Activity and Ranging Patterns of <Emphasis Type="Italic">Colobus angolensis ruwenzorii</Emphasis> in Nyungwe Forest,Rwanda: Possible Costs of Large Group Size

With group sizes sometimes >300 individuals, the Angolan black-and-white colobus (Colobus angolensis ruwenzorii) population in Nyungwe Forest, Rwanda is an intriguing exception to the tendency for folivores to live in smaller groups than expected relative to body size. Researchers have hypothesized that the unusually high quality of foliage at Nyungwe allows colobus there to avoid intragroup feeding competition, releasing constraints on the formation of large groups (Fimbel et al., 2001). We collected data on the activity and ranging patterns of a >300-member Nyungwe colobus group and compared our results to those from smaller groups in other black-and-white colobus (Colobus spp.) populations. Colobus at Nyungwe spent far more time feeding and moving (62%) and far less time resting (32%) than black-and-white colobus at any other site. The annual home range of the Nyungwe colobus was also many times larger (95% minimum convex polygon: 20.7 km ² ; 95% fixed kernel: 24.4 km ² ) than those for other populations. We terminated our research after the group engaged in an unprecedented migration among black-and-white colobus by moving 13 km south of their former range. Our results suggest that intragroup scramble competition may be more intense than originally believed within the large colobus groups at Nyungwe and that long periods of resource renewal may be necessary after a large colobus group passes through an area, thereby potentially helping to explain their wide ranging patterns. We discuss the socioecological convergence between the Nyungwe colobus and Chinese snub-nosed monkeys (Rhinopithecus spp.) and suggest directions for future research on the unique black-and-white colobus population at Nyungwe.

Group size in folivorous primates: ecological constraints and the possible influence of social factors

The ecological-constraints model assumes that food items occur in depletable patches and proposes that an increase in group size leads to increased day range due to more rapid patch depletion. Smaller groups become advantageous when an increase in travel costs is not repaid by an increase in energy gained or some other fitness advantage. On the other hand, we also know that group size can be influenced by social factors. Here we contrast the diet and group size of red colobus (Procolobus badius) and black-and-white colobus (Colobus guereza) in Kibale National Park, Uganda to consider how ecological and social factors are affecting their group sizes. Subsequently, we examine whether the insights gained from this detailed comparison can provide an understanding of why the social organization and group size of mantled howlers (Alouatta palliata) and black howlers (A. pigra) differ. Two groups of red colobus and two groups of black-and-white colobus were studied over 10 months. Red colobus groups were larger (48 and 24) than black-and-white colobus groups (9 and 6). The two groups of red colobus overlap home ranges with the two groups of black-and-white colobus; 75% and 95% of their home ranges were within red colobuss home range. There was a great deal of similarity in the plant parts eaten by the two species and both species fed primarily on young leaves (red colobus 70%, black-and-white colobus 76%). In terms of the actual species consumed, again there was a great deal of similarity between species. The average dietary overlap among months for the two neighboring groups of red colobus was 37.3%, while the dietary overlap between the red colobus and the black-and-white colobus group that had its home range almost entirely within the home range of the red colobus groups averaged 43.2% among months. If ecological conditions were responsible for the difference in group size between the two colobine species, one would expect the density of food trees to be lower in the home ranges of the black-and-white colobus monkeys, since they have the smaller group size. We found the opposite to be true. Both black-and-white colobus groups had more food trees and the cumulative size of those trees was greater than those in the red colobuss home ranges. We quantify how these differences parallel differences in mantled and black howlers. The average group size for mantled howlers was 12.9 individuals, and for black howlers it was 5.3 individuals. We explore possible social constraints, such as infanticide, that prevent black-and-white colobus and black howlers from living in large groups.This revised version was published online in April 2005 with corrections to the cover date of the issue.     

Implications of small scale variation in ecological conditions for the diet and density of red colobus monkeys

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.     

Spacing behaviour and habitat use of rock ptarmigan (Lagopus mutus) at low density in the Italian Alps

Studies of rock ptarmigan Lagopus mutus in northern latitudes have shown that, in the breeding season, the majority of cocks pair monogamously and defend small territories, whilst in most populations, a small proportion of cocks are polygynous or remain unmated. Little is known, however, on spacing behaviour and habitat use of alpine rock ptarmigan populations occurring at low densities at the southern edge of the species’ range. From 1995 to 1997, we trapped, radio-tracked and observed birds in the Central Italian Alps (elevation 2,000–3,000 m) in order to investigate spacing behaviour and habitat use in alpine landscapes where habitats offering rich food and cover are patchy. Both sexes were selective in their habitat use, and cocks did not establish territories on bare ground, artificial or nutrient rich grasslands or bogs. In the breeding season, cocks had larger home ranges than hens (cocks 99 ± 57 ha, hens 50 ± 25 ha) that overlapped with the ranges of neighbouring cocks and hens. Cocks were monogamous and defended relatively large territories (core areas of home ranges: cocks 37 ± 26 ha, hens 24 ± 12 ha), which corresponded with low spring densities (0.47–2.29 cocks km⁻² and 0.35–1.60 pairs km⁻²). Territory size of individual cocks was negatively correlated with the amount of high quality habitat in the core-area. Our results suggest increased home ranges and large breeding territories in low density alpine rock ptarmigan populations, compared to populations occurring at higher densities in the central and northern alps, and on subarctic and arctic grounds at northern latitudes, confirming the predictions of models on food-based territoriality.     

北京地区红隼的迁徙路线和活动区域

红隼(Falco tinnunculus)被列为国家二级重点保护野生动物,是能同时适应农村和城市环境的小型猛禽,对维持城市生态系统稳定具有重要意义。2022年4月至7月,为在北京救助的7只红隼佩戴了卫星追踪器,追踪其活动轨迹,依据追踪的动物活动位点数据,采用净平方位移-时间曲线依次对各红隼的迁徙模式进行了判别,深入分析了迁徙红隼的迁徙时间、距离和路线等,并采用核心密度法分别计算了迁徙及留居型红隼95%及50%活动区面积。研究结果表明,在北京地区红隼的迁徙模式为部分迁徙,追踪的7只红隼个体(N01 ~ N07)中,4只为留鸟,1只为迁徙鸟,2只居留类型无法准确判断。N01为迁徙红隼,其度夏地和越冬地分别在内蒙古锡林郭勒盟和河北廊坊,此红隼秋季迁徙速度明显高于春季,其春季迁徙距离551 km,历时25 d,平均迁徙速度为22 km/d,而秋季迁徙距离412 km,历时2 d,平均迁徙速度为203 km/d,河北承德滦平县是其春季迁徙的重要中途停歇地。不同红隼个体间95%及50%活动区面积均存在较大差异,迁徙红隼N01 95%、50%活动区面积在度夏区分别为93.10 km²、17.50 km²,在越冬区分别为7.03 km²、0.99 km²;留居型红隼95%、50%活动区面积均值分别为1 165.34 km²、178.71 km²(n = 4),其中最大95%、50%活动区面积分别为4 320.26 km²(N02)、648.22 km²(N02),最小95%、50%活动区面积分别为2.80 km²(N03)、0.29 km²(N03)。本研究揭示了北京地区红隼的迁徙模式、迁徙路线、重要停歇地及活动区状况,为红隼的针对性保护和管理提供了科学依据。     

Seasonal migration patterns of female sika deer in eastern Hokkaido,Japan

Fifty-seven female sika deer (Cervus nippon yesoensis), captured at the wintering area in the Shiranuka Hills in eastern Hokkaido, Japan, were radio-tracked during 1997–2001 to examine the factors affecting seasonal migration at the individual-landscape level. Ten of the 57 deers migrated between low-altitude summer home ranges and intermediate-altitude winter home ranges (the upward migrants). Twenty-nine migrated between high-altitude summer home ranges and intermediate-altitude winter home ranges (the downward migrants). Twelve used the intermediate-altitude home ranges all year round (the non-migrants). The remaining six were unknown. The summer home ranges of deer were widely scattered over an area of 5734km². Migration distances ranged between 7.2 and 101.7km. Deer showed high site fidelities to their seasonal home ranges. The upward migrants wintered in areas of less snow, higher quality of bamboo grass, and more coniferous cover than their summer home ranges. The downward migrants wintered in areas of less snow, higher quality of bamboo grass, higher winter temperature, and more southern slopes, but less coniferous cover than their summer home ranges. The non-migrants used year-round ranges with little snow, high quality of bamboo grass, and sufficient coniferous cover. We suggest that snow cover and bamboo grass are the factors affecting seasonal migration of the population and that coniferous cover is another factor for the upward migration.     

Rates of predation on mammals by gombe chimpanzees, 1972–1975

Rates of chimpanzee predation on mammals are calculated using data on 75 kills recorded during focal observation in Gombe National Park, Tanzania, from January 1972 to April 1975. The chimpanzees were members of two study communities (Kanyawara, or Northern, and Kahama, or Southern, community), and were observed as focal individuals for 14,583 hr by more than 30 researchers and field assistants working in pairs. The rate of predation by females was too low to allow reasonable estimates. For males, the mean rate of killing during the study period was 0.31 kills per male per 100 hr (N=17 males), or 4.65 kills per 100 hr in the two communities. In contrast to results from Mahale Mountains, there was no difference in predation rate between wet and dry seasons. However, predation rates varied over time, increasing by four times between the first three and last four seasons of the sample period. In an average year the 15 adult and subadult male chimpanzees are calculated to have killed 204 prey per year in an area of 16 km², varying between 99 and 420 prey per year in periods of low and high predation rate. Red colobus were the most frequent prey, followed by bushpig and bushbuck. Predation rates varied greatly on different prey species, and were not related to either the proportion of time spent within 200 m of male chimpanzees, or to their population densities. In relation to encounter rates and population density, baboons, blue monkeys, and redtail monkeys were killed at a fraction of the rate of red colobus monkeys, which suffered severe mortality from chimpanzee predation. Predation on bushpig and bushbuck also appears to have been high in relation to population density. The amount of food provided by predation is estimated to have averaged 600 kg per year for chimpanzees in the two communities (totalling 14–17 adult or subadult males, 18–20 adult of subadult females, and about 19 infants or juveniles). This suggests that adult males consumed around 25 kg of meat per year, although any average figure undoubtedly masks considerable individual variation. Present data suggest that chimpanzees in Gombe and Tai National Park, Ivory Coast, prey on mammals at rates higher than other populations.     

Population Sizes and Distribution of Primates in the Lower Tana River Forests,Kenya

We studied the population size and distribution of diurnal primates in the lower Tana River forests, Kenya. They are the only remaining habitats for 2 threatened primates: the Tana River red colobus (Procolobus rufomitratus) and the Tana River crested mangabey (Cercocebus galeritus galeritus). We conducted censuses in 73 forest patches from January through March 2001. We estimate population size of the red colobus to be 788 individuals in 82 groups and that of the crested mangabeys to be 2,070 individuals in 59 groups. The data suggest that over a 7-year period (1994-2001), there was an 18% increase in the crested mangabey population and a 5% decline in red colobus numbers. Further, the red colobus range has expanded both north and south, whereas that of crested mangabeys has only expanded south. Fifty-six percent of crested mangabeys and 46% of red colobus groups were inside the Tana River Primate National Reserve (TRPNR). Other primates encountered included 170 groups of Sykes' monkeys (Cercopithecus mitis), 70 groups of yellow baboons (Papio cynocephalus) and 4 groups of grivets [Chlorocebus (Cercopithecus) aethiops]. Mean group densities of the 2 endangered primates and of baboons were higher inside than outside the TRPNR, reinforcing the importance of TRPNR for their conservation. An intervention program is required to stem further decline in the red colobus population and to protect small isolated groups in forest patches outside TRPNR.     

Distribution,Population Structure and Habitat Use of Microcebus berthae Compared to Those of Other Sympatric Cheirogalids

We aimed to identify the geographical and biotic limitations of Microcebus berthae, the smallest extant primate. Furthermore we analyzed the mating system of two local populations and their habitat use in relation to microhabitat structures and to those of Microcebus murinus and Cheirogaleus medius, two potentially competing lemur species. The range of Microcebus berthae is restricted to 220 km² in the dry deciduous forest of western Madagascar. A very optimistic estimate of the total population size is ca. 7900 individuals. During a 13-mo mark-recapture study individuals were trapped from May 1995 to May 1996 at permanent trap locations 50 m apart over 2 study areas of ca. 25 ha each. The spacing of trap locations where individuals have been retrapped indicate that males have larger home ranges than those of females, which in concert with multiple intra- and intersexual range overlap indicates a promiscuous mating system. In contrast to the other 2 species, Microcebus berthae maintained specific habitat utilization patterns at 2 sites with different vegetation structures. Their habitat use in relation to vegetation characteristics differed from that of Cheirogaleus medius but not from that of Microcebus murinus. Co-occurrence patterns of Microcebus berthae and M. murinus deviated significantly from random and resembled a checkerboard distribution possibly generated by competitive exclusion. Thus, according to the niche concept, Microcebus berthae seem to be separated from Cheirogaleus medius by differences in food composition and habitat requirements, while they avoid direct competition with M. murinus by spatial separation.     

Effect of Group Size on Activity Budgets of Colobus vellerosus in Ghana

Group size influences foraging efficiency in several primates. We examined the activity budgets of 3 groups of Geoffroy's pied colobus (Colobus vellerosus) at the Boabeng-Fiema Monkey Sanctuary in Ghana to determine whether larger group size induces scramble competition. We studied 2 groups (B1; N = 7-8 and WW; N = 31-33) occupying slightly overlapping home ranges from August to November 2000. We observed the third group, B2 (N = 15-16), comprising B1 and 7 male invaders in the same home range as B1 from August to November 2001. By comparing groups belonging to the same population and occupying sligthly overlapping or similar home ranges, we were able to control, to a certain extent, for differences in food distribution. We recorded a total of 3353 scans, yielding 14,886 activity records, over 73 days. As with other black-and-white colobus, resting was their most common activity (59%). Intergroup comparisons suggest that time spent feeding, resting and moving did not vary in relation to group size. However, intragroup comparisons between the sexes show that females in the large group spent more time feeding than males did, whereas this was not the case in the small group, which suggests that scramble competition may be occurring among female Colobus vellerosus at BFMS. It is also possible that this may be due to greater nutritional requirements because of a higher proportion of infants in the large group. In fact, the proportion is quite similar between the two groups, lending support to the idea that females in the two groups had comparable nutritional demands due to lactation. This suggests that increased feeding in females in the large group was partly an effect of scramble competition. Group size and group composition also influenced the frequency of social behavior. There was more grooming in the large group, and it was performed mostly by females. The distribution of activities throughout the day was similar to the pattern reported for other black-and-white colobus.     

Charcoal Consumption by Zanzibar Red Colobus Monkeys: Its Function and Its Ecological and Demographic Consequences

The Zanzibar red colobus monkey is the only primate, aside from humans, known to eat charcoal in the wild. All age classes and both sexes eat charcoal, but only those groups living in perennial gardens or near human dwellings do so. The habit appears to be transmitted from mother to offspring by imitation, but how it developed in the first place is unknown. Sources of charcoal include charred stumps, logs, and branches, as well as that produced in kilns by humans. These charcoals adsorb organic materials, such as phenolics, particularly well and, as a consequence, remove these compounds, which have the potential to be toxic or interfere with digestion or both. The extreme inertness of charcoal makes it an unlikely source of minerals to the colobus. We conclude that, by eating charcoal, monkeys living in gardens with a high density of food species dominated by exotic trees — Indian almond and mango — are able to exploit this abundant food resource that is high in total phenolic content much more effectively than in the absence of charcoal. The young leaves of these exotic tree species are also very high in protein and highly digestible. The benefits of charcoal eating are most likely due to the fact that charcoal adsorbs phenolics better than proteins. This may explain in large part why the birth rates and population densities of the colobus living in the Indian almond and mango habitat adjacent to the Jozani Forest are significantly higher than those in the ground-water forest. The population density of colobus in this small area is the highest ever recorded for a nonhuman anthropoid (700/km ² ). It may not, however, be a stable situation, as there are indications of higher levels of aggression, lower recruitment into the medium-juvenile size class, and overbrowsing.     

Nitrogen fixation in perennial forage legumes in the field

Nitrogen acquisition is one of the most important factors for plant production, and N contribution from biological N₂ fixation can reduce the need for industrial N fertilizers. Perennial forages are widespread in temperate and boreal areas, where much of the agriculture is based on livestock production. Due to the symbiosis with N₂-fixing rhizobia, perennial forage legumes have great potential to increase sustainability in such grassland farming systems. The present work is a summary of a large number of studies investigating N₂ fixation in three perennial forage legumes primarily relating to ungrazed northern temperate/boreal areas. Reported rates of N₂ fixation in above-ground plant tissues were in the range of up to 373 kg N ha^–1 year^–1 in red clover (Trifolium pratense L.), 545 kg N ha^–1 year^–1 in white clover (T. repens L.) and 350 kg N ha^–1 year^–1 in alfalfa (Medicago sativa L.). When grown in mixtures with grasses, these species took a large fraction of their nitrogen from N₂ fixation (average around 80%), regardless of management, dry matter yield and location. There was a large variation in N₂ fixation data and part of this variation was ascribed to differences in plant production between years. Studies with experiments at more than one site showed that also geographic location was an important source of variation. On the other hand, when all data were plotted against latitude, there was no simple correlation. Climatic conditions seem therefore to give as high N₂ fixation per ha and year in northern areas (around 60°N) as in areas with a milder climate (around 40°N). Analyzing whole plants or just above-ground plant parts influenced the estimate of N₂ fixation, and most reported values were underestimated since roots were not included. Despite large differences in environmental conditions, such as N fertilization and geographic location, N₂ fixation (Nfix; kg N per ha and year) was significantly (P<0.001) correlated to legume dry matter yield (DM; kg per ha and year). Very rough, but nevertheless valuable estimations of Nfix in legume/grass mixtures (roots not considered) are given by Nfix = 0.026DM + 7 for T. pratense, Nfix = 0.031DM + 24 for T. repens, and Nfix = 0.021DM + 17 for M. sativa.     

Population Density and Home Range Size of <Emphasis Type="Italic">Indri indri</Emphasis> in a Protected Low Altitude Rain Forest

We report the results of a census of Indri indri conducted in Betampona Nature Reserve, a lowland rain forest in eastern Madagascar. In addition, we conducted a year-long study of the ranging behavior of 3 groups in the southwestern region of the reserve. We used 2 methods to calculate population density and home range size, and to provide minimum and maximum estimates. Population density of Indri indri ranged from 6.9–13.2 individuals/km² in Betampona. Mean home range size is 27 ha. The values for population density and home range size are intermediate between values for Indri indri in selectively logged and undisturbed montane rain forest. Our results suggest a relationship between habitat disturbance, population density and home range size for the species. Recent increases in habitat disturbance appear to cause an increase in population density and a decrease in home range size. The results are consistent with ones for other folivorous primate populations. Further research on habitat requirements of Indri and availability in Betampona is necessary to investigate the possibility of translocating Indri from nearby forest fragments into Betampona.     

Home range and habitat use by the sable<Emphasis Type="Italic"> Martes zibellina brachyura</Emphasis> in a Japanese cool-temperate mixed forest

Home range and habitat use of the sable Martes zibellina brachyura were studied in a cool-temperate mixed forest in northernmost Japan. In both sexes, some sables showed a wide range of migration without establishing home ranges and the others had home ranges of 0.50–1.78 km² (mean: 1.12±SD 0.495 km², n =6) which were not significantly correlated with body weight or age. The analysis of canine tooth annuli revealed that the maximum age was 5.5 years. The home ranges of some sables overlapped so extensively that the home ranges and even the core areas did not appear exclusive to other sables. We determined resting sites and foraging routes in snow in winter. Comparison of vegetation at the resting sites and foraging routes with habitat availability suggested that the sables preferred resting in dense-tree forests with many tree species and debris probably in order to avoid predators (red foxes) and strong wind and foraging in forests of climax succession which are usually rich in their prey such as voles and mice.     

Camera-trap studies of maned wolf density in the Cerrado and the Pantanal of Brazil

The maned wolf (Chrysocyon brachyurus) is threatened by large-scale habitat loss, in particular due to conversion to agricultural land. This is the first published study on maned wolf density and the first test of individual identification from camera-trap photographs. We present results from two Brazilian regions: the Cerrado and the Pantanal. Using capture–recapture analysis of camera-trap data, we estimated densities per 100 square kilometers of 3.64 ± 0.77 individuals at the Cerrado site and 1.56 ± 0.77 individuals at the Pantanal site. Parallel radio-telemetry studies at the Pantanal site showed that maned wolves occupied home ranges of 39–58 km² (mean = 50.3 ± 7.67 km²). Our study in the Cerrado took place in a private farm with a mixture of agricultural land and native habitats, representative of the majority of the present-day Cerrado. Whereas many other mammalian species have suffered in the region, our results show that the maned wolf may cope better with this highly fragmented landscape than one might have feared. Finally, the paper briefly compares maned wolf density with density of puma (Puma concolor) in the Pantanal site.     

Ecology of the Zanzibar Red Colobus Monkey: Demographic Variability and Habitat Stability

We examined the Zanzibar red colobus' (Procolobus kirkii) social structure and population dynamics in relation to the density, diversity and dispersion of food resources in ground-water forest and agricultural land, which we characterized in terms of red colobus food species density, diversity, basal area and dispersion. We used transect sampling and group follows to describe population dynamics and social systems. Two agricultural areas, SJF Shamba and Pete Village, had higher densities and more uniformly dispersed red colobus food tree species than those of the ground-water forest. Red colobus at these two sites had greater population densities and natality, and smaller home ranges than red colobus in the ground-water forest. However, these findings apply to a very small area of agricultural land (approximately 18 ha) that is contiguous with an area of the forest reserve having a high density of red colobus. It is not representative of agricultural areas elsewhere on Zanzibar which support much lower densities or no red colobus. Although agricultural areas contiguous with the forest reserve had high densities of red colobus, they appear to be very unstable. Within the agricultural areas, we observed higher intergroup variation in group size and composition, study groups that decreased dramatically in size and disappeared from the study site, significantly lower levels of juvenile recruitment, and red colobus food trees that exhibited definite signs of overbrowsing. This apparent instability in the subpopulation of red colobus utilizing agricultural systems probably reflects the lower basal area of food trees and the greater fragmentation of suitable habitat and floristic dynamics due to human activities in these areas. A fusion-fission social system occurred only in the ground-water forest subpopulation, which we hypothesize to be due to highly clumped food resources.     

Census and distribution of chimpanzees in Côte D’Ivoire

Most methods of estimating chimpanzee population densities rely on nest counts. We tested the most frequently used techniques on a known chimpanzee community living in the rainforest of the Taï National Park, Côte d’Ivoire. The best density estimates are given by counts that assume groups of nests to be distributed randomly and that use the mean group size for homogenous habitat but the median for heterogenous habitats. Correction for real forest cover within the region should be made because chimpanzees make nests only in forested regions. This method gave the exact chimpanzee density for the Taï population, i.e. 1.7 nest builders/km². For the nationwide survey, we first estimated the chimpanzee density for different types of habitat (e.g. intact primary forest: 1.64 chimpanzees/km²; degraded forests: 0.4 chimpanzees/km²; human encroached forests and mosaic habitats: 0.09 chimpanzees/km²). Second, we estimated the total forest cover of the country with satellite pictures. This gave an estimated chimpanzee population in Côte d’Ivoire of about 11,676 ± 1,168 individuals, which equals the number of spectators at a soccer game in an average European town. Sadly, only three National Parks may have chimpanzee populations large enough to be viable, whereas the rest are scattered and isolated small populations that are already threatened in their survival.     

Effect of application rates and abiotic factors on Steinernema carpocapsae for control of overwintering navel orangeworm (Lepidoptera: Pyralidae, Amyelois transitella) in pistachios

The effect of reduced application rate, soil temperature at shallow depth (2.5 cm), and soil type on the efficacy of Steinernema carpocapsae against the navel orangeworm, Amyelois transitella, was evaluated in six field trials employing 1 m² plots conducted from November 2003 through December 2004 in Madera and Kern Counties, California. Nematodes were applied at a concentration of 100,000 infective juveniles (IJs)/m² (10⁹/ha) in a volume of 187 ml water/m² (1870 L/ha) with a post-application irrigation in all trials. Mortality ranged from 7.9 to 64.9% in successful trials and percent reduction in live larvae per plot was as high as 74.6%. Percent reduction and mortality were highly correlated (r² = 0.78) and larval reduction typically was 10–11% greater than mortality for any treatment. In one trial, although nematode treatment significantly increased mortality compared to the controls, the treatment was deemed unsatisfactory because mortality was <15%. Soil temperature in this trial rose to 39 °C within 5 h after application. Nematodes failed in two other trials when soil temperature fell below freezing (minimum temperatures −3.0, −5.5 °C, respectively) several times in a 5-day period. We conclude that a commercially feasible application volume of 1870 L water/ha followed by post-application irrigation at this same rate was effective, and that soil maximum temperature at or below 32 °C during the first 24 h after application is necessary for treatment success.     

Habitat Degradation of Rhinopithecus bieti in Yunnan, China

Black-and-white snub-nosed monkeys (Rhinopithecus bieti) are endemic to the Trans-Himalayas in Northwest Yunnan and Southeast Tibet between the upper Yangtze and Mekong Rivers. Based on field surveys and previous reports, we identified the dark-coniferous forest, the mixed coniferous and broadleaf forest, and oak patches as suitable habitats (SH) for the monkeys. Summer grazing lands (SGL), which were made by local people cutting and burning the dark-coniferous forest at the high altitude belt, replaced SH. To have a general view of the status of the SH in Yunnan, we estimated the areas of SH and SGL from satellite images in 1997, and compared with areas estimated from aerial photo-based maps (ca. 1958). The work resulted in: 1) the area of SH was 4,169 km² in 1997; 2) SGL was 1,923 km²; 3) during the past 40 years, the area of SH decreased by 31% (1,887 km²), and SGL increased by 204% (1,291 km²); and 4) the mean size of forest patches decreased from 15.6 to 5.4 km². In addition, the area of SGL is positively correlated to local human population (R² 0.53), implying that the reduction and fragmentation of habitat for Rhinopithecus bieti is a result of population growth of humans, who mostly employ traditional modes of production. Only 11 monkey groups remained in the changing habitat. Considering that forests at lower elevation were also encroached upon by farmlands in a similar way, the forest ecosystem is highly threatened. The destruction will continue unless there is a change in the mode of production in the region.     

Home Range and Frugivory Patterns of Mountain Gorillas in Bwindi Impenetrable National Park,Uganda

Mountain, western, and Grauer's gorillas exhibit broad differences in ecological patterns with western gorillas eating more fruit and having larger home ranges than their largely folivorous counterparts in the Virunga Volcanoes. We studied the home range and frugivory patterns of one group of Gorilla beringei beringei in the little-studied population of Bwindi Impenetrable National Park, Uganda, to compare with other populations and to investigate whether there was any relationship between patterns of frugivory and home range size. During the 3-year study, the gorillas ate 16 species of fruit on 27% of observation days. There was high variability in frugivory among the 3 years and no consistent seasonal pattern. Annual home range size was ca. 21 km² for Years 1 and 2, and it increased dramatically to 40 km² in Year 3. Home range size varied considerable between months and seasons, but there is no clear relationship between occurrence of fruit-eating and home range size. The group exhibited more fruit-eating and a larger home range size those ofthe gorillas in the Virunga Volcanoes. Their home range size is comparable to that of western gorillas, though Bwindi gorillas consumed less fruit. Home range size and utilization by all gorillas probably depends on a complex relationship between the distribution and abundance of both fruit and herbaceous vegetation and social factors such as male mating tactics.