The movement of African elephants in a human-dominated land-use mosaic

Land outside of gazetted protected areas is increasingly seen as important to the future of elephant persistence in Africa. However, other than inferential studies on crop raiding, very little is understood about how elephants Loxodonta africana use and are affected by human-occupied landscapes. This is largely a result of restrictions in technology, which made detailed assessments of elephant movement outside of protected areas challenging. Recent advances in radio telemetry have changed this, enabling researchers to establish over a 24-h period where tagged animals spend their time. We assessed the movement of 13 elephants outside of gazetted protected areas across a range of land-use types on the Laikipia plateau in north-central Kenya. The elephants monitored spent more time at night than during the day in areas under land use that presented a risk of mortality associated with human occupants. The opposite pattern was found on large-scale ranches where elephants were tolerated. Furthermore, speed of movement was found to be higher where elephants were at risk. These results demonstrate that elephants facultatively alter their behaviour to avoid risk in human-dominated landscapes. This helps them to maintain connectivity between habitat refugia in fragmented land-use mosaics, possibly alleviating some of the potential negative impacts of fragmentation. At the same time, however, it allows elephants to penetrate smallholder farmland to raid crops. The greater the amount of smallholder land within an elephant's range, the more it was utilized, with consequent implications for conflict. These findings underscore the importance of (1) land-use planning to maintain refugia; (2) incentives to prevent further habitat fragmentation; (3) the testing and application of conflict mitigation measures where fragmentation has already taken place.     

The conflict between humans and elephants in the central African forests

Elephants and humans each suffer from the presence of the other when they occupy the same forests. Farmers risk losing their crops to elephants, while elephants are displaced by settlements, agriculture, roads and development projects. Elephants have also been hunted for ivory. The ivory trade in the equatorial forests expanded in the nineteenth century as Europe prospered, and then again in the twentieth century as the Far East prospered. Forest elephant numbers were depleted each time.
Elephants are unpopular in the forest zone, and increasing human populations combined with the spread of democracy in central Africa pose a major threat to their future. If elephants are to be tolerated by villagers living in the equatorial forests, the costs they impose must be reduced and the benefits to the rural populace must be increased. A three-pronged strategy is suggested, involving land-use planning, measures to mitigate crop damage, and programmes to enhance the value of elephants. Elephants could be viewed as assets if their importance in the forest ecosystem were recognized, if they were domesticated for logging or transport, or if their presence was one of the factors which attracted tourists to the forest zone. However, management strategies based on hunting have the best chance of conserving elephants because of the importance of hunting in the culture of the forest people. Sport hunting for trophies may bring the greatest revenues. Community wildlife-management programmes, where village councils make the decisions, could prevent overexploitation. There are no simple answers, however, because one form of management may conflict with the goals of another.     

The use of an internal representation in fast goal-directed movements: a modelling approach

This study investigates the role of the human central nervous system (CNS) in the control of fast goaldirected movements. The main problem is that the latencies inherent in the transmission of physiological signals cause a delayed feedback of sensory information. Therefore, the muscle command signals cannot be explained by a simple servo-loop, so a more sophisticated control structure is required. Our hypothesis is that the CNS employs an internal representation of the controlled system in order to circumvent the drawbacks of the physiological loop delay. To test this hypothesis a mathematical model based on an internal representation and an internal state feedback has been developed. Computer simulations of double-step stimuli (control behaviour), tendon vibration and torque disturbances (disturbance behaviour) and load perturbations (adaptation behaviour) proved to agree remarkably well with experimental observations. The proposed control model can explain the open-loop and closed-loop aspects of human motor control. Hence, the use of an internal representation in generating the muscle command signals is very plausible.     

The use of modelling and simulation approach in reconstructing past landscapes from fossil pollen data: a review and results from the POLLANDCAL network

Information on past land cover in terms of absolute areas of different landscape units (forest, open land, pasture land, cultivated land, etc.) at local to regional scales is needed to test hypotheses and answer questions related to climate change (e.g. feedbacks effects of land-cover change), archaeological research, and nature conservancy (e.g. management strategy). The palaeoecological technique best suited to achieve quantitative reconstruction of past vegetation is pollen analysis. A simulation approach developed by Sugita (the computer model POLLSCAPE) which uses models based on the theory of pollen analysis is presented together with examples of application. POLLSCAPE has been adopted as the central tool for POLLANDCAL (POLlen/LANdscape CALibration), an international research network focusing on this topic. The theory behind models of the pollen–vegetation relationship and POLLSCAPE is reviewed. The two model outputs which receive greatest attention in this paper are the relevant source area of pollen (RSAP) and pollen loading in mires and lakes. Six examples of application of POLLSCAPE are presented, each of which explores a possible use of the POLLANDCAL tools and a means of validating or evaluating the models with empirical data. The landscape and vegetation factors influencing the size of the RSAP, the importance of pollen productivity estimates (PPEs) for the model outputs, the detection of small and rare patches of plant taxa in pollen records, and quantitative reconstructions of past vegetation and landscapes are discussed on the basis of these examples. The simulation approach is seen to be useful both for exploring different vegetation/landscape scenarios and for refuting hypotheses.     

Nocturnal behavior in a group of female African elephants

The nocturnal behavior of a stable group of female, African elephants (Loxodonta africana africana) was studied to: (1) examine their behavior as a function of hour of night; (2) qualitatively compare the elephants' activity budgets to those reported in a previous study; and (3) document the presence of aggressive and stereotypic behaviors that might necessitate a change in their management. The elephants were systematically observed at least five times per week for 10 weeks between 17:00 and 08:00. Instantaneous focal samples of behavior, location, and proximity were taken every minute on a rotating basis, and all observed occurrences of social behavior were recorded. The hour of night affected elephant activity: significant relationships were found between hour of night and percent of time they spent feeding, lying, and standing. The overall activity budgets of the elephants were similar to the activity budgets reported in a previous study, although differences were evident in lying, stereotypic, and social behaviors. These differences might be a function of age. Affiliative behaviors accounted for 57% of the elephants' social behaviors, and agonistic behaviors among the elephants occurred infrequently and caused no injuries. Additionally, the elephants used all areas to which they had access. These findings provide compelling evidence that unrestricted social access during the night is the appropriate management strategy for these elephants. The results from the present study also highlight the importance of replicating existing studies and using multiple behavioral measures to make decisions regarding the welfare and management of stable groups of captive elephants. Zoo Biol 25:173–186, 2006. © 2006 Wiley‐Liss, Inc.     

Global trends and factors associated with the illegal killing of elephants: A hierarchical bayesian analysis of carcass encounter data

Elephant poaching and the ivory trade remain high on the agenda at meetings of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Well-informed debates require robust estimates of trends, the spatial distribution of poaching, and drivers of poaching. We present an analysis of trends and drivers of an indicator of elephant poaching of all elephant species. The site-based monitoring system known as Monitoring the Illegal Killing of Elephants (MIKE), set up by the 10(th) Conference of the Parties of CITES in 1997, produces carcass encounter data reported mainly by anti-poaching patrols. Data analyzed were site by year totals of 6,337 carcasses from 66 sites in Africa and Asia from 2002-2009. Analysis of these observational data is a serious challenge to traditional statistical methods because of the opportunistic and non-random nature of patrols, and the heterogeneity across sites. Adopting a bayesian hierarchical modeling approach, we used the proportion of carcasses that were illegally killed (PIKE) as a poaching index, to estimate the trend and the effects of site- and country-level factors associated with poaching. Important drivers of illegal killing that emerged at country level were poor governance and low levels of human development, and at site level, forest cover and area of the site in regions where human population density is low. After a drop from 2002, PIKE remained fairly constant from 2003 until 2006, after which it increased until 2008. The results for 2009 indicate a decline. Sites with PIKE ranging from the lowest to the highest were identified. The results of the analysis provide a sound information base for scientific evidence-based decision making in the CITES process.     

A case study of apparent conflict between molecular phylogenies: the interrelationships of African elephants

Recent molecular phylogenies of the African elephants suggest that there is an evolutionary structure within Loxodonta africana. Some nuclear results ( Roca et al., 2001 ) support the separation of the forest African elephant subspecies L. a. cyclotis as a species distinct from the savannah elephant L. a. africana, on the basis of the recognition of both forming highly divergent (reciprocally monophyletic) clades. Conversely, a mitochondrial survey ( Eggert et al., 2002 ), while admitting a geographic partitioning of the genetic structure within African elephants, suggests retaining the status quo. They recognize three diagnosible entities (western, central and south‐eastern Africa) with non‐overlapping ranges within L. africana sensu lato. In order to address these conflicting views (historical fragmentation and speciation or isolation by distance, respectively), we have sequenced two datasets of 1961 bp (for 50 elephants) and about 3700 bp, respectively (for 20 elephants) of the mitochondrial DNA for both forms of elephants (cyclotis and africana). They span the cytochrome b gene, the control region and several RNAs. When compared with former mtDNA data, they provide the most comprehensive view of the African elephant phylogeny (78 mtDNA haplotypes, of which 44 are new) and provide the first insight into populations from the Democratic Republic of Congo. The genetic diversity of mtDNA was appraised and the stability of alternative phylogenetic trees was investigated. Our results are inconsistent with both those prior studies. They revealed two highly divergent molecular clades referred to as F and S, that do not conform to the morphological delineations of cyclotis and africana. A non‐negligible proportion of specimens of L. a. africana display haplotypes prevailing in forest elephant populations (clade F). The geographic distribution of clades and areas of their co‐occurrence support the hypothesis of incomplete isolation between forest and savannah African elephant populations, followed by recurrent interbreeding between the two forms. We state that the conclusions of prior studies resulted from insufficient character and/or geographic sampling. We conclude that there is no satisfying argument which can recognize two or more species of African elephants. We briefly comment on the meaning of such an attitude in a conservation viewpoint. © The Willi Hennig Society 2005.     

Nocturnal behavior in a group of unchained female African elephants

The chaining of elephants at night is a common management strategy in zoos, yet the costs and benefits of such a strategy are relatively unknown. A study of three unchained female African elephants was undertaken to document their nocturnal behavior. The subjects were observed between the hours of 1800 and 0800 for 10 weeks in the summer of 1992 (total of 172 hr) and 14 weeks in the summer of 1994 (total of 153 hr). Scan data were collected every 5 min to gather information on activity budgets, social proximity, and space utilization. All‐occurrence data were collected on social and non‐social behaviors. In each year of the study, the subjects spent equivalent amounts of time eating, lying, standing, and walking. Additionally, subjects spent half of their time within one body length of another animal and utilized all three available enclosures. Social and non‐social behaviors were frequent, and these data plus the activity profiles reveal the animals generally were most active between the hours of 1800 and 2400 and 0600 and 0700. The findings suggest that the use of no restraints is currently an effective strategy for this elephant group. The high activity levels observed during many of the early evening hours suggest that zoos could permit increased activity and social interactions by extending the hours when the elephants are unchained. Zoo Biol 18:101–109, 1999. © 1999 Wiley‐Liss, Inc.     

Phenotype matching and inbreeding avoidance in African elephants

Perhaps the most important 'decision' made by any animal (or plant) is whether to disperse--leave kith and kin, or remain with the familiar and related. The benefits of staying at home are obvious, so dispersal requires an explanation--and the most popular is that dispersal functions to avoid inbreeding depression. Strong support comes from the observation that dispersal is so often sex biased. Simply put, all else being equal members of both sexes should prefer to remain philopatric, but this would lead to inbreeding depression so members of one sex have to disperse. In principle, this link between inbreeding depression and sex-biased dispersal could be broken if individuals recognize close kin and avoid mating with them. Archie et al. (2007) provide one of the most compelling analyses to date of the interaction among inbreeding avoidance, kin recognition and mating strategies in any mammal, clearly showing that elephants recognize even close paternal kin and avoid mating with them. Their important results illuminate the subtleties of elephant inbreeding avoidance as well as illustrate the difficulty of arriving at definitive answers to questions about the evolution of dispersal behaviour.     

The spatial scaling of habitat selection by African elephants

1. Understanding and accurately predicting the spatial patterns of habitat use by organisms is important for ecological research, biodiversity conservation and ecosystem management. However, this understanding is complicated by the effects of spatial scale, because the scale of analysis affects the quantification of species-environment relationships. 2. We therefore assessed the influence of environmental context (i.e. the characteristics of the landscape surrounding a site), varied over a large range of scales (i.e. ambit radii around focal sites), on the analysis and prediction of habitat selection by African elephants in Kruger National Park, South Africa. 3. We focused on the spatial scaling of the elephants' response to their main resources, forage and water, and found that the quantification of habitat selection strongly depended on the scales at which environmental context was considered. Moreover, the inclusion of environmental context at characteristic scales (i.e. those at which habitat selectivity was maximized) increased the predictive capacity of habitat suitability models. 4. The elephants responded to their environment in a scale-dependent and perhaps hierarchical manner, with forage characteristics driving habitat selection at coarse spatial scales, and surface water at fine spatial scales. 5. Furthermore, the elephants exhibited sexual habitat segregation, mainly in relation to vegetation characteristics. Male elephants preferred areas with high tree cover and low herbaceous biomass, whereas this pattern was reversed for female elephants. 6. We show that the spatial distribution of elephants can be better understood and predicted when scale-dependent species-environment relationships are explicitly considered. This demonstrates the importance of considering the influence of spatial scale on the analysis of spatial patterning in ecological phenomena.     

A preliminary study of the behavioral effects of feeding enrichment on African elephants

Although commonly practiced with many species, feeding enrichment in elephants is understudied. The behavioral effects of feeding enrichment were tested in three African elephants by substituting an equal dry weight of browse for hay in an ABA design. The results showed a significant increase in feeding and significant decreases in drinking and inactivity when the browse was present. Additionally, changes in feeding, inactivity, and time spent in contact were observed outside the time the browse was actually presented, although the relationship of these changes to the experimental methodology is unknown. A significant increase in visibility to zoo visitors during the browse conditions demonstrates that browse is an effective, naturalistic method for increasing visibility as well as species-typical behaviors. Managers of captive elephants should consult with a nutritionist to address issues of energetics, nutritional content, and secondary compounds when using browse as feeding enrichment. Zoo Biol 19:485-493, 2000. Copyright 2000 Wiley-Liss, Inc.     

Fish telemetry in African inland waters and its use in management: a review

Reviews in Fish Biology and Fisheries - Fish telemetry is a widely established technique in developed countries. However, in underdeveloped regions, its use is generally lacking. We briefly present...     

Age- and tactic-related paternity success in male African elephants

Information on age- and tactic-related paternity success isessential for understanding the lifetime reproductive strategyof males and constitutes an important component of the fitnesstrade-offs that shape the life-history traits of a species.The degree of reproductive skew impacts the genetic structureof a population and should be considered when developing conservationstrategies for threatened species. The behavior and geneticstructure of species with large reproductive skew may be disproportionatelyimpacted by anthropogenic actions affecting reproductively dominantindividuals. Our results on age- and tactic-specific paternitysuccess in male African elephants are the first from a free-rangingpopulation and demonstrate that paternity success increasesdramatically with age, with the small number of older bullsin the competitive state of musth being the most successfulsires. However, nonmusth males sired 20% of genotyped calves,and 60% of mature bulls (>20 years old) were estimated tohave sired offspring during the 5-year study period. The 3 mostsuccessful males sired less than 20% of the genotyped offspring.Hence, contrary to prediction from behavior and life-historytraits, reproduction was not heavily skewed compared with manyother mammalian systems with a similar breeding system. Nevertheless,these results indicate that trophy hunting and ivory poaching,both of which target older bulls, may have substantial behavioraland genetic effects on elephant populations. In addition, theseresults are critical to the current debate on methods for managingand controlling increasing populations of this species.     

The Knysna elephants: a population study conducted using faecal DNA

The elephants of the Knysna region continue to survive, despite fears that there was only a single surviving female. Their range is larger than previously believed, and includes the Afromontane forest and mountain fynbos. The five individuals detected in this study were all females, and share a single mitochondrial DNA control region haplotype with individuals from Addo Elephant National Park. At least two of these elephants appear to be first‐order relatives, and the others may be part of a single matrilineal group. The genetic diversity detected is lower than that found in most African savanna populations, but is higher than that found at Addo, where individuals represent the descendents of a severe population size bottleneck. Levels of genetic diversity are more similar to those detected at Kruger National Park, suggesting that the Knysna elephants represent a remnant of the once widespread populations of South Africa.     

Growth and age determination of African savanna elephants

Understanding the population dynamics of savanna elephants depends on estimating population parameters such as the age at first reproduction, calving interval and age-specific survival rates. The generation of these parameters, however, relies on the ability to accurately determine the age of individuals, but a reliable age estimation technique for free-ranging elephants is presently not available. Shoulder heights of elephants were measured in 10 populations in five countries across southern and eastern Africa. Data included shoulder height measurements from two populations where the age of each individual was known (i.e. Addo Elephant National Park, South Africa and Amboseli National Park, Kenya). From the known-age data, Von Bertalanffy growth functions were constructed for both male and female elephants. Savanna elephants were found to attain similar asymptotic shoulder heights in the 10 populations, while individuals in the two known-age populations grew at the same rate. The Von Bertalanffy growth curves allowed for the accurate age estimation of females up to 15 years of age and males up to 36 years of age. The results indicate that shoulder height can serve as an indicator of chronological age for elephants below 15 years of age for females and 36 years of age for males. Ages derived from these growth curves can then be used to generate age-specific population variables, which will help assess the demographic status of savanna elephant populations across Africa.     

Chemosignalling of musth by individual wild African elephants (Loxodonta africana): implications for conservation and management

Elephants have extraordinary olfactory receptive equipment, yet this sensory system has been only minimally investigated in wild elephants. We present an in-depth study of urinary chemical signals emitted by individual, behaviourally characterized, wild male African elephants, investigating whether these compounds were the same, accentuated, or diminished in comparison with captive individuals. Remarkably, most emitted chemicals were similar in captive and wild elephants with an exception traced to drought-induced dietary cyanates among wild males. We observed developmental changes predominated by the transition from acids and esters emitted by young males to alcohols and ketones released by older males. We determined that the ketones (2-butanone, acetone and 2-pentanone, and 2-nonanone) were considerably elevated during early musth, musth and late musth, respectively, suggesting that males communicate their condition via these compounds. The similarity to compounds released during musth by Asian male elephants that evoke conspecific bioresponses suggests the existence of species-free 'musth' signals. Our innovative techniques, which allow the recognition of precise sexual and musth states of individual elephants, can be helpful to managers of both wild and captive elephants. Such sampling may allow the more accurate categorization of the social and reproductive status of individual male elephants.     

Humans and elephants as treefall drivers in African savannas

Humans have played a major role in altering savanna structure and function, and growing land‐use pressure will only increase their influence on woody cover. Yet humans are often overlooked as ecological components. Both humans and the African elephant Loxodonta africana alter woody vegetation in savannas through removal of large trees and activities that may increase shrub cover. Interactive effects of both humans and elephants with fire may also alter vegetation structure and composition. Here we capitalize on a macroscale experimental opportunity – brought about by the juxtaposition of an elephant‐mediated landscape, human‐utilized communal harvesting lands and a nature reserve fenced off from both humans and elephants – to investigate the influence of humans and elephants on height‐specific treefall dynamics. We surveyed 6812 ha using repeat, airborne high resolution Light Detection and Ranging (LiDAR) to track the fate of 453 685 tree canopies over two years. Human‐mediated biennial treefall rates were 2–3.5 fold higher than the background treefall rate of 1.5% treefall ha^–1, while elephant‐mediated treefall rates were 5 times higher at 7.6% treefall ha^–1 than the control site. Model predictors of treefall revealed that human or elephant presence was the most important variable, followed by the interaction between geology and fire frequency. Treefall patterns were spatially heterogeneous with elephant‐driven treefall associated with geology and surface water, while human patterns were related to perceived ease of access to wood harvesting areas and settlement expansion. Our results show humans and elephants utilize all height classes of woody vegetation, and that large tree shortages in a heavily utilized communal land has transferred treefall occurrence to shorter vegetation. Elephant‐ and human‐dominated landscapes are tied to interactive effects that may hinder tree seedling survival which, combined with tree loss in the landscape, may compromise woodland sustainability.     

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.