Forest elephant paths and movements at the Odzala National Park, Congo: the role of clearings and Marantaceae forests

The role of forest clearings and Marantaceae forest on elephant movement at the Odzala National Park was studied by describing and mapping elephant paths. Three types of paths were distinguished based on their direction, length, width, elephant activity and the types of forests they cross. They were called boulevards, foraging paths, and clearing alleys. All paths explored were heavily used. Boulevards are used for travelling over long distances (up to 34 km) and for linking up rapidly favourite sites such as clearings. Foraging paths mainly run through the medium-density Marantaceae forests which provide elephants with both herbaceous foods and tree fruit. Clearing alleys form a dense network of tracks around clearings. This network could be a result of an anti-predatory monitoring behaviour of elephants before entering the clearings where they have long experienced heavy poaching. The heavy trampling which results from the elephant activity could contribute to the maintenance of clearings by preventing germination and seedling survival of the numerous seeds dispersed in their dung.     

Long-Term Monitoring of Dzanga Bai Forest Elephants: Forest Clearing Use Patterns

Individual identification of the relatively cryptic forest elephant (Loxodonta cyclotis) at forest clearings currently provides the highest quality monitoring data on this ecologically important but increasingly threatened species. Here we present baseline data from the first 20 years of an individually based study of this species, conducted at the Dzanga Clearing, Central African Republic. A total of 3,128 elephants were identified over the 20-year study (1,244 adults; 675 females, 569 males). It took approximately four years for the majority of elephants visiting the clearing to be identified, but new elephants entered the clearing every year of the study. The study population was relatively stable, varying from 1,668 to 1,864 individuals (including juveniles and infants), with increasingly fewer males than females over time. The age-class distribution for females remained qualitatively unchanged between 1995 and 2010, while the proportion of adult males decreased from 20% to 10%, likely reflecting increased mortality. Visitation patterns by individuals were highly variable, with some elephants visiting monthly while others were ephemeral users with visits separated by multiple years. The number of individuals in the clearing at any time varied between 40 and 100 individuals, and there was little evidence of a seasonal pattern in this variation. The number of elephants entering the clearing together (defined here as a social group) averaged 1.49 (range 1–12) for males and 2.67 (range 1–14) for females. This collation of 20 years of intensive forest elephant monitoring provides the first detailed, long term look at the ecology of bai visitation for this species, offering insight to the ecological significance and motivation for bai use, social behavior, and threats to forest elephants. We discuss likely drivers (rainfall, compression, illegal killing, etc.) influencing bai visitation rates. This study provides the baseline for future demographic and behavioral studies of this population.     

Small-scale dung survey reveals high forest elephant density and preference for mixed species forest in an intact protected area

Understanding the ecological factors influencing African forest elephant (Loxodonta cyclotis) abundance and distribution is crucial for their conservation management in Central Africa. Dung surveys have been conducted at the landscape scale and confirmed the overwhelming impact of anthropogenic activities on forest elephants. We present results from a small-scale survey in a pristine protected area without anthropogenic activities to elucidate the ecological factors influencing forest elephant density. We conducted a line transect dung survey in a small study area (110 km²) around Mbeli Bai, a natural forest clearing in the Nouabalé-Ndoki National Park, Republic of Congo, and compare results with a landscape survey conducted during the same period. We used habitat specific dung decay data collected on site to estimate elephant density using distance sampling. We fitted Generalized Additive Models to elephant dung encounter rate using explanatory variables collected during the transect survey and from geospatial data. The small-scale survey revealed a precise estimate of forest elephant density that was twice as high as the result from a landscape survey with higher density in mixed species forest for the small-scale survey. We could not find an impact of the proximity of forest clearings and proximity to rivers at the small scale. Fine-scale habitat features, e.g. degree of canopy and understorey closure, had little explanatory power for elephant dung encounter rate. Small-scale dung surveys are a useful method to reveal spatio-temporal variation in forest elephant density and distribution which can inform conservation practitioners in a timely manner. Combining monitoring methods at various spatial scales improves our knowledge and conservation efforts of forest elephants. Nouabalé-Ndoki National Park is a stronghold for forest elephants and of global importance for their conservation.

     

Demography of a population with a long history of poaching and the utility of the individual identification technique as a tool for monitoring intermittently studied elephant populations

In many elephant populations in Africa, adverse effects of poaching including altered age and sex structure and long calving intervals continue to negatively impact the rate of recovery. The study reported here characterized the demographic status of the elephant population in Meru National Park, Kenya, so as to determine the size, age and sex structure, and calving interval of the population and to compare its demographic parameters against those from the relatively stable elephant population at Amboseli. Additionally, a demographic study conducted 7 years earlier enabled us to determine the demographic performance of the population and to explicitly test the utility of the individual identification technique in monitoring intermittently studied populations. We found 392 elephants in the park. The proportion of older individuals was lower, and the calving interval was longer than estimates from Amboseli. We recognized 16% of elephants indexed in the previous study. Our results suggest that the individual identification technique may be useful in monitoring demographic changes including poaching in intermittently studied elephant populations. Overall, our results suggest that although the Meru elephant population showed signs of recovery, poaching continues to imperil its recovery.     

Assessing the effects of elephant foraging on the structure and diversity of an Afrotropical forest

African forest elephants (Loxodonta cyclotis) are ecosystem engineers that browse and damage large quantities of vegetation during their foraging and movement. Though elephant trail networks and clearings are conspicuous features of many African forests, the consequences of elephant foraging for forest structure and diversity are poorly documented. In this study in northeastern Gabon, we compare stem size, stem density, proportional damage, species diversity, and species relative abundance of seedlings and saplings in the vicinity of seven tree species that produce elephant-preferred fruits (“elephant trees”) relative to control trees that do not. Across 34 survey trees, with a combined census area of 2.04 ha, we recorded data on 26,128 woody stems in three sizes classes. Compared with control trees, the area around elephant trees had the following: (a) a significantly greater proportion of damaged seedlings and a marginally greater proportion of damaged saplings (with 82% and 24% greater odds of damage, respectively); (b) no significant difference in stem density or species diversity; and (c) a significantly greater relative abundance of seedlings of elephant tree species. Increasing distance away from focal elephant trees was associated with significantly reduced sapling stem damage, significantly increased sapling stem density, and significantly increased sapling species diversity. Considered in sum, our results suggest that elephants can affect the structure and diversity of Afrotropical forests through their foraging activities, with some variation based on location and plant size class. Developing a more complete understanding of elephants’ ecological effects will require continued research, ideally with manipulative experiments.     

Reconciling apparent conflicts between mitochondrial and nuclear phylogenies in African elephants

Conservation strategies for African elephants would be advanced by resolution of conflicting claims that they comprise one, two, three or four taxonomic groups, and by development of genetic markers that establish more incisively the provenance of confiscated ivory. We addressed these related issues by genotyping 555 elephants from across Africa with microsatellite markers, developing a method to identify those loci most effective at geographic assignment of elephants (or their ivory), and conducting novel analyses of continent-wide datasets of mitochondrial DNA. Results showed that nuclear genetic diversity was partitioned into two clusters, corresponding to African forest elephants (99.5% Cluster-1) and African savanna elephants (99.4% Cluster-2). Hybrid individuals were rare. In a comparison of basal forest "F" and savanna "S" mtDNA clade distributions to nuclear DNA partitions, forest elephant nuclear genotypes occurred only in populations in which S clade mtDNA was absent, suggesting that nuclear partitioning corresponds to the presence or absence of S clade mtDNA. We reanalyzed African elephant mtDNA sequences from 81 locales spanning the continent and discovered that S clade mtDNA was completely absent among elephants at all 30 sampled tropical forest locales. The distribution of savanna nuclear DNA and S clade mtDNA corresponded closely to range boundaries traditionally ascribed to the savanna elephant species based on habitat and morphology. Further, a reanalysis of nuclear genetic assignment results suggested that West African elephants do not comprise a distinct third species. Finally, we show that some DNA markers will be more useful than others for determining the geographic origins of illegal ivory. These findings resolve the apparent incongruence between mtDNA and nuclear genetic patterns that has confounded the taxonomy of African elephants, affirm the limitations of using mtDNA patterns to infer elephant systematics or population structure, and strongly support the existence of two elephant species in Africa.     

Changes in Elephant Abundance Affect Forest Composition or Regeneration?

While overall numbers of African elephant have declined dramatically in recent times, some populations are now confined to protected areas and are locally overabundant—an undesirable situation for both biodiversity conservation and elephants. In forested protected areas, options to manage elephants are limited because it is difficult to safely approach animals, yet it is vital that these populations are managed because browsing by elephants can dramatically alter forest ecosystems. Using data collected over 50 yr in Kibale National Park, Uganda, we examine the prediction that increasing elephant numbers and associated changes in their foraging behavior have caused a shift in tree community composition. Although the relative abundance of elephants increased significantly between 1996 and 2010, the population structure of their preferred tree food species did not change, nor did tree community composition change in favor of species able to re‐sprout after elephant damage. Furthermore, over the last 50 yr Kibale elephants have not become more selective foragers, as would be expected if more nutritious tree species were declining. However, elephants are more abundant in disturbed areas dominated by shrubs and grasses and appear to have arrested forest succession in these areas. At their current abundance, elephants have not selectively altered the composition of intact old growth forest, but they do inhibit the regeneration of disturbed areas.     

How selective are elephants as agents of forest tree damage in Bwindi Impenetrable National Park,Uganda?

Elephants are locally concentrated in Bwindi Impenetrable National Park. Vegetation damage attributable to elephants appears to be increasing and may result in the modification of the forest. We examined the implied selectivity of stem damage due to elephants. We followed 26.84 km of recent elephant trails and used 122 plots to document tree damage in relation to species, stem sizes and locations. Of 897 trees (DBH ≥2 cm), 542 (60.4%) were intact, 22 (2.5%) debarked, 274 (30.5%) toppled and 172 (19.2%) had broken branches. Small trees were more likely to be pushed over or have their branches broken, whereas large trees were more commonly debarked. The species most frequently selected for damage included mid‐successional species such as Newtonia buchananii, Myrianthus holstii and Chrysophyllum albidum. These species may be vulnerable to increasing elephant numbers. Our analyses using general linear models indicate that elephants are selective concerning where, how and what tree stems they damage. We found a higher incidence of elephant damage per‐tree stem in open areas than in more closed areas, suggesting feedback in which elephants maintain open habitats that may be conducive for other species such as mountain gorillas. More work is needed to better determine how changing elephant numbers may influence Bwindi's conservation values.     

Estimating population sizes for elusive animals: the forest elephants of Kakum National Park,Ghana

African forest elephants are difficult to observe in the dense vegetation, and previous studies have relied upon indirect methods to estimate population sizes. Using multilocus genotyping of noninvasively collected samples, we performed a genetic survey of the forest elephant population at Kakum National Park, Ghana. We estimated population size, sex ratio and genetic variability from our data, then combined this information with field observations to divide the population into age groups. Our population size estimate was very close to that obtained using dung counts, the most commonly used indirect method of estimating the population sizes of forest elephant populations. As their habitat is fragmented by expanding human populations, management will be increasingly important to the persistence of forest elephant populations. The data that can be obtained from noninvasively collected samples will help managers plan for the conservation of this keystone species.     

Using presence‐only modelling to predict Asian elephant habitat use in a tropical forest landscape: implications for conservation

Aim Asian elephants, Elephas maximus, are threatened throughout their range by a combination of logging, large scale forest conversion and conflict with humans. We investigate which environmental factors, both biotic and abiotic, constrain the current distribution of elephants. A spatially explicit habitat model is constructed to find core areas for conservation and to assess current threats. Location Ulu Masen Ecosystem in the province of Nanggroe Aceh Darussalam on the island of Sumatra, Indonesia. Methods A stratified survey was conducted at 12 sites (300 transects) to establish the presence of elephants. Presence records formed the basis to model potential habitat use. Ecological niche factor analysis (ENFA) is used to describe their niche and to identify key factors shaping elephant distribution. An initial niche model was constructed to describe elephant niche structure, and a second model focused on identifying core areas only. To assess the threat of habitat encroachment, overlap between the elephants’ optimal niche and the occurrence of forest encroachment is computed. Results Elephants were recorded throughout the study area from sea level to 1600 m a.s.l. The results show that the elephant niche and consequently habitat use markedly deviates from the available environment. Elephant presence was positively related to forest cover and vegetation productivity, and elephants were largely confined to valleys. A spatially explicit model showed that elephants mainly utilize forest edges. Forest encroachment occurs throughout the elephants range and was found within 80% of the elephants’ ecological niche. Main conclusions In contrast to general opinion, elephant distribution proved to be weakly constrained by altitude, possibly because of movement routes running through mountainous areas. Elephants were often found to occupy habitat patches in and near human‐dominated areas. This pattern is believed to reflect the displacement of elephants from their former habitat.     

Elephants of south‐east Angola in war and peace: their decline,re‐colonization and recent status

Angola’s intermittent 27‐year civil war displaced over four million people and decimated wildlife populations. During the 1980s, African elephants (Loxodonta africana Blumenbach) in Angola drew international alarm with reports of 100,000 elephants killed. Luiana Partial Reserve (PR), a conservation area in south‐east Angola, was the military operations centre for UNITA (National Union for the Total Independence of Angola), which used elephant ivory to pay for arms and meat. However, the full impact of the civil war on elephants is uncertain because there are no reliable estimates of Angolan elephant populations. Following the end of the civil war in 2002, our three aerial surveys of Luiana PR indicated that elephant numbers are increasing rapidly, from 366 in January 2004 to 1827 in November 2005, and expanding their range in the Reserve. Concurrently, elephants tagged with satellite collars in northern Botswana and the Caprivi Strip, Namibia, moved into Luiana PR. To facilitate re‐colonization and conservation of elephants and other wildlife in Luiana PR, we recommend: (i) realignment of the veterinary fence on the Botswana–Namibia border; (ii) development of effective land use management and anti‐poaching programmes; (iii) clearing of landmines; (iv) designation of the Reserve a national park; and (v) development of ecotourism and community conservation programmes.     

Forest elephant crisis in the Congo Basin

Debate over repealing the ivory trade ban dominates conferences of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Resolving this controversy requires accurate estimates of elephant population trends and rates of illegal killing. Most African savannah elephant populations are well known; however, the status of forest elephants, perhaps a distinct species, in the vast Congo Basin is unclear. We assessed population status and incidence of poaching from line-transect and reconnaissance surveys conducted on foot in sites throughout the Congo Basin. Results indicate that the abundance and range of forest elephants are threatened from poaching that is most intense close to roads. The probability of elephant presence increased with distance to roads, whereas that of human signs declined. At all distances from roads, the probability of elephant occurrence was always higher inside, compared to outside, protected areas, whereas that of humans was always lower. Inside protected areas, forest elephant density was correlated with the size of remote forest core, but not with size of protected area. Forest elephants must be prioritised in elephant management planning at the continental scale.     

普洱市亚洲象栖息地适宜度评价

亚洲象(Elephas maximus)属于我国Ⅰ级保护动物,在中国仅分布于云南省西双版纳国家级自然保护区、普洱市的思茅区、澜沧县和江城县,以及临沧南滚河国家级自然保护区。将普洱全境作为研究区域,利用野外调查数据,结合遥感与地理信息系统技术,运用生态位因子分析(ENFA)模型对普洱市亚洲象的栖息地适宜度进行了评价,并预测了适宜栖息地的分布。发现:普洱市亚洲象栖息地的边际值为0.991,表明亚洲象在普洱市境内对环境变量的选择不是随机的;耐受值为0.315,表明亚洲象在普洱市境内生态位较窄,受环境条件的制约。根据模型计算得到的栖息地适宜度指数,将普洱市的亚洲象栖息地分为最适栖息地,较适栖息地,边际栖息地和非栖息地4个等级,面积分别为409.32、574.32、2909.48、38722.32 km2。最适栖息地仅占全市面积的0.96%,而非栖息地占90.86%。利用GIS和Biomapper 4.0生成亚洲象栖息地分布图,发现普洱境内最适栖息地和较适栖息地面积狭小。对最适栖息地、较适栖息地和边际栖息地进行景观格局分析的结果表明,3种类型的栖息地破碎化均十分严重,连通度较低,栖息地内受到较大程度的人类活动的干扰。因此建议在普洱和西双版纳间尽快建立野生动物生态廊道,以加强亚洲象各种群间的交流。     

A Meta-Analysis of the Impact of African Elephants on Savanna Vegetation

Abstract: Large herbivores such as elephants (Loxodonta africana) apparently have a negative impact on woody vegetation at moderate to high population densities. The confounding effects that fire, drought, and management history have may complicate assignment of such impacts to herbivory. We reviewed 238 studies published over 45 years and conducted a meta-analysis based on 21 studies that provided sufficient information on response of woody vegetation to elephants. We considered size and duration of studies, elephant densities, rainfall, fences, and study outcomes in our analysis. We detected a disproportionate citation of 20 published studies in our database, 15 of which concluded that woody vegetation responded negatively to elephants. Our analysis showed that high elephant densities had a negative effect on woody vegetation but that rainfall and presence of fences influenced these effects. In arid savannas, woody vegetation always responded negatively to elephants. In transitional savannas, an increase in elephant densities did not influence woody vegetation response. In mesic savannas, negative responses of woody vegetation increased when elephants occurred at higher densities, whereas elephants confined by fences also had more negative effects on woody plants than elephants that were not confined. Our analysis suggested that rainfall and fences influenced elephant density related impact and that research results were often site-specific. Local environmental conditions and site-specific objectives should be considered when developing management actions to curb elephant impacts on woody vegetation.     

Elephant calling patterns as indicators of group size and composition: the basis for an acoustic monitoring system

The paper gives evidence that the vocal activity of elephants varies with group size, composition and reproductive status, and that elephants' calling patterns could therefore provide the basis for a remote monitoring system. We examined a 3‐week set of array‐based audio recordings of savanna elephants (Loxodonta africana), searching for diagnostic acoustic parameters. An acoustic array made it possible to locate recorded sounds and attribute the calls to particular elephants or elephant groups. Simultaneous video recordings made it possible to document visible behaviour and roughly correlate it with vocalizations. We compared several measures of call density in elephant groups containing up to 59 individuals, and found that rates of calling increased with increasing numbers of elephants. We divided all call events into three structural types (single‐voice low‐frequency calls, multiple‐voice clustered low‐frequency calls, and single‐voice high frequency calls), and found that the incidence of these varies predictably with group composition. These results suggest the value of a network of listening systems in remote areas for the collection of information on elephant abundance and population structure.     

Single‐nucleotide polymorphism discovery and panel characterization in the African forest elephant

The continuing decline in forest elephant (Loxodonta cyclotis) numbers due to poaching and habitat reduction is driving the search for new tools to inform management and conservation. For dense rainforest species, basic ecological data on populations and threats can be challenging and expensive to collect, impeding conservation action in the field. As such, genetic monitoring is being increasingly implemented to complement or replace more burdensome field techniques. Single‐nucleotide polymorphisms (SNPs) are particularly cost‐effective and informative markers that can be used for a range of practical applications, including population census, assessment of human impact on social and genetic structure, and investigation of the illegal wildlife trade. SNP resources for elephants are scarce, but next‐generation sequencing provides the opportunity for rapid, inexpensive generation of SNP markers in nonmodel species. Here, we sourced forest elephant DNA from 23 samples collected from 10 locations within Gabon, Central Africa, and applied double‐digest restriction‐site‐associated DNA (ddRAD) sequencing to discover 31,851 tags containing SNPs that were reduced to a set of 1,365 high‐quality candidate SNP markers. A subset of 115 candidate SNPs was then selected for assay design and validation using 56 additional samples. Genotyping resulted in a high conversion rate (93%) and a low per allele error rate (0.07%). This study provides the first panel of 107 validated SNP markers for forest elephants. This resource presents great potential for new genetic tools to produce reliable data and underpin a step‐change in conservation policies for this elusive species.     

A Case Study: Fecal Corticosteroid and Behavior as Indicators of Welfare During Relocation of an Asian Elephant

This study was a preliminary investigation of an enzyme immunoassay for measuring fecal glucocorticoid metabolites in a male Asian elephant (Elephas maximus) by investigating changes in behavior and cortisol metabolite excretion associated with a putative stressful event. The study collected fecal samples for 10 days prior to, and 10 days after, 24-hr transport and relocation of the elephant to a new herd. The study measured cortisol metabolites using 2 enzyme immunoassays indicating a 389% and 340% increase in cortisol metabolite excretion following relocation. Maximal cortisol metabolite excretion occurred 2 days after relocation and remained elevated during establishment of the new herd. Stereotypic behavior increased approximately 400% after relocation. The relocation disturbed sleep patterns, the elephant spent less time sleeping during the night, and the elephant slept standing up. These results provide preliminary evidence that noninvasive monitoring of fecal cortisol metabolites can be used to investigate adrenal activity in Asian elephants and may be a safe, practical, and accurate welfare indicator.     

Application of photographic capture–recapture modelling to estimate demographic parameters for male Asian elephants

In addition to the threats of habitat loss and degradation, adult males of the Asian elephant Elephas maximus also face greater threats from ivory poaching and conflict with humans. To understand the impact of these threats, conservationists need robust estimates of abundance and vital rates specifically for the adult male segment of elephant populations. By integrating the identification of individual male elephants in a population from distinct morphology and natural markings, with modern capture–recapture (CR) sampling designs, it is possible to estimate various demographic parameters that are otherwise difficult to obtain from this long-lived and wide-ranging megaherbivore. In this study, we developed systematic individual identification protocols and integrated them into CR sampling designs to obtain capture histories and thereby estimate the abundance of adult bull elephants in a globally important population in southern India. We validated these estimates against those obtained from an independent method combining line-transect density estimates with age–sex composition data for elephants. The sampled population was open to gains and losses between sampling occasions. The abundance of adult males in the 176 km² study area was (SÊ ) = 134(14.20) and they comprised 14% (±1%) of the total elephant population. Time-specific abundance estimates for each sampling occasion showed a distinct increase in adult male numbers over the sampling period, explained by seasonal patterns of local migration. CR-based estimates for adult male abundance closely matched estimates from distance-based methods. Thus, while providing abundance data of comparable rigour and precision, photographic CR methods permit estimation of demographic parameters for the Asian elephant that are both urgently needed and difficult to obtain.     

The elephant population of Samburu and Buffalo Springs National Reserves, Kenya

A 21‐month individual identification project on the Samburu and Buffalo Springs National Reserves' elephant population was conducted between November 1997 and July 1999. The free ranging population, of at least 767 elephants, which relied heavily on areas outside the reserves, was individually identified. The numbers of elephants observed per day fluctuated but were greater during dry periods then wet. However, the sizes of aggregations were greater during wet periods. Preliminary investigation suggested that the population could be divided into two groups, which were designated resident and non‐resident family units. The groups comprised approximately equal numbers of cows and calves, but temporally had different reserve use patterns and calving peaks. The daily numbers of males and musth males were correlated with numbers of females. The reserves appeared to be a focal area for calving, indicating that the study area was of reproductive importance to the population. Demographic data indicated a female biased population sex ratio, with over twice the number of mature females to males. The observed sex skew was greatest for older age classes, and the density of musth bulls in the study area was low. The population was affected by poaching. Continued monitoring will assist conservation efforts by alerting authorities of major demographic or range use changes.     

Trio under threat: can we secure the future of rhinos,elephants and tigers in Malaysia?

Three of Malaysia’s endangered large mammal species are experiencing contrasting futures. Populations of the Sumatran rhino (Dicerorhinus sumatrensis) have dwindled to critically low numbers in Peninsular Malaysia (current estimates need to be revised) and the state of Sabah (less than 40 individuals estimated). In the latter region, a bold intervention involving the translocation of isolated rhinos is being developed to concentrate them into a protected area to improve reproduction success rates. For the Asian elephant (Elephas maximus), recently established baselines for Peninsular Malaysia (0.09 elephants/km² estimated from one site) and Sabah (between 0.56 and 2.15 elephants/km² estimated from four sites) seem to indicate globally significant populations based on dung count surveys. Similar surveys are required to monitor elephant population trends at these sites and to determine baselines elsewhere. The population status of the Malayan tiger (Panthera tigris jacksoni) in Peninsular Malaysia, however, remains uncertain as only a couple of scientifically defensible camera-trapping surveys (1.66 and 2.59 tigers/100 km² estimated from two sites) have been conducted to date. As conservation resources are limited, it may be prudent to focus tiger monitoring and protection efforts in priority areas identified by the National Tiger Action Plan for Malaysia. Apart from reviewing the conservation status of rhinos, elephants and tigers and threats facing them, we highlight existing and novel conservation initiatives, policies and frameworks that can help secure the long-term future of these iconic species in Malaysia.