Vegetation correlates of gibbon density in the peat‐swamp forest of the Sabangau catchment,Central Kalimantan,Indonesia

Understanding the complex relationship between primates and their habitats is essential for effective conservation plans. Peat‐swamp forest has recently been recognized as an important habitat for the Southern Bornean gibbon (Hylobates albibarbis), but information is scarce on the factors that link gibbon density to characteristics of this unique ecosystem. Our aims in this study were firstly to estimate gibbon density in different forest subtypes in a newly protected, secondary peat‐swamp forest in the Sabangau Catchment, Indonesia, and secondly to identify which vegetation characteristics correlate with gibbon density. Data collection was conducted in a 37.1 km² area, using auditory sampling methods and vegetation “speed plotting”. Gibbon densities varied between survey sites from 1.39 to 3.92 groups/km². Canopy cover, tree height, density of large trees and food availability were significantly correlated with gibbon density, identifying the preservation of tall trees and good canopy cover as a conservation priority for the gibbon population in the Sabangau forest. This survey indicates that selective logging, which specifically targets large trees and disrupts canopy cover, is likely to have adverse effects on gibbon populations in peat‐swamp forests, and calls for greater protection of these little studied ecosystems. Am. J. Primatol. 72:607–616, 2010. © 2010 Wiley‐Liss, Inc.     

Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia

We demonstrate that although auditory sampling is a useful tool, this method alone will not provide a truly accurate indication of population size, density and distribution of gibbons in an area. If auditory sampling alone is employed, we show that data collection must take place over a sufficient period to account for variation in calling patterns across seasons. The population of Hylobates albibarbis in the Sabangau catchment, Central Kalimantan, Indonesia, was surveyed from July to December 2005 using methods established previously. In addition, auditory sampling was complemented by detailed behavioural data on six habituated groups within the study area. Here we compare results from this study to those of a 1-month study conducted in 2004. The total population of the Sabangau catchment is estimated to be about in the tens of thousands, though numbers, distribution and density for the different forest subtypes vary considerably. We propose that future density surveys of gibbons must include data from all forest subtypes where gibbons are found and that extrapolating from one forest subtype is likely to yield inaccurate density and population estimates. We also propose that auditory census be carried out by using at least three listening posts (LP) in order to increase the area sampled and the chances of hearing groups. Our results suggest that the Sabangau catchment contains one of the largest remaining contiguous populations of Bornean agile gibbon.     

Comparison of point transect distance and traditional acoustic point-count sampling of hoolock gibbons in Htamanthi Wildlife Sanctuary,Myanmar

Effective conservation demands more accurate and reliable methods of survey and monitoring of populations. Surveys of gibbon populations have relied mostly on mapping of groups in “listening areas” using acoustical point-count data. Traditional methods of estimating density in have usually used counts of gibbon groups within fixed-radius areas or areas bounded by terrain barriers to sound transmission, and have not accounted for possible decline in detectability with distance. In this study we sampled the eastern hoolock gibbon (Hoolock leucogenys) population in Htamanthi Wildlife Sanctuary (WS), Myanmar, using two methods: the traditional point-count method with fixed-radius listening areas, and a newer method using point-transect Distance analysis from a sample point established in the center of each listening point array. The basic data were obtained by triangulating on singing groups from four LPs for 4 days, in 10 randomly selected sample areas within the sanctuary. The point transect method gave an average density of 3.13 groups km⁻², higher than the estimates of group density within fixed-radius areas without correction for detectability. A new method of analysis of singing probability per day (p[1]) gave an estimate of 0.547. Htamanthi WS is an important conservation area containing an estimated 7000 (95% confidence interval: 5000–10,000) hoolock groups. Surveys at Htamanthi WS and locations in the Hukaung Valley suggest that the extensive evergreen forests in northern Myanmar have the capacity to support 2–4 (average about 3) groups of hoolock gibbons per km², but most forests in its range have yet to be surveyed.     

Population densities of Sulawesi crested black macaques (Macaca nigra) on Bacan and Sulawesi,Indonesia: Effects of habitat disturbance and hunting

Population surveys of Sulawesi crested black macaques (Macaca nigra) were conducted on the Indonesian islands of Sulawesi and Bacan in 1992–1994 to assess the status of natural populations and determine habitat and anthropogenic factors affecting their population densities. We surveyed five sites for primates, including undisturbed and disturbed habitats. Data were collected on habitat structure and composition at two undisturbed and one disturbed forest site in which the primates were surveyed. The highest density of macaques was found in primary forest at Gunung Sibela Nature Reserve on Bacan (170.3 individuals/km²). Population density in logged forest on Bacan was high but significantly less than primary forest (133.4 individuals/km²). The high density of crested black macaques in primary forest on Bacan is best explained by the high carrying capacity found in primary forest. The lower food quantity and quality of food resources found in logged forest correlated with lower primate densities compared to primary forest. However, the large population of macaques in logged forest demonstrates the conservation value of such forest. Densities on Sulawesi at Tangkoko-Batuangas-DuaSudara Nature Reserve (TBDS) showed a continuing decline since earlier surveys. Primate densities were highest near the protected center of Tangkoko Reserve (66.7 individuals/km²). The peripheral areas of Batuangas and DuaSudara, even though adjacent and continuous, showed lower population densities of 46.4 and 23.5 individuals/km², respectively. The best explanation for the continued decline of Macaca nigra populations at TBDS is hunting. Unless conservation measures are implemented immediately, M. nigra on Sulawesi risks extinction in the near future. Am. J. Primatol. 44:89–106, 1998. © 1998 Wiley-Liss, Inc.     

Combining species distribution modeling and distance sampling to assess wildlife population size: A case study with the northern yellow-cheeked gibbon (Nomascus annamensis)

Population size and distribution data for wildlife species play an important role in conservation and management, especially for endangered species. However, scientists seriously lack data on the population status of many species. The northern yellow-cheeked gibbon (Nomascus annamensis) is found in southern Lao PDR, central Vietnam, and northeastern Cambodia. The population of the species has significantly declined due to hunting, habitat loss, and the wildlife trade. To examine the population size and distribution of N. annamensis, we conducted a field survey in Song Thanh Nature Reserve, Quang Nam Province, central Vietnam from February to April 2019 using the audio point count method. We combined Distance Sampling and Ecological Niche Modeling to estimate the population of the gibbons. Results showed that the total suitable area for the gibbons was about 302.32 km², with the two most important variables of the habitat model being the distance-to-villages and forest type. We detected 36 gibbon groups through field surveys and estimated 443 (95% CI, 278–707) gibbon groups in Song Thanh Nature Reserve. Our results indicate that the gibbon population in Song Thanh Nature Reserve is the largest known population of N. annamensis in Vietnam. In addition, our study was the first to combine species distribution modeling with distance sampling to estimate gibbon density and population size. This approach might be useful in surveying and monitoring gibbon populations because it takes imperfect detection probability into account in estimating gibbon population density while estimating the area of potential habitat using environmental variables.     

Wattled Curassows in Bolivia: abundance,habitat use,and conservation status

ABSTRACT The Wattled Curassow (Crax globulosa) is a globally threatened species restricted to humid várzea forest (seasonally flooded forest along white‐water rivers) in low‐lying regions of Amazonia. The Wattled Curassow were thought to have been extirpated from the Beni area of Bolivia, but were rediscovered near the Río Negro River in 2001. Our objectives were to determine the size of this population, examine habitat use, and based on our results, assess the conservation status of the Wattled Curassow. During July and August 2006, we used distance sampling to estimate the population density in our study area. We estimated the density of Wattled Curassows at 3.4 (95% CI: 1.4–8.1) individuals/km² and all were observed within 300 m of the river. Based on the availability of suitable habitat (18 km² of riparian várzea habitat within 300 m of the river), we estimated that the breeding population of Wattled Curassows in our study area consisted of 61 individuals. The specialized habitat requirements of the Wattled Curassow has important conservation implications because previous population estimates were based on the availability of várzea forest rather than the availability of water edge habitat within várzea forest. As a result, the current global population estimate (2500–9999) is higher than our estimate (500–2500) that takes the specialized habitat requirements of the Wattled Curassow into account. Given this low estimated population, along with the severely fragmented state of the few remaining populations and their dependence on a specialized and vulnerable habitat, we recommend that the status of the Wattled Curassow be upgraded from Vulnerable to Endangered.     

Habitat use,density, and conservation status of the white-browed guan (Penelope jacucaca Spix, 1825)

The white-browed guan (Cracidae: Penelope jacucaca) is an endemic bird species to the Caatinga, the largest centre of dry forest in South America. This taxon was considered Vulnerable by the International Union for Conservation of Nature (IUCN) due to continued habitat loss within its distribution and intense hunting pressure that contributed to population declines. However, information on population aspects and habitat use by P. jacucaca, which is fundamental for monitoring its conservation status, is not available. We studied habitat use (analysed in a Generalized Linear Model) and population density (estimated by distance sampling) in a specific area in Northeast Brazil. Using species distribution modelling (SDM), forest cover loss data (performed in the MaxEnt program) and quantitative information about hunting, more rigorous estimates of the distribution limits, available habitat, and population declines of P. jacucaca were generated. Based on the IUCN criteria, we applied analysed data to reassess the conservation status of the white-browed guan. Local density was estimated at 13.1 individuals/km² and the estimated number of individuals removed per year due to hunting was 121.7 in the forest cover area (110.46 km²) of the Serra de Santa Catarina. Consequently, the annual removal rate of hunted individuals in the study area corresponds to approximately 11% of the population. The habitat use analysis pointed to a strong positive association with seasonally dry deciduous forest (SDDF) vegetation and with arboreal vegetation. The SDM indicated a potential distribution (climatically favourable) area of 675,823 km², and forest cover and loss calculations indicated a total of 81,307 km² of available suitable habitat in 2013. Therefore, comparing these results to the IUCN criteria, we recommend that P. jacucaca remain in the Vulnerable category.     

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.     

Focusing Conservation Efforts for the Critically Endangered Brown-headed Spider Monkey (<Emphasis Type="Italic">Ateles fusciceps</Emphasis>) Using Remote Sensing,Modeling, and Playback Survey Methods

Brown-headed spider monkeys (Ateles fusciceps), endemic to the Choco-Darien forests and lower Andean forests of NW Ecuador, are considered critically endangered. Unfortunately, scientific data regarding the actual status of populations is lacking. We combined satellite image analysis, species-specific habitat assessment, and a field survey technique using playback to focus conservation efforts for this species. First, we identified remaining forest via a LANDSAT mosaic and then applied species-specific criteria to delineate remaining forest with potential to hold populations. By combining this with the historical distribution from ecological niche modeling and predicted hunting intensity we generated a species-specific landscape map. Within our study area, forest capable of sustaining Ateles fusciceps covers 5872 km², of which 2172 km² (40%) is protected. Unprotected forest considered suitable for Ateles fusciceps extends to 3700 km² but within this only 989 km² (23%) is under low hunting pressure and likely to maintain healthy populations of Ateles fusciceps. To overcome problems of sampling at low primate density and in difficult mountain terrain we developed a field survey technique to determine presence and estimate abundance using acoustic sampling. For sites under low hunting pressure density of primates varied with altitude. Densities decreased from 7.49 individuals/km² at 332 masl to 0.9 individuals/km² at 1570 masl. Based on combining data sets in a gap analysis, we recommend conservation action focus on unprotected lowland forest to the south and west of the Cotacachi-Cayapas Ecological Reserve where hunting pressure is low and population densities of Ateles fusciceps are greatest.     

Density and Spatial Distribution of Buffy-tufted-ear Marmosets (<Emphasis Type="Italic">Callithrix aurita</Emphasis>) in a Continuous Atlantic Forest

The continued degradation of forest habitats and isolation of fragmented populations means that the conservation of endemic marmosets in the Brazilian Atlantic forest depends on human interventions including legal protection. Population monitoring is required to ensure effective management and appropriate allocation of conservation resources; however, deriving estimates of population metrics such as density within heterogeneous environments is challenging. We aimed to quantify the population density and spatial distribution of buffy-tufted-ear marmosets (Callithrix aurita) in the northern region of Serra-do-Mar State Park. We incorporated habitat suitability as quantified by a niche modeling algorithm (MAXENT) to refine density estimates obtained via distance methods. We used 6 environmental predictors to model the distribution of Callithrix aurita and used the resulting MAXENT niche model to identify environmental conditions that represent suitable habitat for this species. We used 877.7 km of line transect surveys and distance methods to derive estimates of 2.19 groups or 7.55 individuals/km² from direct observations (n = 40), providing an overall population estimate of 1892 (95% CI = 1155–3068) individuals in 250.7 km² of Atlantic forest. Our refined density estimate, obtained by combining distance methods and a niche model, yielded a result of 1386 individuals. Suitable habitat was not uniformly distributed across the study area and was most strongly associated with altitude and the type of vegetation cover. We provide a review of previous surveys and find this is the largest known population of Callithrix aurita. Our refinement of density estimates provides a simple and informative addition to the primatologist’s toolbox.     

Potential distribution,absolute density,and population size of Gray‐backed Hawks (Pseudastur occidentalis) in a protected area in northwest Peru

Estimates of density and population size are fundamental in assessing population trends and ultimately in informing conservation management. Although the abundance of raptors is often expressed as indices of relative abundance, these can be poor correlates of absolute density. In 2008–2009, I calculated the absolute density and population size of Gray‐backed Hawks (Pseudastur occidentalis), an endangered species and Tumbesian endemic, using line transect counts in four different habitat types in a protected area in northwestern Peru. The absolute density of Gray‐backed Hawks in northwest Peru was estimated to be 0.65 individuals km^?2, and the most suitable habitat for the species was located in the provinces of Manabí, Guayas, and Santa Elena in Ecuador, and Tumbes and Piura departments in Peru. The population of Gray‐backed Hawks in my study areas in Tumbes was estimated to be 136, with 94% occurring in dry deciduous and deciduous forest. Because ～60% of all detections in my study were made outside strictly protected areas, including the recently created Angostura‐Faical Regional Conservation Area, conservation of the remaining, non‐protected forests patches in Peru and Ecuador should be a high priority. The current global population of Gray‐backed Hawks has been estimated to be between 250 and 999 birds and declining due to ongoing habitat destruction and fragmentation. Small populations in small habitat fragments, like those in my study area, have high conservation potential, provided that populations are not isolated, and hence should be the focus of constant monitoring.     

Are Montane Forests Demographic Sinks for Bornean White‐bearded Gibbons Hylobates albibarbis?

I estimated habitat-specific population densities for a population of Bornean white-bearded gibbons Hylobates albibarbis inhabiting seven distinct forest types at Gunung Palung National Park, West Kalimantan, Indonesia. Population densities in montane forests (0.44 individuals/km²) were almost ten times lower than those in the next best habitat (upland granite forest; 4.2 individuals/km²) and far lower than those in lowland forest types. Demographic data on 33 gibbon groups living across the seven forest types showed that reproduction was substantially depressed in montane forests compared to high-quality lowland habitats. A simple model suggests that montane forests are demographic sinks for gibbons at Gunung Palung. Follow-up data from observations of montane groups 5 yr after the initial observation period support this result. As high-quality lowland forests (source habitat for gibbons) are being disproportionately lost in and around Gunung Palung National Park due to illegal logging and conversion to oil palm plantations, an increasing percentage of the remaining forest in the park comprises sink habitat for gibbons. This result has disquieting implications for the long-term viability of gibbon populations at Gunung Palung. In addition, as montane forests are generally low-quality habitat for most rainforest vertebrates, and since lowland forests are being lost at alarming rates across the tropics, source-sink population dynamics similar to those I describe here may characterize populations of other tropical vertebrate species.     

Non-invasively determined multi-site variation in pine marten <Emphasis Type="Italic">Martes martes</Emphasis> density,a recovering carnivore in Europe

Pine martens (Martes martes) are subject to national and international conservation legislation throughout most of their European range. Yet population density and abundance estimates, which are a key component of effective conservation management, are lacking in many countries. In this study, a large-scale non-invasive survey was undertaken in 14 forested study sites throughout Ireland to assess variation in pine marten density and abundance. Pine marten hair samples were collected in each study site and analysed using genetic techniques to determine individual identity data. Density and abundance estimates were obtained using spatially explicit capture-recapture models and CAPWIRE. Across all study sites, a total of 93 individual pine marten were identified and captured 217 times. Estimated pine marten density varied from 0 to 2.60 individuals per km² of forested habitat, with all but a single site having estimated densities of ≤1 pine marten per km² of forest habitat. Mean population abundance estimates across all study sites ranged from 0 to 27 individuals. Spatially explicit capture-recapture models on combined data across all 14 study sites provided a mean density estimate of 0.64 (95% CI 0.49–0.81). Combining this with data on the current distribution and estimated area of forest habitat occupied by the species in Ireland, the total pine marten population abundance of pine marten in Ireland was estimated at 3043 (95% CI 2330–3852) individuals. This research has conducted the largest scale investigation of pine marten density and abundance in any part of its global distribution and provided an improved basis for future population assessment and monitoring of this species.     

Line Transect and Triangulation Surveys Provide Reliable Estimates of the Density of Kloss’ Gibbons (Hylobates klossii) on Siberut Island, Indonesia

Estimating population densities of key species is crucial for many conservation programs. Density estimates provide baseline data and enable monitoring of population size. Several different survey methods are available, and the choice of method depends on the species and study aims. Few studies have compared the accuracy and efficiency of different survey methods for large mammals, particularly for primates. Here we compare estimates of density and abundance of Kloss’ gibbons (Hylobates klossii) using two of the most common survey methods: line transect distance sampling and triangulation. Line transect surveys (survey effort: 155.5 km) produced a total of 101 auditory and visual encounters and a density estimate of 5.5 gibbon clusters (groups or subgroups of primate social units)/km². Triangulation conducted from 12 listening posts during the same period revealed a similar density estimate of 5.0 clusters/km². Coefficients of variation of cluster density estimates were slightly higher from triangulation (0.24) than from line transects (0.17), resulting in a lack of precision in detecting changes in cluster densities of <66 % for triangulation and <47 % for line transect surveys at the 5 % significance level with a statistical power of 50 %. This case study shows that both methods may provide estimates with similar accuracy but that line transects can result in more precise estimates and allow assessment of other primate species. For a rapid assessment of gibbon density under time and financial constraints, the triangulation method also may be appropriate.     

Densities,Distributions, and Seasonal Movements of Gorillas and Chimpanzees in Swamp Forest in Northern Congo

The conservation of gorillas (Gorilla spp.) and chimpanzees (Pan troglodytes) depends upon knowledge of their densities and distribution throughout their ranges. However, information about ape populations in swamp forests is scarce. Here we build on current knowledge of ape populations by conducting line transect surveys of nests throughout a reserve dominated by swamp forest: the Lac Télé Community Reserve in northern Congo. We estimated gorilla and chimpanzee densities, distributions across habitats, and seasonal changes in abundance. Gorilla density was 2.9 gorillas km^–2, but densities varied by habitat (0.3–5.4 gorillas km^–2) with highest densities in swamp forest and terra firma mixed forest. Average chimpanzee density is 0.7 chimpanzees km^–2 (0.1–1.3 chimpanzees km^–2), with highest densities in swamp forest. Habitat was the best predictor of ape nest abundance, as neither the number of human indices nor the distance from the nearest village predicted nest abundance. We recorded significantly greater numbers of apes in terra firma forest during the high-water season than the low-water season, indicating that many gorillas and chimpanzees are at times concentrated in terra firma forest amid a matrix of swamp forest. Seasonally high numbers of apes on terra firma forest islands easily accessible to local people may expose them to substantial hunting pressure. Conversely, the nearly impenetrable nature of swamp forests and their low value for logging makes them promising sites for the conservation of apes.     

Pileated Gibbon Density in Relation to Habitat Characteristics and Post‐logging Forest Recovery

ABSTRACT Although it is known that forest loss and degradation negatively impact most forest‐dwelling primates, such relationships are difficult to quantify because many primates are difficult to survey over large areas. Furthermore, recovery times are also difficult to assess due to a lack of long‐term data. Here, we determined how forest characteristics and habitat disturbance correlate with the abundance of pileated gibbons, Hylobates pileatus. We studied a population in Khao Ang Rue Nai Wildlife Sanctuary in southeastern Thailand, assessed its density using an auditory method combined with distance sampling at 24 randomly placed sample sites. In addition, we determined how simple forest structural characteristics and habitat disturbance correlate with the gibbon abundance. Average gibbon density per site was 1.02 ± 0.16 (SE) groups/km² (range 0–2.74). Bivariate analyses indicated that densities depended on food tree biomass, level of disturbance, evergreen forest cover, time since protection, and distance to the sanctuary boundary. Multiple regression analysis suggested evergreen forest cover and distance to boundary were the most influential factors. Because evergreen forest cover, time since protection, and habitat disturbance are correlated, these results suggest a direct dependence of gibbon densities on mature, undisturbed evergreen forest. While gibbons can persist in disturbed areas if the forest is protected, it appears that recovery to previous densities may take decades. We suggest that this is due to the slow pace of forest regeneration and/or poor recovery potential of gibbons.     

Impacts of forest gaps on butterfly diversity in a Bornean peat-swamp forest

Forest degradation is leading to widespread negative impacts on biodiversity in South-east Asia. Tropical peat-swamp forests are one South-east Asian habitat in which insect communities, and the impacts of forest degradation on them, are poorly understood. To address this information deficit, we investigated the impacts of forest gaps on fruit-feeding butterflies in the Sabangau peat-swamp forest, Central Kalimantan, Indonesia. Fruit-baited traps were used to monitor butterflies for 3 months during the 2009 dry season. A network of 34 traps (n_gap = 17, n_shade = 17) was assembled in a grid covering a 35 ha area. A total of 445 capture events were recorded, comprising 384 individuals from 8 species and 2 additional species complexes classified to genera. On an inter-site scale, canopy traps captured higher species richness than understory traps; however, understory traps captured higher diversity within each site. Species richness was positively correlated with percent canopy cover and comparisons of diversity indices support these findings. Coupled with results demonstrating morphological differences in thorax volume and forewing length between species caught in closed-canopy traps vs. those in gaps, this indicates that forest degradation has a profound effect on butterfly communities in this habitat, with more generalist species being favored in disturbed conditions. Further studies are necessary to better understand the influences of macro-habitat quality and seasonal variations on butterfly diversity and community composition in South-east Asian peat-swamp forests.     

Density and habitat use of lions and spotted hyenas in northern Botswana and the influence of survey and ecological variables on call-in survey estimation

Top predators significantly impact ecosystem dynamics and act as important indicator species for ecosystem health. However, reliable density estimates for top predators, considered necessary for the development of management plans and ecosystem monitoring, are challenging to obtain. This study aims to establish baseline density estimates for two top predators, spotted hyena and lion, in the Okavango Delta in northern Botswana. Using calling stations, we surveyed free-ranging populations of the two species and investigated methodological variables that might influence results about distributions and densities, including habitat type, seasonality, and different types of playback sounds. Calling stations were distributed over a survey area of approximately 1,800 km² characterized by three major habitat types: mopane woodland, floodplain and mixed acacia sandveld. Results indicate spotted hyenas were evenly distributed independent of habitat type and season throughout the survey area with an overall density estimate of 14.4 adults/100 km². In contrast, lion distribution and density varied significantly with habitat and season. Lion density in the prey-poor mopane woodland was near zero, while in the comparatively prey-rich floodplains it was estimated at 23.1 individuals/100 km² resulting in a weighted average density of 5.8 individuals/100 km² across the entire study area. In testing the effect of varying playback sounds we found that both species were significantly more likely to respond to calls of conspecifics. Our results show how several methodological variables may influence density estimates and emphasize the importance of standardized calling-station survey methods to allow consistent replication of surveys and comparison of results that can be used for landscape-scale monitoring of large predator species.     

A survey of elephants (Loxodonta africana) in the Kahuzi-Biega National Park lowland sector and adjacent forest in eastern Zaire

There has been considerable uncertainty about the abundance estimation of Loxodonta africana within tropical lowland moist forests in Zaire. We surveyed a 15,570 km² area within the forests of eastern Zaire using transect sampling methods and estimated the elephant population to be 3720 (range 2300–5000) individuals. Dung pile densities were significantly different between adjacent settlement, deep forest, and deep forest core strata, with the most remote area harbouring the highest density. Evidence of elephant poaching was encountered throughout the survey area suggesting that elephant populations continue to be at severe risk.     

黑龙江省老爷岭南部穆棱林区马鹿种群分布数量及生境适宜性评价

开展野生动物种群分布数量和生境适宜性评价研究是制定物种科学保护决策的基础和关键。以东北马鹿(Cervus canadensis xanthopygus)为研究对象,于2015—2020年在黑龙江省老爷岭南部穆棱林区,采用大样方调查方法收集马鹿在雪地留下的足迹信息分析马鹿种群数量;通过相机监测、足迹链跟踪和大样方调查3种方法综合收集马鹿活动点信息,利用最大熵(MaxEnt)建模分析马鹿生境适宜性。马鹿种群分布数量研究结果表明,穆棱林区马鹿种群密度为(0.0645±0.009)只/km~2,种群数量为47—61只,主要分布在研究地区南部的和平、龙爪沟和共和林场。生境分析结果表明：人为干扰因子中,居民区对MaxEnt模型的贡献率为44%,马鹿主要在距居民区距离约5 km和10—15 km的区域活动,在偏僻的林间小道和乡村道路马鹿生境适宜性较高,其对模型贡献率分别为16.8%和10.2%;植被因子中,在距常绿针叶林和针阔混交林距离4 km范围内,随距离增加马鹿生境适宜性逐渐降低。生境适宜性分析结果表明,研究地区马鹿适宜生境和次适宜生境面积为87.09 km~2,仅占研究区域的10.39%,主要...