Physiological indicators of stress in African forest elephants (Loxodonta africana cyclotis) in relation to petroleum operations in Gabon,Central Africa

Aim Human activities are major determinants of forest elephant (Loxodonta africana cyclotis) distribution in Gabon, but the types and intensity of disturbance that elephants can tolerate are not known. We conducted dung surveys within the Gamba Complex of Protected Areas in SW Gabon to examine (1) the feasibility of noninvasive faecal analyses for monitoring stress physiology, and (2) the influence of petroleum operations on stress levels in forest elephants. Location Gabon, Central Africa. Methods We identified multiple dung piles from the same individual by matching their eight‐locus microsatellite genotypes, and measured faecal concentrations of glucocorticoid metabolites as an indicator of stress in areas subject to different levels of disturbance: (1) Loango National Park (2) an ‘industrial corridor’ dominated by oil fields, and (3) a nearby area of human settlements. Results We obtained unique microsatellite genotypes and faecal glucocorticoid metabolite (FGM) concentrations for 150 forest elephant individuals, which is the largest hormonal data set for wild African forest elephants to date. Adults exhibited higher mean FGM concentrations than juveniles, and in contradiction of our expectations of chronic stress around oil fields, elephants in Loango National Park exhibited significantly higher FGM concentrations than elephants in the industrial corridor. Main conclusions We argue that forest elephants in the industrial corridor of the Gamba Complex have become acclimated to oil fields, resulting in part from oil company regulations that minimize stressful interactions between elephants and petroleum operations. Our findings for a flagship species with substantial ecological requirements bode well for other taxa, but additional studies are needed to determine whether oil operations are compatible over their life span with rain forest ecosystems in Central Africa.     

The ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild African elephants

Many social animals live in stable groups. In contrast, African savannah elephants (Loxodonta africana) live in unusually fluid, fission-fusion societies. That is, 'core' social groups are composed of predictable sets of individuals; however, over the course of hours or days, these groups may temporarily divide and reunite, or they may fuse with other social groups to form much larger social units. Here, we test the hypothesis that genetic relatedness predicts patterns of group fission and fusion among wild, female African elephants. Our study of a single Kenyan population spans 236 individuals in 45 core social groups, genotyped at 11 microsatellite and one mitochondrial DNA (mtDNA) locus. We found that genetic relatedness predicted group fission; adult females remained with their first order maternal relatives when core groups fissioned temporarily. Relatedness also predicted temporary fusion between social groups; core groups were more likely to fuse with each other when the oldest females in each group were genetic relatives. Groups that shared mtDNA haplotypes were also significantly more likely to fuse than groups that did not share mtDNA. Our results suggest that associations between core social groups persist for decades after the original maternal kin have died. We discuss these results in the context of kin selection and its possible role in the evolution of elephant sociality.     

Patterns of molecular genetic variation among African elephant populations

The highly threatened African elephants have recently been subdivided into two species, Loxodonta africana (savannah or bush elephant) and L. cyclotis (forest elephant) based on morphological and molecular studies. A molecular genetic assessment of 16 microsatellite loci across 20 populations (189 individuals) affirms species level genetic differentiation and provides robust genotypic assessment of species affiliation. Savannah elephant populations show modest levels of phylogeographic subdivision based on composite microsatellite genotype, an indication of recent population isolation and restricted gene flow between locales. The savannah elephants show significantly lower genetic diversity than forest elephants, probably reflecting a founder effect in the recent history of the savannah species.     

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.     

Using genetic analysis to estimate population size,sex ratio,and social organization in an Asian elephant population in conflict with humans in Alur,southern India

With growing human and, possibly, elephant populations and a drastic increase in anthropogenic activities, human–elephant conflict in Asia has been on the rise. The Alur area in Karnataka state, southern India, is one such case in point, which has witnessed increasing levels of human–elephant conflict over the last two decades. The tiny, moderately protected habitat available for elephants in this human-dominated landscape does not appear to be able to support elephants over the long term. Options to deal with the escalating conflict include translocation of elephants, bringing elephants into captivity, and culling. We carried out a molecular genetic study of elephants in the Alur area to estimate the minimum number of elephants using the area, the sex ratio, genetic relatedness between individuals, and genetic structure with regard to the larger population in the landscape, so that informed management decisions could be made. Fresh dung samples were collected from the field and genotyped using 12 microsatellite loci. We found 29 unique individuals in the population, comprising 17 females and 12 males of different age classes. Relatedness between females suggested independent colonisations by discrete, small groups rather than by one cohesive clan of related females. This obviates the need for a single solution for dealing with all the females in the area in order to maintain social integrity, and has implications in terms how these elephants can be dealt with. We demonstrate how social organization inferred through molecular data from non-invasive sampling can inform management decisions.     

The evolution and phylogeography of the African elephant inferred from mitochondrial DNA sequence and nuclear microsatellite markers

Recent genetic results support the recognition of two African elephant species: Loxodonta africana, the savannah elephant, and Loxodonta cyclotis, the forest elephant. The study, however, did not include the populations of West Africa, where the taxonomic affinities of elephants have been much debated. We examined mitochondrial cytochrome b control region sequences and four microsatellite loci to investigate the genetic differences between the forest and savannah elephants of West and Central Africa. We then combined our data with published control region sequences from across Africa to examine patterns at the continental level. Our analysis reveals several deeply divergent lineages that do not correspond with the currently recognized taxonomy: (i) the forest elephants of Central Africa; the forest and savannah elephants of West Africa; and (iii) the savannah elephants of eastern, southern and Central Africa. We propose that the complex phylogeographic patterns we detect in African elephants result from repeated continental-scale climatic changes over their five-to-six million year evolutionary history. Until there is consensus on the taxonomy, we suggest that the genetic and ecological distinctness of these lineages should be an important factor in conservation management planning.     

Genetic relatedness and disrupted social structure in a poached population of African elephants

We use genetic measures of relatedness and observations of female bonding to examine the demographic signature of historically heavy poaching of a population of free-ranging African elephants. We collected dung samples to obtain DNA and observed behaviour from 102 elephant families over a 25-month period in 2003–2005 in Mikumi National Park, Tanzania. Poaching reduced the population by 75% in the decade prior to the 1989 ivory trade ban; park records indicate that poaching dropped significantly in Mikumi following the ban. Using 10 microsatellite loci, DNA was genotyped in 203 elephants and pair-wise relatedness was calculated among adult females within and between groups. The Mikumi population is characterized by small group size, considerable variation in group relatedness, females with no first-order adult relatives and females that form only weak social bonds. We used gene-drop analysis and a model of a genetically intact pedigree to compare our observed Mikumi group relatedness to a simulated genetically intact unpoached expectation. The majority of groups in Mikumi contain 2 to 3 adults; of these, 45% were classified as genetically disrupted. Bonding, quantified with a pair-wise association index, was significantly correlated with relatedness; however only half of the females formed strong bonds with other females, and relatedness was substantially lower for a given bond strength as compared to an unpoached population. Female African elephants without kin demonstrated considerable behavioural plasticity in this disturbed environment, grouping with other females lacking kin, with established groups, or remaining alone, unable to form any stable adult female-bonds. We interpret these findings as the remaining effect of poaching disturbance in Mikumi, despite a drop in the level of poaching since the commercial trade in ivory was banned 15 years ago.     

Seasonality in elephant dung decay and implications for censusing and population monitoring in south-western Cameroon

Dung decay rates have been used in the past to correct elephant dung counts to estimates of population numbers. These assume that the dung is in a ‘steady state’ where production rates are equal to disappearance rates. The inter‐seasonal variation in decay rates, however, has never been fully investigated for elephant dung. This study, in the Banyang‐Mbo Wildlife Sanctuary in SW Cameroon, investigated whether a single dung decay rate is really appropriate when converting dung counts to population density estimates. A total of 870 fresh elephant dung‐piles were monitored until they had completely decayed, with at least 60 fresh dung piles located each month of the year between July 1994 to June 1995. The elephant dung decay rate obtained was 55.6% to 66.7% lower than those obtained for the rainforests of Gabon. This has implications for using decay rates obtained elsewhere to compute elephant densities from dung counts. Statistically significant differences were found in the mean duration of dung‐piles between different months and different seasons. Environmental variables, with the exception of rainfall, did not aid in predicting the duration of elephant dung‐piles. The model of Plumptre & Harris was used to estimate the standing crop of dung at any particular time of the year. The results show that, if there was no emigration of elephants from the population, then there was only a three‐month period when the dung was in a ‘steady state’. If emigration occurred during the wet season as is thought to occur then there was no period of ‘steady state’.     

A landscape-level assessment of Asian elephant habitat,its population and elephant–human conflict in the Anamalai hill ranges of southern Western Ghats,India

Spatial information at the landscape scale is extremely important for conservation planning, especially in the case of long-ranging vertebrates. The biodiversity-rich Anamalai hill ranges in the Western Ghats of southern India hold a viable population for the long-term conservation of the Asian elephant. Through rapid but extensive field surveys we mapped elephant habitat, corridors, vegetation and land-use patterns, estimated the elephant population density and structure, and assessed elephant–human conflict across this landscape. GIS and remote sensing analyses indicate that elephants are distributed among three blocks over a total area of about 4600 km². Approximately 92% remains contiguous because of four corridors; however, under 4000 km² of this area may be effectively used by elephants. Nine landscape elements were identified, including five natural vegetation types, of which tropical moist deciduous forest is dominant. Population density assessed through the dung count method using line transects covering 275 km of walk across the effective elephant habitat of the landscape yielded a mean density of 1.1 (95% CI = 0.99–1.2) elephant/km². Population structure from direct sighting of elephants showed that adult male elephants constitute just 2.9% and adult females 42.3% of the population with the rest being sub-adults (27.4%), juveniles (16%) and calves (11.4%). Sex ratios show an increasing skew toward females from juvenile (1:1.8) to sub-adult (1:2.4) and adult (1:14.7) indicating higher mortality of sub-adult and adult males that is most likely due to historical poaching for ivory. A rapid questionnaire survey and secondary data on elephant–human conflict from forest department records reveals that villages in and around the forest divisions on the eastern side of landscape experience higher levels of elephant–human conflict than those on the western side; this seems to relate to a greater degree of habitat fragmentation and percentage farmers cultivating annual crops in the east. We provide several recommendations that could help maintain population viability and reduce elephant–human conflict of the Anamalai elephant landscape.     

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.

     

Sex and size related differences in the dry season feeding patterns of elephants in Chobe National Park, Botswana

Differences in feeding patterns of the African elephant were examined by sex and age during the dry season in a dystrophic savanna-woodland ecosystem in northern Botswana. Adult males had the least diverse diet in terms of woody plant species, but they consumed more plant parts than family units. The diameter of stems of food plants broken or bitten off was also greater for adult males than for females and subadult males. Adult males spent more time foraging on each woody plant than did females. The number of woody plant species and individuals present were higher at feeding sites of family units than at feeding sites of adult males, indicating that family units positioned themselves at feeding sites with higher species diversity than those of males. We argue that the most likely explanation for these differences is related to the pronounced sexual size dimorphism exhibited by elephants, resulting in sex differences in browsing patterns due to the allometric relationships that govern the tolerance of herbivores for variation in diet quality. From our results this Body Size Hypothesis is accepted rather than the alternative Scramble Competition Hypothesis, which predicts that adult male elephants consume lower quality browse because they are displaced from preferred browse as an outcome of scramble competition with adult females and their offspring. If the feeding patterns of adult male elephants were affected by intersexual scramble competition, we would expect adult males to browse at a higher level in the canopy than the smaller-bodied females and their offspring. No evidence was found for this, although adult females were found to browse at a higher level in the canopy when feeding in close proximity to subadults and juveniles than when feeding alone. Sex differences in elephant browsing patterns are, we propose, of relevance to understanding and managing elephant impacts on African woodlands.     

Feeding patterns of elephants at the Atherstone Collaborative Nature Reserve

The African savannah elephant (Loxodonta africana Blumenbach) is a generalist herbivore that relies on widely distributed resources. Vegetation decline, aggravated by these elephants, can compromise local conservation efforts. Thus it imperative to understand the factors that drive them to consume specific plant species and plant parts. The objective of our study was to investigate the feeding patterns of African savannah elephants in the enclosed bushveld savannah at the Atherstone Collaborative Nature Reserve in South Africa. For 1 year, we examined elephant selection of woody versus herbaceous vegetation, and identified which plant species and parts were preferentially consumed. We accomplished this by directly observing feeding elephants, and by utilizing data collected on elephant footprints, dung piles, stripped bark and broken branches. We further conducted vegetation surveys to determine selection frequency relative to species abundance. Elephants showed a preference for different plant parts consumption in the feeding plots. In total, leaves, branches and bark contributed mostly to their diet. Seasonal selection patterns showed an increasing proportion of bark and branch consumption during the dry season.     

Genetic diversity, social structure, and conservation value of the elephants of the Nakai Plateau, Lao PDR, based on non-invasive sampling

The Lao People??s Democratic Republic (PDR) may have the largest Asian elephant population in Indochina. However, elephants on Lao PDR??s Nakai Plateau are potentially threatened by the construction of a hydropower dam that will flood important habitat. We conducted a non-invasive genetic study of elephants in this region to provide baseline data on genetic diversity and social structure prior to dam construction. For the 102 elephants we detected, values of observed heterozygosity (0.711) and allelic diversity (8.0 alleles/locus) at microsatellite loci were higher than those found in elephant populations in India and Vietnam, while mitochondrial diversity (haplotype diversity 0.741; nucleotide diversity 0.011) was similar to that reported for the Lao/Vietnam region. Six mitochondrial haplotypes were detected, representing both major clades previously reported in this species. Relatedness estimates between females and young detected near each other are consistent with familial relationships, and relatedness estimates between adult males and females suggest male locational dispersal. Since family group structure appears to be intact in the Nakai region, these elephants will likely move as relatively large family groups in response to habitat disturbance. These results have positive implications for the viability of the elephant population in this region, demonstrate its conservation significance, and will be valuable for predicting and monitoring the effects of the hydropower dam over time.     

Fine‐scale group structure and demography of African savanna elephants recolonizing lands outside protected areas

Aim Dispersal is a critical component of animal ecology that is poorly understood for most species. In particular, savanna elephants (Loxodonta africana) have been studied for decades in national parks across Africa, but little is known about their dispersal into new or unused habitats or their population dynamics in human‐dominated landscapes. We capitalized on a natural dispersal event of savanna elephants recolonizing communal land in southern Kenya to document their demographic characteristics and genetic relationships. Location Rift Valley province of Kenya. Methods We collected faecal samples and used genetic methods to identify individuals, estimate the sex ratio and evaluate the patterns of relatedness within the female groups and male aggregations. We also measured dung bolus circumference to assign age classes to individuals and estimate the age structure. Results We identified 112 individuals with a sex ratio not different from one (1.32:1.00). The age structure was skewed towards younger elephants (71%), suggesting the potential for rapid growth from reproduction. We detected significantly higher kinship levels within female groups (R = 0.124 ± 0.023), suggesting that family groups colonized the site, but found little support for higher‐order genetic relationships among female groups. Males detected together were unrelated (R = 0.003 ± 0.030). Main conclusions Our results suggest that highly social mammals, such as savanna elephants, disperse into unoccupied habitat as family groups and that a young demographic structure and a large number of males might be expected in establishing populations. These findings highlight the potential value of indirect, non‐invasive methods for assessing elephant herd and demographic characteristics when direct observations are difficult.     

Diet and distribution of elephant in the Maputo Elephant Reserve, Mozambique

The distribution and diet of the elephants of the Maputo Elephant Reserve were studied using dung counts, satellite tracking and faecal analysis. The results were compared with earlier data from before the civil war in Mozambique. The elephant population decreased during the civil war, but 180 animals still remain. Earlier studies described the elephants as preferring the grass plains. Currently, the elephants prefer the dense forest patches over the high quality forage found in the grass plains. Water salinity affected distribution; elephant dung piles were found closer to fresh water in the dry season. A total of 95 different plant species were identified in the faeces. The percentage of grass was relatively low compared with other studies, increasing at the beginning of the rainy season. At the end of the dry season, elephants concentrated on the few available browse species with young leaves, but generally preferred grass species to browse species. Diet composition was mainly affected by season and less by habitat. The elephants have changed their habitat preference in reaction to poaching, and probably increased the contribution of browse species in the diet. The presence of forest patches has been vital for the survival of the elephants.     

Observations of immature and adult stages of the myrmecophilous cetoniine beetle Campsiura nigripennis (Coleoptera: Scarabaeidae)

Several cetoniine species are known or speculated to be associated with ants, based on their specialized morphological characters. However, there are only a few species where biological information on the larval and adult stages is available. Field observations revealed that Campsiura nigripennis spends the immature stages inside elephant dung, and that adult females fly to elephant dung for oviposition. In addition, adult beetles of C. nigripennis intruded into arboreal nests of Oecophylla smaragdina. Specialized morphological characters appear to allow them to tolerate attacks from the ants. Furthermore, the distribution of the beetle in continental Asia largely overlaps that of the Asian elephant, indicating that dung of elephants, in conjunction with that of other large mammals, is fundamental to the biology of C. nigripennis.     

Forest Elephants: Tree Planters of the Congo

The abundance of large vertebrates is rapidly declining, particularly in the tropics where over-hunting has left many forests structurally intact but devoid of large animals. An urgent question then, is whether these 'empty' forests can sustain their biodiversity without large vertebrates. Here we examine the role of forest elephant ( Loxodonta africana cyclotis ) seed dispersal in maintaining the community structure of trees in the Ndoki Forest, northern Congo. Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. Our analysis of the spatial distribution of trees from a sample of 5667 individuals showed that dispersal mechanism was tightly correlated with the scale of spatial aggregation. Increasing amounts of elephant seed dispersal was associated with decreasing aggregation. At distances of<200 m, trees whose seeds are dispersed only by elephants were less aggregated than the random expectation, suggesting Janzen–Connell effects on seed/seedling mortality. At the landscape scale, seed dispersal mode predicted the rate at which local tree community similarity decayed in space. Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees.     

Contribution of molecular phylogeny and morphometrics to the systematics of African elephants

African elephants are conventionally classified as a single species: Loxodonta africana (Blumenbach 1797). However, the discovery in 1900 of a smaller form of the African elephant, spread throughout the equatorial belt of this land, has given rise to a debate over the relevance of a second species of elephant in Africa. The twentieth century has not provided any definite answer to this question. Actually, recent molecular analyses have sustained this issue by advocating either a division of forest elephants into a valid species, or their inclusion as a subspecies of L. africana. Our work initiated at the National Museum of Natural History of Paris provides new molecular (mitochondrial) and morphological (and morphometrical) evidence making it possible to propose a comprehensive phylogenetic hypothesis. It appears that there is no conclusive argument to keep forest elephants (cyclotis form) and savannah elephants (africana form) apart in two distinct species. A high level of mitochondrial introgression between the two forms, as well as a continuum in the morphology of the skulls of the two morphotypes rather suggests that, despite an ancient division, these two taxa freely interbreed wherever their ranges intersect. We thus adopt a conservative systematic position in considering these two forms as two subspecies, respectively: L. africana africana, the savannah elephant, and L. africana cyclotis, the forest elephant. We finally discuss the conservation topic in the light of this systematic framework.     

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.