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.     

Perceived human–elephant conflict and its impact for elephant conservation in northern Congo

Human–elephant conflict is a common conservation problem throughout Africa, but poorly studied where forest elephants (Loxodonta cyclotis) occur. Here, we investigated people's perceptions towards the impact of elephants around Nouabalé‐Ndoki National Park, northern Congo. We aimed to understand the perceptual differences amongst residents of four villages that varied substantially in the degree of conservation benefits received. We used a multivariate analysis to investigate how socio‐economic variables, such as employment, wealth, education and ethnicity, influenced perceptions. Using both quantitative and qualitative data, we found that the majority of respondents experienced elephant impacts, mainly through crop raiding. Residents of the village where the local conservation project is based had significantly more positive perceptions of elephants, whereas perceptions of farmers were mostly negative. We identified some misunderstandings regarding the responsibilities of elephant impact mitigation regarding benefit sharing, stakeholder involvement and lawbreaking, but also willingness to apply mitigation measures. To mitigate the prevalent impact of elephants, a comprehensive approach of measuring impact, exploring community‐based mitigating strategies and understanding of the root causes of the conflict is crucial. We propose a long‐term programme within logging concessions organizing groups of farmers to cooperate on mitigation techniques and explore alternative incomes.     

Linking two elephant refuges with a corridor in the communal lands of Zimbabwe

Wildlife corridors, protected bands of suitable habitat linking core populations of plants and animals, are seen as the best solution to the problem of habitat fragmentation. A corridor between two wildlife refuges was identified in the communal lands of Zimbabwe. Results of tracking the current preferred migration of bull elephants between the two refuges using radio collars were combined with a GIS analysis to examine the zone where conservation of habitat would have least impact on current activities within the communal lands. A suitable corridor was identified using least‐cost analysis allowing for the improved conservation of the elephants and therefore potentially increasing the benefits to local residents by both reducing human/elephant conflict and increasing income from sport hunting and tourism in the region. Recent political violence in the corridor region, the illegal killing of elephants and the loss of suitable habitat makes the implementation of this corridor unlikely.     

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.     

Beehive fence deters crop-raiding elephants

Previous work has shown that African elephants Loxodonta africana will avoid African honeybees Apis mellifera scutellata . Here we present results from a pilot study conducted to evaluate the concept of using beehives to mitigate elephant crop depredation. In Laikipia, Kenya, we deployed a 90-m fence-line of nine inter-connected hives, all empty, on two exposed sides of a square two-acre farm that was experiencing high levels of elephant crop depredation. Compared with a nearby control farm of similar status and size, our experimental farm experienced fewer raids and consequently had higher productivity. Socioeconomic indicators suggest that not only was the concept of a beehive fence popular and desired by the community but also that it can pay for its construction costs through the sale of honey and bee products. We are calling for experiments testing this concept of a 'guardian beehive-fence' to be conducted rigorously and scientifically in as wide a range of agricultural settings as possible to evaluate jointly its effectiveness and efficiency.     

Beehive fences as effective deterrents for crop‐raiding elephants: field trials in northern Kenya

Increasing elephant populations in Kenya since 1989 have been widely praised as a conservation success story. However, where elephants and agricultural land overlap, incidents of human–elephant conflict are on the increase. Wildlife managers and farmers are now trying different farm‐based deterrents to keep elephants out of crops. Here, we present data on the effectiveness of a novel beehive fence deployed in a Turkana community of 62 communally run farms in Kenya. Specifically, 1700 m of beehive fences semi‐surrounded the outer boundaries of seventeen farms, and we compared elephant farm invasion events with these and to seventeen neighbouring farms whose boundaries were ‘protected’ only by thorn bush barriers. We present data from 45 farm invasions, or attempted invasions, recorded over 2 years. Thirteen groups of elephants approached the beehive fences and turned away. Of the 32 successful farm invasions, only one bull elephant broke through the beehive fences. These results demonstrate that beehive fences are more effective than thorn bush barriers at deterring elephants and may have a role to play in alleviating farmer–elephant conflict. Additionally, the harvesting of 106 kg of honey during the trial period suggests that beehive fences may also improve crop production and enhance rural livelihoods through honey sales.     

圈养雌性非洲象妊娠期尿中性激素水平的变化

非洲象(Loxodonta africana)属于哺乳纲、长鼻目、象科、非洲象属,主要分布于非洲东部、中部、西部、西南部和东南部等广大地区,目前在世界大部分地区都有人工圈养.非洲象没有固定的发情季节,常年均可交配繁殖,雌兽的怀孕期为21 ～23个月,略长于亚洲象,是哺乳动物中孕期最长的动物.     

Initial findings on visual acuity thresholds in an African elephant (Loxodonta africana)

There are only a few published examinations of elephant visual acuity. All involved Asian elephants (Elephas maximus) and found visual acuity to be between 8′ and 11′ of arc for a stimulus near the tip of the trunk, equivalent to a 0.50 cm gap, at a distance of about 2 m from the eyes. We predicted that African elephants (Loxodonta africana) would have similarly high visual acuity, necessary to facilitate eye‐trunk coordination for feeding, drinking and social interactions. When tested on a discrimination task using Landolt‐C stimuli, one African elephant cow demonstrated a visual acuity of 48′ of arc. This represents the ability to discriminate a gap as small as 2.75 cm in a stimulus 196 cm from the eye. This single‐subject study provides a preliminary estimate of the visual acuity of African elephants. Zoo Biol 29:30–35, 2010. © 2009 Wiley‐Liss, Inc.     

Effects of human–carnivore conflict on tiger (Panthera tigris) and prey populations in Lao PDR

Unique to South-east Asia, Lao People's Democratic Republic contains extensive habitat for tigers and their prey within a multiple-use protected area system covering 13% of the country. Although human population density is the lowest in the region, the impact of human occurrence in protected areas on tiger Panthera tigris and prey populations was unknown. We examined the effects of human–carnivore conflict on tiger and prey abundance and distribution in the Nam Et-Phou Louey National Protected Area on the Lao–Vietnam border. We conducted intensive camera-trap sampling of large carnivores and prey at varying levels of human population and monitored carnivore depredation of livestock across the protected area. The relative abundance of large ungulates was low throughout whereas that of small prey was significantly higher where human density was lower. The estimated tiger density for the sample area ranged from 0.2 to 0.7 per 100 km². Tiger abundance was significantly lower where human population and disturbance were greater. Three factors, commercial poaching associated with livestock grazing followed by prey depletion and competition between large carnivores, are likely responsible for tiger abundance and distribution. Maintaining tigers in the country's protected areas will be dependent on the spatial separation of large carnivores and humans by modifying livestock husbandry practices and enforcing zoning.     

The influence of lunar cycles on crop‐raiding elephants; evidence for risk avoidance

Long‐term solutions to crop raiding by elephants (Loxodonta africana) should be based on an understanding of their behaviour and ecology. The real and perceived risks from humans have been shown to affect elephant behaviour. This is evidenced by elephants predominantly raiding crops at night, avoiding the height of human activity. If such human avoidance behaviours are apparent, it might also be expected that elephants avoid risks associated with higher visibility and increased human activity as may occur during the full moon. However, elephant nocturnal crop‐raiding behaviour in relation to lunar cycles has largely been a neglected factor in studies of human–elephant interactions. In this study around Mikumi National Park, Tanzania, we apply circular statistics in this context for the first time to show a significant decrease in crop raiding during the full moon and apply this method retrospectively to data from another site in West Africa with similar results. Additionally, a greater proportion of farms raided was guarded during the full moon than any other moon phase. Our results indicate that variations in crop raiding with lunar phase could be a general feature of elephant behaviour and thus could be used to design and time mitigation efforts.     

Genetic diversity in the North American captive African elephant collection

One hundred and eight mitochondrial DNA (mtDNA) sequences were used in combination with multilocus genotypes generated from 19 nuclear microsatellite loci to assess the genetic diversity in the North American captive African elephant collection. The analysis of 4488 bp of mitochondrial nicotinamide adenine dinucleotide hydrogenenase subunit 4-cytochrome b (ND4-cyt b ) sequence revealed the existence of three distinct mtDNA lineages (Haplogroups I–III). The genetic distance between Haplogroups I/II and Haplogroup III was determined to be 0.046. The nucleotide diversity for the elephant mtDNA ND4-cyt b was <0.004. Analysis of multilocus genotypes indicated an average observed heterozygosity of 0.53 compared with the expected heterozygosity of 0.64. No subdivision in the data was detected including data partitioned by mtDNA haplogroup. Relatedness among the 108 individuals did not differ from that expected in random mating populations.     

Sexual antagonism leads to a mosaic of X-autosome conflict

Males and females have different optimal values for some traits, such as body size. When the same genes control these traits in both sexes, selection pushes in opposite directions in males and females. Alleles at autosomal loci spend equal amounts of time in males and females, suggesting that the sexually antagonistic selective forces may approximately balance between the opposing optima. Frank and Crespi noted that alleles on the X chromosome spend twice as much time in diploid females as in haploid males. That distinction between the sexes may tend to favor X-linked genes that push more strongly toward the female optimum than the male optimum. The female bias of X-linked genes opposes the intermediate optimum of autosomal genes, potentially creating a difference between the direction of selection on traits favored by X chromosomes and autosomes. Patten has recently argued that explicit genetic assumptions about dominance and the relative magnitude of allelic effects may lead X-linked genes to favor the male rather than the female optimum, contradicting Frank and Crespi. This article combines the insights of those prior analyses into a new, more general theory. We find some parameter combinations for X-linked loci that favor a female bias and other parameter combinations that favor a male bias. We conclude that the X likely contains a mosaic pattern of loci that differ with autosomes over sexually antagonistic traits. The overall tendency for a female or male bias on the X depends on prior assumptions about the distribution of key parameters across X-linked loci. Those parameters include the dominance coefficient and the way in which ploidy influences the magnitude of allelic effects.     

An empirical evaluation of the African elephant as a focal species for connectivity planning in East Africa

Aim Large, charismatic and wide‐ranging animals are often employed as focal species for prioritizing landscape linkages in threatened ecosystems (i.e. ‘connectivity conservation’), but there have been few efforts to assess empirically whether focal species co‐occur with other species of conservation interest within potential linkages. We evaluated whether the African elephant (Loxodonta africana), a world‐recognized flagship species, would serve as an appropriate focal species for other large mammals in a potential linkage between two major protected area complexes. Location A 15,400 km² area between the Ruaha and Selous ecosystems in central Tanzania, East Africa. Methods We used walking transects to assess habitat, human activity and co‐occurrence of elephants and 48 other large mammal species (> 1 kg) at 63 sites using animal sign and direct sightings. We repeated a subset of transects to estimate species detectability using occupancy modelling. We used logistic regression and AIC model selection to characterize patterns of elephant occurrence and assessed correlation of elephant presence with richness of large mammals and subgroups. We considered other possible focal species, compared habitat‐based linear regression models of large mammal richness and used circuit theory to examine potential connectivity spatially. Results Elephants were detected in many locations across the potential linkage. Elephant presence was highly positively correlated with the richness of large mammals, as well as ungulates, carnivores, large carnivores and species > 45 kg in body mass (‘megafauna’). Outside of protected areas, both mammal richness and elephant presence were negatively correlated with human population density and distance from water. Only one other potential focal species was more strongly correlated with species richness than elephants, but detectability was highest for elephants. Main conclusions Although African elephants have dispersal abilities that exceed most other terrestrial mammals, conserving elephant movement corridors may effectively preserve habitat and potential landscape linkages for other large mammal species among Tanzanian reserves.     

Predictors of elephant poaching in a wildlife crime hotspot: The Ruvuma landscape of southern Tanzania and northern Mozambique

Understanding the spatial distribution of elephant carcasses in relation to ecological characteristics and human activities is critical to developing targeted management strategies for reducing poaching. We employ a spatial modelling approach to quantify the relative contribution of multiple climatic, ecological, human and protected area management predictors of the number of elephant carcasses in a recognized poaching hotspot: the Ruvuma landscape of northern Mozambique and southern Tanzania. This includes the Niassa Reserve in the south and the Selous Game Reserve in the north. In Mozambique, the number of elephant carcasses is positively associated with State-managed protected areas such as Niassa Reserve, but particularly with environmental variables including low rainfall and high temperatures. In Tanzania, elephant carcasses are positively associated with community-managed sites. A strong focus on effective management of protected areas in the Ruvuma landscape is crucial to reducing the killing of elephants.     

Quantifying past and present connectivity illuminates a rapidly changing landscape for the African elephant

There is widespread concern about impacts of land‐use change on connectivity among animal and plant populations, but those impacts are difficult to quantify. Moreover, lack of knowledge regarding ecosystems before fragmentation may obscure appropriate conservation targets. We use occurrence and population genetic data to contrast connectivity for a long‐lived mega‐herbivore over historical and contemporary time frames. We test whether (i) historical gene flow is predicted by persistent landscape features rather than human settlement, (ii) contemporary connectivity is most affected by human settlement and (iii) recent gene flow estimates show the effects of both factors. We used 16 microsatellite loci to estimate historical and recent gene flow among African elephant (Loxodonta africana) populations in seven protected areas in Tanzania, East Africa. We used historical gene flow (F_ST and G'_ST) to test and optimize models of historical landscape resistance to movement. We inferred contemporary landscape resistance from elephant resource selection, assessed via walking surveys across ~15 400 km² of protected and unprotected lands. We used assignment‐based recent gene flow estimates to optimize and test the contemporary resistance model, and to test a combined historical and contemporary model. We detected striking changes in connectivity. Historical connectivity among elephant populations was strongly influenced by slope but not human settlement, whereas contemporary connectivity was influenced most by human settlement. Recent gene flow was strongly influenced by slope but was also correlated with contemporary resistance. Inferences across multiple timescales can better inform conservation efforts on large and complex landscapes, while mitigating the fundamental problem of shifting baselines in conservation.     

亚洲象生境长时序变化及其对人象冲突的影响——基于融合MaxEnt与HSI模型的生境适宜性评价方法

生境变化直接关系到物种种群维持与人类安全,揭示其长期变化规律及其对人类的影响,可为物种保护与生境恢复提供科学支撑。但因受物种活动点数据获取与位置精度的局限,鲜见濒危、危险物种的长时序生境变化研究。以人象冲突频发的西双版纳勐海—普洱澜沧地区亚洲象种群(勐海—澜沧象群)活动区为例,提出融合MaxEnt与HSI模型的亚洲象长时序生境适宜性评价方法,即基于荟萃分析筛选出的15个亚洲象生境评价因子,结合近期有限的物种活动点监测数据,利用MaxEnt得到生境评价因子的贡献率,再运用HSI模型计算生境适宜性指数;利用该方法制作出研究区1988—2020年逐年时序的亚洲象生境适宜性图,以分析亚洲象生境的时空变化,将其与亚洲象肇事数据结合,进而分析人象冲突与生境变化的关联。结果表明：(1)基于物种生境偏好不变的前提,融合MaxEnt模型与HSI模型的生境适宜性评价方法可应用于物种的长时序生境评价,且基于亚洲象活动点数据从动物对生境利用的生态学视角定量获取亚洲象对各生境评价因子的偏好程度,使生境评价结果具有良好的生态可解释性;(2)目前亚洲象适宜生境面积占研究区面积三分之一(4039.76 km^...     

Post-bottleneck genetic diversity of elephant populations in South Africa, revealed using microsatellite analysis

Widespread hunting had fragmented and severely reduced elephant populations in South Africa by 1900. Elephant numbers increased during the 1900s, although rates of recovery of individual populations varied. The Kruger National Park elephant population increased rapidly, to more than 6000 by 1967, with recruitment boosted by immigration from Mozambique. The Addo Elephant National Park population was reduced to 11 elephants in 1931 and remains relatively small (n = 325). Loss of genetic variation is expected to occur whenever a population goes through a bottleneck, especially when post-bottleneck recovery is slow. Variation at nine polymorphic microsatellite loci was analysed for Kruger and Addo elephants, as well as museum specimens of Addo elephants shot prior to the population bottleneck. Significantly reduced genetic variation and heterozygosity were observed in Addo in comparison to Kruger (mean alleles/locus and H(E): Addo 1.89, 0.18; Kruger 3.89, 0.44). Two alleles not present in the current Addo population were observed in the museum specimens. Addo elephants represent a genetic subset of the Kruger population, with high levels of genetic differentiation resulting from rapid genetic drift. The Kruger population is low in genetic diversity in comparison to East African elephants, confirming this population also suffered an appreciable bottleneck.