half of which were used very infrequently, so that consecutive reuse was never greater than three nights. Sleeping trees were superior in architectural parameters and liana weight to non-sleeping trees. There were no more sleeping sites than expected within the home range boundary region of the tamarins or in areas of overlap with the home ranges of neighbouring troops. Tamarins selected sleeping sites nearest to the last feeding site of the day on 25% of occasions. The study troops engaged in a number of activities that may reduce predation risk; raptor attacks on the study troops over 9 mo were frequent but unsuccessful. Tamarins often visited a sleeping site several hours before arrival, and were more likely to visit a site before use if they had not used it recently. The decision to select a sleeping site therefore involved knowledge of the previous frequency of use of that site.  相似文献   

16.
Primates require secure sleeping sites for periods of rest, but despite their importance, the characteristics of desired sleeping sites are poorly known. Here we investigated the sleeping ecology of a radio-collared population of the Sambirano mouse lemur, Microcebus sambiranensis, during the nonreproductive season in the Anabohazo forest, northwestern Madagascar. We also investigated their ranging behavior and examined the spatial distribution of sleeping sites within the home ranges of the collared individuals. We took measurements of the sleeping tree’s physical characteristics and recorded the number of collared individuals using each sleeping site. We found that M. sambiranensis generally use foliage sleeping sites more frequently than tree holes and individuals slept more frequently in densely foliated trees than in sparsely foliated trees, often alone. We observed no significant differences in home range size or nightly travel distance between males and females; however, home ranges were smaller than those described for other mouse lemur species. Finally, we found that M. sambiranensis sleep peripherally and forage centrally within their home ranges, a behavior not previously described for mouse lemurs. Our results indicate profound differences in the social organization between M. sambiranensis and other mouse lemur species described in the literature, suggesting species-specificity in mouse lemur ecology. Understanding the sleeping ecology and ranging behavior of mouse lemurs is of great importance to their conservation, as these data facilitate the planning of long-term reforestation, habitat management, and population assessment.  相似文献   

17.
The behavior of spider monkeys (Ateles geoffroyi) at sleeping sites and the characteristics of these sites were studied in Santa Rosa National Park, Costa Rica. The spider monkeys tended to congregate just prior to dusk at a number of sleeping sites which were repeatedly used (81.6%), but occasionally they slept in trees which were only used once (18.4%). All of the regularly used sleeping trees were not used concurrently, but rather, there was a rotation between sites. In general, males were not encountered at regularly used sleeping sites as often as other age/sex classes, and when they were in all male subgroups, they did not sleep in repeatedly used sites. The trees used as regular sleeping sites tended to be large, but such trees were common in the group's home range. The size of the subgroups attending repeatedly used sleeping trees was large when food was abundant and small when food was scarce. It is suggested that this relationship reflects that the costs of travelling to the sleeping site would be more easily recovered when food was abundant than when food was scarce.  相似文献   

18.
Sleeping sites may be beneficial for animals in terms of thermoregulation, proximity to foraging sites, and protection from predators and infectious diseases. The abundance of adequate sleeping sites is thus essential for the survival of primates. We investigated microhabitats around sleeping sites, and the influence of habitat degradation on sleeping site choice and usage, in the nocturnal Sahamalaza sportive lemur, Lepilemur sahamalazensis. We used quarter point sampling (N?=?315) to describe five forest fragments and 57 sleeping sites and continuous focal animal sampling (N?=?45) to determine the diurnal activity budget, to determine whether individuals inhabiting different fragments or sleeping site types showed different levels of vigilance. Our results suggest that tall trees with large crowns, a high density of small trees, and dense canopy are particularly important for sleeping site choice. Microhabitat structure around sleeping sites did not differ between forest fragments or sleeping site types. Diameter at breast height, crown diameter, canopy cover, and bole height were similar for all sleeping trees, as were the number of lianas in trees with tree-tangle sleeping sites, and the volume of tree holes. Tree holes used as sleeping sites were most often found in dead trees of Bridelia pervilleana (50–62.5 %), whereas tree tangle sites were most often located in Sorindeia madagascariensis (20–62.5 %). Lemurs were active 5–14 % of the daytime, although they never left their sleeping sites or fed. Individuals occupying tree holes had higher levels of activity than those in tree tangles, and those in more degraded fragments were more active. Our results suggest that Sahamalaza sportive lemurs choose their sleeping sites according to specific habitat characteristics, and that factors associated with old and intact forest are likely to be crucial for their survival.  相似文献   

19.
Between 1984 and 1987, we recorded the sleeping-site and lodge tree preferences of night monkeys at the Beni Biological Station, Bolivia. We characterized the structure of sleeping-site compared lodge trees to nonlodge trees, and determined the frequency of their use. Aotus azarae used branch and liana platforms on trees of the middle strate of the forest as sleeping sites, but the lodge trees provided sparse cover. Monkeys may manipulate either natural accumulations of material or bird nests to serve as sleeping sites. The characteristics of the sleeping site and of the lodge trees may be related to protection against predators and to thermal advantages. The distribution of lodge trees appeared to be related to access to food. Activities around the sleeping site could be related to marking behavior.  相似文献   

20.
We examined the spatial and temporal distribution of the foods of ursine colobus (Colobus vellerosus) at Boabeng-Fiema, Ghana as a means to predict the monopolizablity and usurpability of their food resources. Recent evidence suggests that food may not be limiting for folivorous primates, and that male sexual coercion may be a more important influence on folivore social organization. To address the question, we collected focal data on the feeding behavior of adult females and males over 11 mo (September 2000-August 2001) on 2 groups: WW (n = 31–33 individuals) and B (n = 8–16 individuals). We also conducted phenological monitoring and a tree survey of the two-group home ranges to establish food availability and distribution. We used 2 behavioral or organism-defined indicators of feeding behavior to assess potential resource contestability: food site residence time and distance moved between food sites. The colobus fed on a high diversity of species, most of their food trees were not clumped in distribution, within-tree interfood distances were short, and food trees were large. The only condition associated with the potential for monopolization was low food tree density. However, low food tree density may be offset by the colobus’ use of large trees. Taken together, the ecological and behavioral indicators suggest the food resources of Colobus vellerosus had a low potential for monopolization. Our results also indicate mature leaves had the longest food site residence time, which may suggest they should be the most usurpable plant part, though their presumed low quality and high abundance probably counteracted the effect. The pattern implied the potential for direct feeding competition among Colobus vellerosus at Boabeng-Fiema was low and agonistic interactions over food are not expected. Instead, a group size effect on feeding efficiency should be a more predominant influence on feeding efficiency, if food is limiting for the species.  相似文献   

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