Ranging of <Emphasis Type="Italic">Rhinopithecus bieti</Emphasis> in the Samage Forest,China. I. Characteristics of Range Use

We quantified the home range and explored the style of ranging of black-and-white snub-nosed monkeys (Rhinopithecus bieti) in the subtropical-temperate montane Samage Forest (part of Baimaxueshan Nature Reserve) in the vicinity of Gehuaqing. Over 14.5 mo, we took positional records of the study band via a GPS receiver at 30-min intervals, and found that they covered an area of 32 km². Over a 10-yr period, the group even ranged in an area of 56 km², which is among the largest home range estimates for any primate. The large home range was probably due to the combined effects of large group size (N > 400) and forest heterogeneity, with seasonally food-rich areas interspersed with less valuable areas. The subjects did not use their home range uniformly: 29% of the grid cells had more location records than expected based on a uniform distribution, thus representing a core area, albeit a disjunct one. A continuous 1-mo group follow in the fall revealed that the band traveled on average 1.62 km/d and that days of concentrated use of a particular forest block were followed by more extensive marches. Neither climate nor human disturbance parameters correlate significantly with monthly estimates of the group’s home range size. Even though there is no significant correlation between temporal availability of plant phenophases and range size, our observations implicate temporal and spatial availability of food as a determinant of home range use of the focal group. Winter, spring, and summer home ranges are equally large: 18.2, 17.8, and 18.6 km², respectively. Home range decreased markedly in fall (9.3 km²), probably because the band obtained sufficient food resources (fruit) in a smaller area. The large winter range is best attributed to the exploitation of dispersed clumped patches of mature fruits. Cyril C. Grueter and∙Dayong Li contributed equally to the paper.     

Social Organization and Range Use in the Yunnan Snub-Nosed Monkey Rhinopithecus bieti

We studied social organization, behavior, and range use of the Yunnan snub-nosed monkey (Rhinopithecus bieti) at Wuyapiya (99°12E, 28°30N, the People's Republic of China) over 12 months between May 1992 and June 1994. The Wuyapiya band contained 175 members and had two levels of social organization. At one level, the monkeys formed multifemale, one-male units (OMUs) similar to those of many other colobines. At another level, 15 to 18 OMUs traveled together in a cohesive band. Unlike the bands of other species of Rhinopithecus, the Wuyapiya band of R. bieti did not show seasonal fission–fusion, although some social behavior, such as male–male aggression, was seasonal. With regard to range use, the Wuyapiya band had a large home range and long daily travel distances compared with other colobines. Minimum range size in 1 year at Wuyapiya is 16.25 km ² , although there is no asymptote for range size as a function of observation time. Range size for the Wuyapiya band is 25.25 km ² over the 2-year study and appeared to cover 100 km ² between 1985 and 1994. The primary food of R. bieti at Wuyapiya is lichens, which are ubiquitous in fir trees. The multitiered social organization of R. bieti appears to result from the interaction of food resource characters with the forces of mate competition, with band sizes based on female responses to the spatial and temporal characteristics of lichens and subdivisions within bands based on male competition for mates.     

Dietary Profile of <Emphasis Type="Italic">Rhinopithecus bieti</Emphasis> and Its Socioecological Implications

To enhance our understanding of dietary adaptations and socioecological correlates in colobines, we conducted a 20-mo study of a wild group of Rhinopithecus bieti (Yunnan snub-nosed monkeys) in the montane Samage Forest. This forest supports a patchwork of evergreen broadleaved, evergreen coniferous, and mixed deciduous broadleaved/coniferous forest assemblages with a total of 80 tree species in 23 families. The most common plant families by basal area are the predominantly evergreen Pinaceae and Fagaceae, comprising 69% of the total tree biomass. Previous work has shown that lichens formed a consistent component in the monkeys’ diet year-round (67%), seasonally complemented with fruits and young leaves. Our study showed that although the majority of the diet was provided by 6 plant genera (Acanthopanax, Sorbus, Acer, Fargesia, Pterocarya, and Cornus), the monkeys fed on 94 plant species and on 150 specific food items. The subjects expressed high selectivity for uncommon angiosperm tree species. The average number of plant species used per month was 16. Dietary diversity varied seasonally, being lowest during the winter and rising dramatically in the spring. The monkeys consumed bamboo shoots in the summer and bamboo leaves throughout the year. The monkeys also foraged on terrestrial herbs and mushrooms, dug up tubers, and consumed the flesh of a mammal (flying squirrel). We also provide a preliminary evaluation of feeding competition in Rhinopithecus bieti and find that the high selectivity for uncommon seasonal plant food items distributed in clumped patches might create the potential for food competition. The finding is corroborated by observations that the subjects occasionally depleted leafy food patches and stayed at a greater distance from neighboring conspecifics while feeding than while resting. Key findings of this work are that Yunnan snub-nosed monkeys have a much more species-rich plant diet than was previously believed and are probably subject to moderate feeding competition.     

Sleeping sites of <Emphasis Type="Italic">Rhinopithecus bieti</Emphasis> at Mt. Fuhe,Yunnan

Data on sleeping site selection were collected for a group of black-and-white snub-nosed monkeys (Rhinopithecus bieti; around 80) at Mt. Fuhe, Yunnan, China (99°20E, 26°25N, about 3,000 m asl) from November 2000 to January 2002. At the site mainly three vegetation types were present in an elevation-ascending order: deciduous broad leaf forest, mixed coniferous and broad leaf forest, and dark coniferous forest. In addition, bamboo forest presented in areas burned in 1958. Sleeping sites (n =10) were located in the coniferous forest, where trees were the tallest, bottommost branches were the highest, the diameter of crowns was the second largest, and the gradient of the ground was the steepest. Monkeys usually kept quiet during entering and staying at a sleeping site. The site choice and the quietness may be tactics to avoid potential predators. In the coniferous forest, however, monkeys did not sleep in the valley bottom where trees were the largest, but frequently slept in the middle of the slope towards the east/southeast, in the shadow of ridges in three other directions, to avoid strong wind and to access sunshine; in winter-spring, they ranged in a more southern and lower area than in summer-autumn. These may be behavioral strategies to minimize energy stress in the cold habitat. Monkeys often slept in the same sleeping site on consecutive nights, which reflected a reduced pressure of predation probably due to either the effectiveness of anti-predation through sleeping site selection, or the population decline of predators with increasing human activities in the habitat. The groups behavioral responses to interactive and sometimes conflicting traits of the habitat are site-specific and conform to expectations for a temperate zone primate.     

唐家河国家级自然保护区川金丝猴生境适宜性评价

生境适宜性评价是濒危物种保护的重要基础。川金丝猴（Rhinopithecus roxellana）是栖息于温带森林的、中国特有的珍稀灵长类动物。位于岷山山系的四川唐家河国家级自然保护区是川金丝猴的重要分布地之一,但涉及该地区川金丝猴的生境信息却较缺乏。运用最大熵（Maximum entropy,MaxEnt）模型对四川唐家河国家级自然保护区川金丝猴不同季节的生境适宜性进行了研究,发现四个季节的训练集和验证集的受试者工作特征曲线下面积（Area under the receiver operator characteristic curve,AUC）值均超过0.8,说明模型预测结果较好。结果显示：（1）影响不同季节川金丝猴分布的主要因子是海拔、河流和道路。（2）川金丝猴的适宜生境面积存在季节性变化。其中,春季的适宜生境面积最大,为233.94 km²,占全区面积的58.48%;夏季的次之,为192.75 km²,占48.19%;秋冬季的适宜生境面积相对较低,分别为145.54 km²（占36.39%）和142.63 km²（占35.66%）。（3）川金丝猴的适宜生境分布具有明显的季节性垂直变化。研究揭示保护好完整的森林植被带对川金丝猴的生存具有重要意义,尤其要重视对人为干扰较强的低海拔生境的保护。     

云南拉沙山黑白仰鼻猴对种子传播潜力的评估

灵长类是森林生态系统中植物种子的主要传播者,有助于森林植被的更新,然而受研究方法的限制,灵长类种子传播潜力常被低估。为全面评估温带灵长类动物的种子传播潜力,采用直接观察法和粪便分析法评估珍稀濒危灵长类动物黑白仰鼻猴的种子传播潜力。于2018年11月—2019年10月采用直接观察法(瞬时扫描取样法)收集云岭省级自然保护区拉沙山黑白仰鼻猴的活动时间分配数据,获取每月取食果实的比例;同时每月收集黑白仰鼻猴的粪便,采用粪便分析法分拣猴粪中残留的植物种子,统计有完整种子残留的月份和粪便比例,应用这两种方法评估黑白仰鼻猴种子传播潜力及其差异。结果表明：直接观察法收集到黑白仰鼻猴取食果实的月份数为6个月(7—12月),月均取食果实的比例为(15.31±20.15)%,共取食13种果实;而粪便分析法发现黑白仰鼻猴粪粒内全年都有完整种子残留,粪便中月均完整种子残留比例(35.19±35.43)%,其中9月至第二年1月粪便中种子残留比例都大于50%,共取食18种果实;综合两种方法发现云南拉沙山黑白仰鼻猴共取食20种植物果实,具有较高的种子传播潜力。直接观察法可确定黑白仰鼻猴取食果实的物种数,而粪便分析法能...     

Ranging of <Emphasis Type="Italic">Rhinopithecus bieti</Emphasis> in the Samage Forest,China. II. Use of Land Cover Types and Altitudes

We investigated composition and structure of a temperate montane forest called Samage at Baimaxueshan National Nature Reserve in Yunnan, one of the last refuges for the highly endangered black-and-white snub-nosed monkeys (Rhinopithecus bieti). There is a patchwork of vegetation types at Samage, and we distinguished 6 major land cover types within the home range of the focal group. We tracked the semihabituated Gehuaqing band for a full annual cycle to study their habitat utilization and altitudinal ranging. We analyzed the group’s selective use of particular habitat types via selection ratios. We calculated habitat availability from a GIS database. We found that they used mixed deciduous broadleaf/conifer forest disproportionately to its availability in all months. Subjects completely avoided meadows. Pine and evergreen broadleaf forests acted as corridors between patches of mixed forest and monkeys visited them occasionally, but at low frequencies and mostly in transit. The focal band stayed at elevations ranging from ca. 2600 m to 4000 m, and the mean elevation used is 3200 m. We found evidence for seasonal variation in use of elevational zones. The band stayed at significantly higher elevations in summer than in spring. The descent in spring was likely related to a flush of immature leaves at low-lying elevations. Availability of preferred fruits also had a highly positive influence on altitudinal ranging, i.e., during months with high fruit availability (late summer, early fall), the band stayed at medium elevations where preferred fruits were most abundant. Higher concentrations of lichens and the snub-nosed monkeys’ search for not yet depleted fruits probably caused them to remain at mid-elevations in winter. There is no significant correlation between climate parameters and elevation used. One of the main inferences of this investigation is that, contrary to previous accounts, Rhinopithecus bieti is not universally associated with high-elevation dark fir forest, but at Samage exhibits an overwhelming preference for mixed forest. Moreover, our analyses support the hypothesis that elevational migration, in this temperate-subtropical forest, is influenced by the temporal fruiting of major food trees and that climate has only a negligible effect on elevation use. Dayong Li and Cyril C. Grueter contributed equally to the paper.     

Identification of 13 Human Microsatellite Markers via Cross-species Amplification of Fecal Samples from Rhinopithecus bieti

Yunnan snub-nosed monkeys (Rhinopithecus bieti) are 1 of 3 snub-nosed monkey species endemic to China. Only ca. 1500 individuals remain in high-altitude forests 3000–4500 m above sea level on the Tibetan Plateau, making them the nonhuman primate living at the highest known elevation. It is one of the most endangered 25 primate species in the world. Proper knowledge of the population genetics and social system of Rhinopithecus bieti will contribute to more appropriate conservation management decisions. Cross-species amplification of human microsatellite loci has facilitated analysis of the population genetics and reproductive strategies of various primate species. We screened 72 human-derived markers to assess their utility in Yunnan snub-nosed monkeys. Thirteen of them produced reliable results and exhibited moderate levels of polymorphism.     

Winter Feeding Tree Choice in Sichuan Snub-Nosed Monkeys (Rhinopithecus roxellanae) in Shennongjia Nature Reserve,China

We investigated patterns of winter feeding tree choice in 4 groups of Sichuan snub-nosed monkeys (Rhinopithecus roxellanae) in Shennongjia Nature Reserve, China. We collected data during 2 winters from 1998 to 2000. The monkeys used mature forest, young forest and shrub forest, but not grassland. Groups used tree species in a significantly nonrandom pattern. There was a similar composition of preferred tree species between different habitats for each group and among the same habitat types for different groups. They preferred Abies fargesii, Pinus armandii and Salix walliciana for foraging. The 3 species occur in varying degrees of abundance in different habitats and were used differently by the 4 groups. The difference is probably due to interhabitat differences in availability of tree species, in addition to microclimate. The mean circumference of a tree had little effect on its preference score, but preferred species tend to be larger. A Wilcoxon signed-rank test indicated that the percentage of trees used and average number of feeding bites per tree is significantly greater for larger trees. For all trees in a given habitat, the percentage of trees used and average number of bites per tree have a significant positive correlation with average tree circumference. Our results indicate that Rhinopithecus roxellanae prefer to feed in large trees more than small trees in a given habitat, thereby preferring mature forest habitat. There is also a group-size effect; larger groups used higher-quality habitats than those of smaller groups. Both tree species and size are the major determinants of feeding choice, but tree species is more important than tree size. Our results have at least three implications for winter habitat conservation of Sichuan snub-nosed monkeys. Conservation efforts should be focused on mature forest because it is better habitat at Rhinopithecus than young forest, as long as the same tree species are present. Secondly, Pinus armandii, Abies fargesii and Salix walliciana should be conserved as top priority in forest communities. Third, the largest trees in each habitat should be given greatest possible protection.     

Comparison of masticatory morphology between Rhinopithecus bieti and R. roxellana

The masticatory apparatus for two endemic species of golden monkey in China, Rhinopithecus bieti and Rhinopithecus roxellana, were compared with those of macaques, Macaca and leaf monkeys, Presbytis. Multivariate analyses demonstrated that the two golden monkey species are distinct. Interspecies allometric analyses revealed that golden monkeys differ in their masticatory apparatus from both macaques and leaf monkeys. The prominent symphysial fusion, corpus, and sagittal condylar dimension of R. roxellana may produce efficient biting force on the incisal and posterior canine teeth, with the heavy reaction force born on the temporomandibular joint. However, the well-developed bizygamatic width and mandibular height in R. bieti suggest that posterior canine function is similarly prominent in R. roxellana, while incisal function is not. © 1995 Wiley-Liss, Inc.     

Phylogeny of Snub-Nosed Monkeys Inferred from Mitochondrial DNA,Cytochrome B,and 12S rRNA Sequences

Snub-nosed monkeys (Rhinopithecus spp.) are confined to isolated mountainous regions in China and North Vietnam. Their systematic classification and phylogenetic relationship has been controversial. The structures of mitochondrial DNA cytochrome b and 12S rRNA show that the 4 species of Rhinopithecus are quite different from other colobines. It is reasonable to regard them as an independent genus, as determined by external features, morphometric characters and behavior. However, whether or not there should be a subdivision between the Vietnamese and Chinese species at the subgeneric level remains to be clarified; more evidence from a large range of Asian colobine species is needed. The Guizhou species, Rhinopithecus brelichi, is a valid species, which is more closely related to Pygathrix than the other species ( R. roxellana, R. bieti and R. avunculus) are. Results also indicate that 3 species—Rhinopithecus roxellana, R. bieti and R. avunculus—might have diverged from R. brelichi, but the phylogenetic relationship of R. avunculus is not clear.     

Effects of Seasonal Folivory and Frugivory on Ranging Patterns in <Emphasis Type="Italic">Rhinopithecus roxellana</Emphasis>

The distribution of food resources in time and space may affect the diet, ranging pattern, and social organization of primates. We studied variation in ranging patterns in a group of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) over winter and summer in response to variation in their diet in the Qingmuchuan Nature Reserve, China. There was a clear diet shift from highly folivorous in winter to highly frugivorous in summer. The home range was 8.09 km² in summer and 7.43 km² in winter, calculated via the 95% kernel method. Corresponding to the diet shift, the focal group traveled significantly longer distances in summer (mean 1020 ± 69 m/d) than in winter (mean 676 ± 53 m/d); the daily range was also significantly greater in summer (mean 0.27 ± 0.02 km²/d) than in winter (mean 0.21 ± 0.01 km²/d). There was no significant variation in home range size between winter and summer, and the monkeys did not use geographically distinct ranges in summer and winter. However, overlap in the actual activity area and core range between winter and summer was only 0.13 km², representing 4.4% of the summer core area and 5.3% of the winter core area. Differences were apparent between summer and winter ranging patterns: In summer, the group traveled repeatedly and uninterruptedly across its home range and made 3 circles of movement along a fixed route in 31 d; in winter, the activity area was composed of 3 disconnected patches, and the focal group stayed in each patch for an average of 8 successive days without traveling among patches. Winter range use was concentrated on mixed evergreen and deciduous forest patches where leaves and fruits were available, whereas the summer range pattern correlates significantly positively with the distribution of giant dogwood (Cornus controversa) fruits. Thus it appears that the diet shift of Sichuan snub-nosed monkeys between winter and summer caused the monkeys to use their home range in different ways, supporting the hypothesis that food resources determine primate ranging patterns.     

Report on the distribution,population, and ecology of the yunnan snub-nosed monkey (Rhinopithecus bieti)

The Yunnan snub-nosed monkey (Rhinopithecus bieti), an endangered species in China, has received more protection in theory than in practice. Therefore it is on the very verge of extinction. The population of the species was estimated less than 2,000 individuals spread in 19 distinct groups. It was confirmed that the monkey was confined to the Yunling Mountain System, the area between the Yangtze River (Changjiang, aka Jinshajiang) to the east and the Mekong River (Lancangjiang) to the west. We further concluded that a lowland belt to the east, about 100 km long and 20 – 30 km wide was not suitable habitat for the monkeys, and appeared to serve as the natural ecogeologic barrier for the species. Our results indicated that the southern limit of the distribution was at Longma (26°14′N), and that the northern limit of the distribution was at Xiaochangdu (29°20′N). The distribution area of the species was substantially smaller than previously estimated. There were substantial ecological differences between the southern and northern parts of the species range. The monkey was found only in fir-larch forest.     

Conflict and postconflict behaviour in captive black-and-white snub-nosed monkeys (<Emphasis Type="Italic">Rhinopithecus bieti</Emphasis>)

Black-and-white snub-nosed monkeys (Rhinopithecus bieti) have almost never been the subject of any behavioural observations in captivity. This study was aimed at providing preliminary information about agonistic and reconciliation behaviour in a group kept at the Kunming Institute of Zoology in China. Established procedures were used for this investigation (i.e., the postconflict/matched-control method and the time-rule method). Intra-group aggression rates were quite low. Postconflict affiliation as well as selective attraction of former opponents to each other following conflicts was demonstrated. Former opponents contacted each other earlier in postconflict periods than in matched-control periods. The average conciliatory tendency of all focal individuals combined was 54.5%. After an agonistic interaction, the first affiliative contact between former aggressors usually took place within the first minute. The behaviours most often shown as first affiliations after a conflict were body contact, mount, touch, and hold-lumbar, of which the latter is an explicit reconciliatory gesture. Furthermore, the adult male intervened non-aggressively in 84% of all conflicts (n=25) among the adult females. Overall, the patterns of aggression and reconciliation observed in R. bieti bear many of the traits that characterise tolerant primate species.     

The effect of forest clear-cutting on habitat use in Sichuan snub-nosed monkey (<Emphasis Type="Italic">Rhinopithecus roxellana</Emphasis>) in Shennongjia Nature Reserve,China

The habitat use of two groups of Sichuan snub-nosed monkey (Rhinopithecus roxellana) was observed, using the focal group method, for 7 months in four seasons from June 2000 to October 2001. The habitats were classed into primary forest and three successional habitats: after clear-cutting: grassland, shrub forest and young forest. The results showed that the large group of monkeys had larger range areas than the small group in the same season. Both groups had larger range sizes in summer or autumn than in winter or spring. They spent most of their time using primary forest and young forest, rarely used shrub forest and did not use grassland. In each season, they used the habitats non-randomly and preferred primary forest. The preference order of habitats for both groups every season was the same: primary forest > young forest > shrub forest grassland. The results suggested that primary forest was high-quality habitat and should be conserved as a top priority. Clear-cutting would cause habitat loss and habitat fragmentation, and should therefore be prohibited. High-quality habitat for the monkeys is difficult to restore from clear-cutting.     

Distribution and size of capercaillie leks in relation to old forest fragmentation

Summary Distribution and size of 38 capercaillie Tetrao urogallus leks were related to amount and configuration of old forest patches in two south-east Norwegian coniferous forests. The smallest occupied patch was 48 ha containing a solitary displaying cock. All patches larger than 1 km² contained leks. Number of cocks per lek increased with increasing patch size. Number of leks per patch increased in a step-wise manner with one lek added for each 2.5–3 km² increase in patch size. In large patches there was one lek per 3–5 km² old forest, and density of lekking cocks was 2–2.5 per km². In small patches density of cocks varied considerably. Density of cocks was not related to patch isolation or patch shape. However, among leks surrounded by 50–60% old forest within a 1 km radius, number of cocks increased with increasing old forest fine-graininess. We argue that when old forests cover more than 50%, a fine-grained mosaic may support higher densities of lekking cocks than a coarse-grained mosaic. Conversely, when old forests cover less than 50%, a fine-grained mosaic is unfavourable, because each old forest patch becomes too small and isolated. Finally, we present a predictive model of how old forest fragmentation influences density of leks, number of cocks per lek, and total density of cocks.     

Population Structure and Ranging Patterns of <Emphasis Type="Italic">Rhinopithecus roxellana</Emphasis> in Zhouzhi National Nature Reserve,Shaanxi, China

We describe the population structure and ranging patterns of a troop of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) based on a study conducted between November 2002 and November 2003 in Zhouzhi National Nature Reserve, Shaanxi Province, China. The troop comprised several 1-male units and an all-male unit. Opportunistic censuses revealed that there were ≥112 individuals in the troop. The adult sex ratio (male vs. female) was 1:3.7. The ratios of adults to immatures and infants to adult females were 1:0.7 and 1:2, respectively. Via a grid system, we estimated the home range of the troop to be 18.3 km², of which 7.4 km² was the core area. The subjects exhibited distinct seasonal ranging patterns. Their movement across the home range was extensive in spring and restricted in autumn. In addition, reuse of quadrats was highest in winter and lowest in spring in comparison with other seasons. The daily path length (DPL) varied from .75 to 5 km, with a mean of 2.1 km. Seasonal analysis showed that DPL is significantly shorter in winter than in spring or summer; however, there is no significant difference between the DPLs of spring and summer or those of spring and autumn. The monkeys occupied elevations 1500–2600 m above sea level; the annual mean of altitudinal range is 2137 m. Contrary to early studies that reported Rhinopithecus roxellana migrates to lower elevations in winter, we found no evidence supporting a seasonal altitudinal shift. Using the highest troop count and home range estimate, and considering the extent of range overlap between neighboring troops, we calculated the population density and biomass of Rhinopithecus roxellana to be 7.2 individuals/km² and 68.3 kg/km², respectively. The temporal and spatial distribution of food resources may be the most important determinant of ranging behavior in Rhinopithecus roxellana, though understanding the relationship between resource distribution and seasonal range use may require further investigation.     

Relationship between a high density of sika deer and productivity of the short-grass (<Emphasis Type="Italic">Zoysia japonica</Emphasis>) community: a case study on Kinkazan Island,northern Japan

An extremely high-density (ca. 800 deer km^–2) wild sika deer population uses a short-grass community dominated by Zoysia japonica on Kinkazan Island in northeastern Japan. To explain why the density of wild deer is quite high on the Zoysia community, (1) we quantified the seasonal productivity of the Zoysia community, (2) we compared food availabilities among the plant communities, and (3) we described the habitat selection by the deer in different seasons. Food availability was greater on the Zoysia community than in the forest understory from spring to fall. The productivity of the Zoysia community was high enough to support the actual high density of the deer (814 deer km^–2) in summer. However, the productivity markedly decreased in winter, when the deer density decreased to less than half (358 deer km^–2) of the summer value. In contrast, the deer density of the adjacent forests was highest in winter (154 deer km^–2) and lowest in spring (19 deer km^–2). These results suggest that the deer using the Zoysia community in summer left and were absorbed into the adjacent forest in winter. If such an adjacent community were absent, many deer would not survive, and consequently the deer density on the Zoysia community in summer would not be so high. This intercommunity movement is particularly important for the deer using a plant community like the Zoysia community, which is highly productive but has a small standing biomass.     

Foraging,Food Choice,and Food Processing by Sympatric Ripe-Fruit Specialists: <Emphasis Type="Italic">Lagothrix lagotricha poeppigii</Emphasis> and <Emphasis Type="Italic">Ateles belzebuth belzebuth</Emphasis>

Studies of interspecific competition and niche separation have formed some of the seminal works of ecology. I conducted an 18-mo study comparing the feeding ecologies of 2 sympatric, closely-related ripe-fruit specialists, Humboldt's woolly monkeys (Lagothrix lagotricha poeppigii), and the white-bellied spider monkeys (Ateles belzebuth belzebuth) in Amazonian Ecuador. Woolly monkeys in the terra firme forest live at roughly triple the density of spider monkeys (31 versus 11.5 animals/km²). Woolly monkeys spend 17% of their time foraging, while spider monkeys spend only 1% of their time foraging. Spider monkeys alone fed on soil and termitaria, which are rich in phosphorus. Woolly monkeys are not hard-fruit specialists. Their fruit diet is significantly more diverse than that of spider monkeys. Dietary overlap between the 2 species is high, yet each specializes to some degree on a different set of fruit resources. Woolly monkeys visit more food sources per unit of time, feed lower in the canopy, visit more small food patches, and prey on more seeds. Spider monkeys feed on fewer, richer food sources and are more than twice as likely to return to a particular fruit source than woolly monkeys are. Spider monkeys maximize fruit pulp intake, carrying more intact seeds in their guts, while woolly monkeys minimize seed bulk swallowed through more careful food processing. Surprisingly, several preferred spider monkey foods with high fat content and large seeds are avoided by woolly monkeys. I outline the different ecological dimensions involved in niche separation between the 2 species and discuss the possible impetus for their evolutionary divergence.     

Habitat use of nightjar (Caprimulgus europaeus) in an Austrian pine forest

The Steinfeld in Lower Austria supports a population of European Nightjar (Caprimulgus europaeus) which was extensively studied during 1997 and 1998. The study area encompassed a pine forest of 20 km². The population densities of 1.05 and 1.25 territories/km², respectively, lies within the range found in central European populations. Annual monitoring until 2001 has shown the population to be stable. To gain an insight into habitat use of the species, various habitat-related parameters were measured inside and outside the territories, namely structure of trees, density of trees, structure of undergrowth vegetation and structure of clearings. Discriminant analysis was applied to assess the factors responsible for habitat choice of the Nightjar population. The findings showed that the Nightjars territories were frequently centered on a large clearing with an area of at least 0.7 ha. Clearings less than 50 m wide were not colonized. The requirement for a minimum width of a clearing in addition to a minimum area probably relates to better hunting conditions. Nightjars prefer trees where the lower edge of the crown is on average 4.38 m higher than at control points so that males can churr from dead branches immediately below the canopy. Such trees were found on the edge of clearings in the forest, and the edge of a clearing thus had a pronounced effect on the quality of a territory. In contrast to reports in the literature, neither the proportion of bare patches of ground nor the average height of undergrowth vegetation was found to be decisive for territory selection.