The consequences of poaching and anthropogenic change for forest elephants

Poaching has devastated forest elephant populations (Loxodonta cyclotis), and their habitat is dramatically changing. The long-term effects of poaching and other anthropogenic threats have been well studied in savannah elephants (Loxodonta africana), but the impacts of these changes for Central Africa's forest elephants have not been discussed. We examine potential repercussions of these threats and the related consequences for forest elephants in Central Africa by summarizing the lessons learned from savannah elephants and small forest elephant populations in West Africa. Forest elephant social organisation is little known than for savannah elephants, but the close evolutionary history with savannah elephants suggests that they will respond to anthropogenic threats in broadly similar ways. The loss of older, experienced individuals could disrupt ecological, social and population parameters. Severe reduction of elephant abundance within Central Africa's forests can alter plant communities and ecosystem functions. Poaching, habitat alterations and human population increase are probably compressing forest elephants into protected areas and increasing human-elephant conflict, negatively affecting their conservation. We encourage conservationists to look beyond forest elephant population decline and address these causes of change when developing conversation strategies. We propose research priorities, including assessing the effectiveness of the existing protected area network for landscape connectivity in the light of current industrial and infrastructure development. Longitudinal assessments of landscape changes on forest elephant sociality and behaviour are also needed. Finally, lessons learned from West African population loss and fragmentation should be used to inform strategies for land-use planning and managing the human-elephant interface

Quantifying forest elephant social structure in Central African bai environments

Relatively little is known of social dynamics in forest elephants (Loxodonta africana cyclotis), although the fission-fusion model of sociality known in savannah elephants (Loxodonta africana africana) is used as a template. Until fission-fusion sociality or an alternative model is demonstrated, our understanding of how elephants use their environment remains incomplete. To date, there have been no published studies of associations between individuals in forest elephants. Direct observations of forest elephants made at forest clearings (bais) are here used as an approach to studying these questions. Bais represent a special environment, providing mineral and food resources, as well as potential social opportunities. We show that forest elephants at Mbeli Bai in Nouabalé-Ndoki National Park have association patterns that are consistent over time, and that certain conspecifics are preferred as associates in the bai environment. Coupled with significant differences in the group size and composition across age-sex classes, and a high proportion of sightings of lone individuals, we argue that the fission-fusion model of elephant sociality appears to hold for the bai environment. The extent of this system and the importance of bais as social resources remain to be explored

First observation of tool use in wild gorillas

Descriptions of novel tool use by great apes in response to different circumstances aids us in understanding the factors favoring the evolution of tool use in humans. This paper documents what we believe to be the first two observations of tool use in wild western gorillas(Gorilla gorilla). We first observed an adult female gorilla using a branch as a walking stick to test water deepness and to aid in her attempt to cross a pool of water at Mbeli Bai, a swampy forest clearing in northern Congo. In the second case we saw another adult female using a detached trunk from a small shrub as a stabilizer during food processing. She then used the trunk as a self-made bridge to cross a deep patch of swamp. In contrast to information from other great apes, which mostly show tool use in the context of food extraction, our observations show that in gorillas other factors such as habitat type can stimulate the use of tools

The reproductive advantages of a long life: longevity and senescence in wild female African elephants

Long-lived species such as elephants, whales and primates exhibit extended post-fertile survival compared to species with shorter lifespans but data on age-related fecundity and survival are limited to few species or populations. We assess relationships between longevity, reproductive onset, reproductive rate and age for 834 longitudinally monitored wild female African elephants in Amboseli, Kenya. The mean known age at first reproduction was 13.8years; only 5% commenced reproduction by 10years. Early reproducers (<12.5years) had higher age-specific fertility rates than did females who commenced reproduction late (15+ years) with no differences in survival between these groups. Age-specific reproductive rates of females dying before 40years were reduced by comparison to same-aged survivors, illustrating a mortality filter and reproductive advantages of a long life. Overall, 95% of fertility was completed before 50, and 95% of mortality experienced by age 65, with a mean life expectancy of 41years for females who survived to the minimum age at first birth (9years). Elephant females have a relatively long period (c. 16years) of viability after 95% completed fertility, although reproduction does not entirely cease until they are over 65. We found no evidence of increased investment among females aged over 40 in terms of delay to next birth or calf mortality. The presence of a mother reproducing simultaneously with her daughter was associated with higher rates of daughter reproduction suggesting advantages from maternal (and grandmaternal) co-residence during reproduction

Individual-based modelling of elephant population dynamics using remote sensing to estimate food availability

Strategies for the conservation and management of many wild species requires an improved understanding of how population dynamics respond to changes in environmental conditions, including key drivers such as food availability. The development of mechanistic predictive models, in which the underlying processes of a system are modelled, enables a robust understanding of these demographic responses to dynamic environmental conditions. We present an individual-based energy budget model for a mega-herbivore, the African elephant (Loxodonta africana), which relates remotely measured changes in food availability to vital demographic rates of birth and mortality. Elephants require large spaces over which to roam in search of seasonal food, and thus are vulnerable to environmental changes which limit space use or alter food availability. The model is constructed using principles of physiological ecology; uncertain parameter values are calibrated using approximate Bayesian computation. The resulting model fits observed population dynamics data well. The model has critical value in being able to project elephant population size under future environmental conditions and is applicable to other mammalian herbivores with appropriate parameterisation

Human‐driven habitat conversion is a more immediate threat to Amboseli elephants than climate change

Global ecosystem change presents a major challenge to biodiversity conservation, which must identify and prioritize the most critical threats to species persistence given limited available funding. Mechanistic models enable robust predictions under future conditions and can consider multiple stressors in combination. Here we use an individual‐based model (IBM) to predict elephant population size in Amboseli, southern Kenya, under environmental scenarios incorporating climate change and anthropogenic habitat loss. The IBM uses projected food availability as a key driver of elephant population dynamics and relates variation in food availability to changes in vital demographic rates through an energy budget. Habitat loss, rather than climate change, represents the most significant threat to the persistence of the Amboseli elephant population in the 21st century and highlights the importance of collaborations and agreements that preserve space for Amboseli elephants to ensure the population remains resilient to environmental stochasticity

Animal cultures matter for conservation

Understanding the rich social lives of animals benefits international conservation efforts.PostprintPeer reviewe

Forest elephants: fission-fusion and social arenas

Fission-fusion systems provide models for studying grouping decisions and social complexity in a range of taxa, as individuals act to manage risks and enhance reproductive success. African savannah elephants, Loxodonta africana africana, live in a fluid society where individual relationships persist over decades and affect reproductive success. Social structures have yet to be fully characterized for forest elephants, Loxodonta africana cyclotis. Aggregations at natural forest clearings, which are frequent in this subspecies, may offer social benefits in addition to nutritional resources. We examined the social functions of aggregations in Odzala-Kokoua National Park, Republic of Congo. We tested whether clearings function as ‘social arenas' by examining how social opportunities affected the timing and duration of visits, and how short-term grouping decisions were affected by age, sex, group size and number of elephants present. Aggregations reflected a fission-fusion society similar to that observed in savannah elephants. Grouping patterns were largely unaffected by the number of elephants present, from which we infer that elephants were not acting to minimize competition. Social opportunities affected visit patterns such that visits were longer when others were present. Social opportunities were maximized by joining large groups, often including older elephants, or, for males, parties with females. Large and dynamically changing social groups in clearings offer potential for information exchange and the maintenance of social relationships. Demonstrating that fission-fusion operates in forest elephant society allows future research to focus on cost-benefit modelling, to understand the fitness consequences of these groupings

Elephant resource-use traditions

African elephants (Loxodonta africana) use unusual and restricted habitats such as swampy clearings, montane outcrops and dry rivers for a variety of social and ecological reasons. Within these habitats elephants focus on very specific areas for resource exploitation, resulting in deep caves, large forest clearings and sand pits as well as long-established and highly demarcated routes for moving between resources. We review evidence for specific habitat exploitation in elephants and suggest that this represents socially learned cultural behaviour. Although elephants show high fidelity to precise locations over the very long term, these location preferences are explained neither by resource quality nor by accessibility. Acquiring techniques for exploiting specific resource sites requires observing conspecifics and practice, and is evidence for social learning. Elephants possess sophisticated cognitive capacities used to track relationships and resources over their long lifespans and they have an extended period of juvenile dependency as a result of the need to acquire this considerable social and ecological knowledge. Thus, elephant fidelity to particular sites results in traditional behaviour over generations, with the potential to weaken relationships between resource quality and site preferences. Illustrating the evidence for such powerful traditions in a species such as elephants contributes to understanding animal cognition in natural contexts