Human impact on wildlife populations within a protected Central African forest

This paper addresses the effect of human activities on the density of large mammals in the Dzanga‐Ndoki National Park and the adjacent Dzanga‐Sangha Reserve in the Central African Republic. Between six and eight 20 km long permanent transects were walked on a monthly basis from January 1997 to August 1999 to assess large mammal populations as well as human intrusion. There were no obvious seasonal or monthly trends in elephant, gorilla or non‐human primate densities. Overall, it appears that human activities negatively influence the distribution of most of the large forest animals in Dzanga‐Sangha. Elephants in particular were significantly less common in areas used by humans, but also other species such as non‐human primates showed lower densities closer to the main road and the town of Bayanga. This study confirms the findings of previous studies that roads have a negative impact on wildlife populations. Results of this study stress the need for conservation of large uninterrupted forest blocks to maintain wildlife populations at normal levels. Simply creating roads, even within a protected Central African forest, is likely to have negative impacts on wildlife populations.     

我国道路对野生动物影响研究的现状与挑战

全球交通基础设施网络的不断扩张导致的栖息地丧失和破碎化已成为生物多样性下降的主要影响因素之一。国外开展了大量的道路对野生动物生存影响的研究, 相对而言, 我国在该领域的研究刚刚起步。本文通过总结截止于2021年国内的144篇案例研究文献以及新浪微博中210条道路交通伤害信息, 将我国道路对野生动物的影响分为栖息地丧失、栖息地破碎化、回避或聚集路边、阻碍或促进迁移、种群隔离、野生动物通道和道路交通伤害等方面, 从研究方法、研究地点、研究物种和研究结果等不同角度进行梳理和总结。近年来, 我国的相关研究呈现不断增长的趋势, 研究地点主要集中在可可西里、长白山和秦岭地区; 研究物种主要为青藏高原有蹄类、大熊猫(Ailuropoda melanoleuca)和亚洲象(Elephas maximus)。未来重点发展方向应包括: (1)道路野生动物基础数据采集平台建设; (2)我国不同动物地理分区的道路野生动物相关研究; (3)深入开展学科交叉与部门合作以及国际交流合作。公众在社交媒体发布的相关信息表明近年来公众对道路交通伤害问题越来越关注, 未来开展基于公民科学收集道路交通伤害数据具有迫切性和可行性。     

Genomic divergence across ecological gradients in the Central African rainforest songbird (Andropadus virens)

The little greenbul, a common rainforest passerine from sub‐Saharan Africa, has been the subject of long‐term evolutionary studies to understand the mechanisms leading to rainforest speciation. Previous research found morphological and behavioural divergence across rainforest–savannah transition zones (ecotones), and a pattern of divergence with gene flow suggesting divergent natural selection has contributed to adaptive divergence and ecotones could be important areas for rainforests speciation. Recent advances in genomics and environmental modelling make it possible to examine patterns of genetic divergence in a more comprehensive fashion. To assess the extent to which natural selection may drive patterns of differentiation, here we investigate patterns of genomic differentiation among populations across environmental gradients and regions. We find compelling evidence that individuals form discrete genetic clusters corresponding to distinctive environmental characteristics and habitat types. Pairwise F_ST between populations in different habitats is significantly higher than within habitats, and this differentiation is greater than what is expected from geographic distance alone. Moreover, we identified 140 SNPs that showed extreme differentiation among populations through a genomewide selection scan. These outliers were significantly enriched in exonic and coding regions, suggesting their functional importance. Environmental association analysis of SNP variation indicates that several environmental variables, including temperature and elevation, play important roles in driving the pattern of genomic diversification. Results lend important new genomic evidence for environmental gradients being important in population differentiation.     

Census and distribution of large carnivores in the Tsavo national parks,a critical east African wildlife corridor

Kenya's Tsavo National Parks are a critical conservation area and the only wilderness corridor through densely populated human-dominated landscapes stretching from the East African coast to Lake Victoria, separating extensive undeveloped grasslands south of the equator from the undeveloped semiarid bushlands to the north. At nearly 21,000 km², Tsavo is one of four lion strongholds in East Africa and part of Africa's most important populations of all other large African carnivores. To provide baseline data on the status of large carnivores, a track survey was undertaken in 2013. Lions and both hyaena species were widely distributed across both parks, while cheetahs and wild dogs were more patchily distributed. Spotted hyaenas were the most abundant, with an estimated population of 3,903 ± 514 (95% CI), followed by lion (706 ± 201), striped hyaena (679 ± 144), leopard (452 ± 98), cheetah (154 ± 74) and wild dog (111 ± 92). Tsavo's carnivores suffer from bushmeat poaching, illegal grazing and retaliatory killing, and increasing human numbers on its periphery. Given Tsavo's importance as a stronghold for lions and an ecological corridor, increased investment in effective protection is strongly recommended. Evaluating trends will require complementary techniques in light of intensive monitoring requirements.     

Dung beetles in a Central Amazonian rainforest and their ecological role as secondary seed dispersers

Abstract 1. The role of several factors that affect the composition of the dung beetle assemblages in an Amazonian rainforest was quantified, together with the effect of these factors on the role that dung beetles play as secondary seed dispersers. 2. A total of 61 dung beetle species was captured during 3360 h of trapping. During nocturnal trapping periods, more dung beetles, of larger mean size, and more species were captured per trap than during diurnal trapping periods. 3. During the rainy season, more dung beetle species were captured per trap than during the dry season, but the number of individuals and their mean size did not vary between seasons. 4. Bait size had a significant effect on the mean number of beetles and mean number of species but not on mean beetle size. As bait size increased from 5, 10, 25, to 50 g, more beetles and more species were captured per trap. 5. Between 6 and 73% of plastic beads, used as seed mimics, were buried by dung beetles at depths that ranged from 0.5 to 7 cm. Both the proportion of beads buried and burial depth decreased with increasing bead size, and increased with increasing amounts of dung surrounding each bead (5, 10, and 25 g). 6. The proportion of buried seeds for three species varying in size between 5 and 27 mm, increased with increasing dung beetle size, using beetles of seven sizes, varying between 10 and 25 mm. 7. Seeds surrounded by dung were buried more often and more deeply when placed on the forest floor during the late afternoon than when placed during the early morning. Seeds were also buried more often when placed on the forest floor during the rainy season than when placed during the dry season, but season had no effect on burial depth. 8. Forests in Central Amazonia hold a rich dung beetle community that plays an active role in secondary seed dispersal, and consequently in plant regeneration. The interaction between seeds and beetles is complex because it is affected by many factors.     

Pooling local expert opinions for estimating mammal densities in tropical rainforests

Methods currently used for assessing wildlife density in rainforests are time and money consuming. The precision of the most commonly used methods is disputed, but accepted because more exact methods are not available. In this study a new method of wildlife density estimation is explained. The new method is less time and money consuming, but yields comparable results with classical methods. The method was tested in the field in Cameroon and compared with transect surveys in the area and with relevant literature. The Pooled Local Expert Opinion (PLEO) method is based on the knowledge of local experts. A number of hunters were asked to estimate wildlife abundance in a specified area, after which the density/km² was calculated for 33 wildlife species. These estimates were pooled and extrapolated for the whole study area. Elephant (Loxodonta africana) density outside the National Park was estimated to be 0.06 animals/km², and 0.3 inside. Buffalo (Syncerus caffer) density for the study area was estimated at 0.2 animals/km² and gorilla (Gorilla gorilla) density at 1.05 per km². Transect surveys carried out at the same time for considerably more money, taking far more time, produced too few data to calculate densities. The evaluation of the PLEO method was favourable and the method offers a substitute for conventional methods of estimating wildlife density in rainforests. The methodology is simple and it can be incorporated in many tropical biodiversity and conservation projects. It can also be used for long-term monitoring of wildlife status in a given area. In contrast with classical methods, the PLEO method is low in cost and assures local ownership of the results.     

Spoor density as a measure of true density of a known population of free-ranging wild cheetah in Botswana

Knowledge of the abundance of animal populations is essential for their management and conservation. Determining reliable measures of abundance is, however, difficult, especially with wide-ranging species such as cheetah Acinonyx jubatus . This study generated a correction factor to calculate true cheetah density from spoor survey data and subsequently tested its accuracy using the following season's data. Data were collected from October 2005 to December 2006 on a known population of wild, free-ranging cheetah in the Jwana Game Reserve, Botswana. The cheetahs in the area were captured, tagged and photographed. The reserve was divided into twelve 9 km transects covering all vegetation types and prey densities. The total sampling distance was 8226 km, with a spoor density of 2.32 individual cheetah spoor per 100 km². To determine a precise and accurate spoor density, it was necessary to sample for a longer period during the dry season (April–September) than during the wet season (October–March). This difference may be due to cheetah behavioural changes with seasonal variations in habitat and prey. The true density was 5.23 cheetahs  per 100 km² ranging from 3.33 to 7.78 at the low and high points of the population, respectively. A positive linear correlation between spoor and true density was observed. This relationship differed in the wet and dry season and required refinement with the following season's data. Correction factors may be viable, but require further testing taking the behavioural responses to seasonal, habitat and prey variations into consideration.     

Population genomics as a new tool for wildlife management

Admixture and introgression have varied effects on population viability and fitness. Admixture might be an important source of new alleles, particularly for small, geographically isolated populations. However, admixture might also cause outbreeding depression if populations are adapted to different ecological or climatic conditions. Because of the emerging use of translocation and admixture as a conservation and wildlife management strategy to reduce genetic load (termed genetic rescue), the possible effects of admixture have practical consequences ( Bouzat et al. 2009 ; Hedrick & Fredrickson 2010 ). Importantly, genetic load and local adaptation are properties of individual loci and epistatic interactions among loci rather than properties of genomes. Likewise, the outcome and consequences of genetic rescue depend on the fitness effects of individual introduced alleles. In this issue of Molecular Ecology, Miller et al. (2012) use model‐based, population genomic analyses to document locus‐specific effects of a recent genetic rescue in the bighorn sheep population within the National Bison Range wildlife refuge (NBR; Montana, USA). They find a subset of introduced alleles associated with increased fitness in NBR bighorn sheep, some of which experienced accelerated introgression following their introduction. These loci mark regions of the genome that could constitute the genetic basis of the successful NBR bighorn sheep genetic rescue. Although population genomic analyses are frequently used to study local adaptation and selection (e.g. Hohenlohe et al. 2010 ; Lawniczak et al. 2010 ), this study constitutes a novel application of this analytical framework for wildlife management. Moreover, the detailed demographic data available for the NBR bighorn sheep population provide a rare and powerful source of information and allow more robust population genomic inference than is often possible.     

Interactions between large African browsers and thorny Acacia on a wildlife ranch in Kenya

Some plants respond to browsing with compensatory regrowth of plant tissues and with increased thorn growth. Associations between browsers and their preferred forage were examined through wandering quarter vegetation sampling and observational studies in an effort to understand how some plants respond to browsing by large African herbivores. Acacia seyal (n = 2680) A. drepanolobium (n = 1850), and Balanites glabra (n = 960) were three species of frequently browsed indigenous plants examined on Game Ranching Ltd. in Kenya. There were several statistically significant associations revealed. Individual A. seyal exposed to intensive browser utilization were observed to lose shoot tips, produce long thorns, and have relatively few flowers and fruits. Browser utilization was associated with increased lateral branching in A. drepanolobium and with an increased occurrence of short, thickened spines in B. glabra. Thorns, spines and flowers were measurable indicators of relative browser utilization, and may be useful features to monitor in the management of large African mammals and their prickly forage     

保护地旅游公路的野生动物通道设计原则与技术参数

保护地以其丰富的生物多样性和优美的自然环境为生态旅游的开展提供了基础条件。近年来, 保护地的生态旅游与旅游道路建设得到了飞速发展。旅游公路的修建, 在促进经济发展的同时, 也带来了野生动物致死、基因隔离、栖息地丧失、生境破碎化等一系列生态问题。因此设立合适的野生动物通道作为一种有效方式, 成为缓解公路对野生动物负面影响的主要途径。本文基于动物通道相关研究, 提出通道设计应遵从针对性、科学性、持续有效性、可行性四条原则, 道路生态学与保护生物学相关理论、保护地管理法规与管理规划、关键物种或类群生态学特性与栖息地现状以及沿线地形地貌特征都应作为通道设置的参考依据; 并从通道建设的数量、位置、类型、尺寸、表面设计、配套设施以及后期监测等方面提出了通道建设的技术参数。为长期有效地发挥野生动物通道的生态功能, 建议制定通道建设技术规范, 细化通道技术参数, 积极开展科研监测, 以缓解道路对野生动物的影响。     

Evolutionary consequences of human disturbance in a rainforest bird species from Central Africa

Relatively little attention has been directed towards understanding the impacts of human disturbance on evolutionary processes that produce and maintain biodiversity. Here, we examine the influence of anthropogenic habitat changes on traits typically associated with natural and sexual selection in the little greenbul (Andropadus virens), an African rainforest bird species. Using satellite remote-sensing and field survey data, we classified habitats into nonhuman-altered mature and human-altered secondary forest. Mature rainforest consisted of pristine rainforest, with little or no human influence, and secondary forest was characterized by plantations of coffee and cacao and high human impacts. Andropadus virens abundance was higher in secondary forest, and populations inhabiting mature rainforest were significantly larger in wing and tarsus length and bill size; characters often correlated with fitness. To assess the extent to which characters important in sexual section and mate choice might be influenced by habitat change, we also examined differences in plumage colour and song. Plumage colour and the variance in plumage luminance were found to differ between forest types, and song duration was found to be significantly longer in mature forest. The possible adaptive significance of these differences in traits is discussed. Despite relatively high levels of gene flow across habitats, amplified fragment length polymorphism analysis revealed that a small proportion of high-F(ST) loci differentiated mature from secondary forest populations. These loci were significant outliers against neutral expectations in a simulation analysis, suggesting a role for divergent selection in differentiation across habitats. A distance-based redundancy analysis further showed that forest type as defined by remote-sensing variables was significantly associated with genetic dissimilarities between habitats, even when controlling for distance. The observed shifts in morphology, plumage and song were consistent with divergent selection on heritable variation, but a role for plasticity cannot be ruled out. Results suggest that anthropogenic habitat changes may have evolutionary consequences, with implications for conservation and restoration.     

Contribution of tree species to the biodiversity of a 1ha Old World rainforest in Brunei, Borneo

Tree biodiversity data is presented for a 1-ha permanent study plot on a low slope position of the Kuala Belalong valley in Temburong District, Brunei, Borneo. This is the first study in the region to document the tree flora of a low slope. All trees 5cm at 1.3m were mapped, measurements of dbh and height taken, and identified to species and morpho-species level. The total and relative values of each family for density, diversity, dominance and Importance Value Indices were calculated. A total of 1062 stems were recorded on the plot (1019 live, 43 dead) with a total of 278 species representing 110 genera in 49 families. The most ecologically significant family as determined by the Family Importance Value (FIV) was Euphorbiaceae with a value of 40 and'the'most significant species, using the Importance Value (IV), was morpho-speciesFordia splendissima with an IV of 29. The total basal area of all living trees was 31.43m². Forest structure was marked by a few tall (>45m) emergents, for example,Koompassia excelsa, Crypteronia griffithii and two species of the Dipterocarpaceae family, however, lower understorey and sub-canopy species dominated the plot with the average height of all individuals over the hectare being 11m.     

Validation of a landscape‐scale planning tool for cavity‐dependent wildlife

Tree cavities provide important habitat for wildlife. Effective landscape‐scale management of cavity‐dependent wildlife requires an understanding of where cavities occur, but tree cavities can be cryptic and difficult to survey. We assessed whether a landscape‐scale map of mature forest habitat availability, derived from aerial photographs, reflected the relative availability of mature trees and tree cavities. We assessed cavities for their suitability for use by wildlife, and whether the map reflected the availability of such cavities. There were significant differences between map categories in several characteristics of mature trees that can be used to predict cavity abundance (i.e. tree form and diameter at breast height). There were significant differences between map categories in the number of potential cavity bearing trees and potential cavities per tree. However, the index of cavity abundance based on observations made from the ground provided an overestimate of true cavity availability. By climbing a sample of mature trees we showed that only 5.1% of potential tree cavities detected from the ground were suitable for wildlife, and these were found in only 12.5% of the trees sampled. We conclude that management tools developed from remotely sensed data can be useful to guide decision‐making in the conservation management of tree cavities but stress that the errors inherent in these data limit the scale at which such tools can be applied. The rarity of tree cavities suitable for wildlife in our study highlights the need to conserve the tree cavity resource across the landscape, but also the importance of increasing the accuracy of management tools for decision‐making at different scales. Mapping mature forest habitat availability at the landscape scale is a useful first step in managing habitat for cavity‐dependent wildlife, but the potential for overestimating actual cavity abundance in a particular area highlights the need for complementary on‐ground surveys.     

Ant mosaics in a tropical rainforest in Australia and elsewhere: A critical review

Abstract The concept of ‘ant mosaics’ has been established to describe the structure of arboreal ant communities in plantations and other relatively simple forest systems. It is essentially built upon the existence of negative and positive associations between ant species plus the concept of dominance hierarchies. Whether this concept can be applied to ant communities in more complex mature tropical rain forests has been questioned by some authors. Here we demonstrate that some previous attempts to prove or disprove the existence of such ant mosaics sampled by knockdown insecticide canopy fogging in near pristine tropical forests may have been thwarted by poor statistical power and too coarse spatial resolution, and the conclusions may be highly dependent on ant species and forest stratum selected for the study. Moreover, the presence or absence of ant mosaics may be driven by the density of suitable resources. We use an intensively studied ant community in the lowland rainforests of North‐East Queensland, Australia to outline processes that may lead to ant mosaic patterns, reasoning that competition for highly predictable resources in space and time such as honeydew and nectar is a fundamental process to maintain the mosaic structure. Honeydew and nectar sources, particularly their amino acids, are of crucial importance for nourishment of arboreal ant species. We use canopy fogging data from the same site in Australia and from two mature rainforests in South‐East Asia to compare spatial avoidance and co‐occurrence patterns implied by ant mosaics. Significant negative and positive associations were found among the three most abundant ant species in each dataset. Several problems with such spatial analyses are discussed, and we suggest that studies of ant mosaics in complex rainforest communities would benefit from a more focused approach on patterns of resource distribution and their differential utilisation by ants.     

Investigating the feasibility of a passive tracking index for monitoring wildlife in the Lower Omo Valley, Ethiopia

In many places in Africa, constraints in human, financial and physical resources are common problems that limit the effectiveness of wildlife researchers and managers. In an attempt to identify a useful tool for monitoring African wildlife populations, we tested a passive tracking index (PTI) methodology on a unique wildlife resource area in the Lower Omo Valley, Ethiopia. The methodology had previously proved valuable for monitoring a wide variety of wildlife species, including ungulates and carnivores in North America and Australia. Two ungulates (lesser kudu and dikdik), a carnivore (hyaena), a primate (baboon), and a ground foraging bird (guineafowl) were simultaneously indexed. In addition, single observations were recorded for genet, serval and caracal. The species indexed also represent the broad needs for monitoring wildlife. The mammal species are of economic importance to the region through sport hunting. Two of the species, hyaenas and baboons, potentially conflict with human agricultural interests through depredations on livestock and crop production. Anthrax periodically decimates the wildlife in the Lower Omo Valley, Ethiopia, but losses of many species are difficult to observe or quantitatively document. The PTI is a simple‐to‐apply, easy‐to‐calculate means to quantify simultaneously population trends for multiple species, and particularly applicable to sustainable harvest by sport hunting, human–wildlife conflicts, and impacts and recovery from wildlife disease.     

Comparison of long‐stem and standard tube‐stock performance 5 years after planting in a rainforest edge on the Central Coast of NSW

Adoption of the long‐stem planting technique in riparian and nonriparian environments is increasing, despite few scientific studies examining whether the technique improves restoration outcomes. Here, we report on the results of an experiment that compares the performance of long‐stem and standard tube stock planted within a rainforest edge. Our results showed that planting technique had no significant effect on the growth and survival of Cheese Tree (Glochidion ferdinandi) and Scentless Rosewood (Synoum glandulosum) individuals, 5 years postplanting. Our findings suggest that long‐stem planting does not enhance tube‐stock performance of these two species, at least under the relatively benign environmental conditions of this study. We recommend that further tests of the technique should focus on habitats where inputs of physical energy are dominant (e.g. rivers, coastal foredunes) and in locations where (and when) growing conditions are particularly harsh.