Megaherbivores modify forest structure and increase carbon stocks through multiple pathways

Megaherbivores have pervasive ecological effects. In African rainforests, elephants can increase aboveground carbon, though the mechanisms are unclear. Here we combine a large unpublished dataset of forest elephant feeding with published browsing preferences totaling > 120,000 records covering 700 plant species, including nutritional data for 102 species. Elephants increase carbon stocks by: 1) promoting high wood density tree species via preferential browsing on leaves from low wood density species, which are more digestible; 2) dispersing seeds of trees that are relatively large and have the highest average wood density among tree guilds based on dispersal mode. Loss of forest elephants could cause a 5-12% decline in carbon stocks due to regeneration failure of elephant-dispersed trees and an increase in abundance of low wood density trees. These results show the major importance of megaherbivores in maintaining diverse, high-carbon tropical forests. Successful elephant conservation will contribute to climate mitigation at a scale of global relevance.

Does Social Complexity Drive Vocal Complexity? Insights from the Two African Elephant Species

The social complexity hypothesis (SCH) for communication states that the range and frequency of social interactions drive the evolution of complex communication systems. Surprisingly, few studies have empirically tested the SHC for vocal communication systems. Filling this gap is important because a co-evolutionary runaway process between social and vocal complexity may have shaped the most intricate communication system, human language. We here propose the African elephant Loxodonta spec. as an excellent study system to investigate the relationships between social and vocal complexity. We review how the distinct differences in social complexity between the two species of African elephants, the forest elephant L. cyclotis and the savanna elephant L. africana, relate to repertoire size and structure, as well as complex communication skills in the two species, such as call combination or intentional formant modulation including the trunk. Our findings suggest that Loxodonta may contradict the SCH, as well as other factors put forth to explain patterns of vocal complexity across species. We propose that life history traits, a factor that has gained little attention as a driver of vocal complexity, and the extensive parental care associated with a uniquely low and slow reproductive rate, may have led to the emergence of pronounced vocal complexity in the forest elephant despite their less complex social system compared to the savanna elephant. Conclusions must be drawn cautiously, however. A better understanding of vocal complexity in the genus Loxodonta will depend on continuing advancements in remote data collection technologies to overcome the challenges of observing forest elephants in their dense rainforest habitat, as well as the availability of directly comparable data and methods, quantifying both structural and contextual variability in the production of rumbles and other vocalizations in both species of African elephants.

Population Genetic Structure and Historical Demography of the Population of Forest Elephants in Côte d’Ivoire

The population of forest elephant has continuously declined in Côte d’Ivoire and, the remaining population largely consists of small populations that are fragmented and isolated. No data actually exist on the level of genetic diversity and population genetic structure of current forest elephant populations in Côte d’Ivoire need to be highlighted. In this sense, determining genetic diversity and the underlying mechanisms of population differentiation is crucial for the initiation of effective conservation management. Forest elephant dung samples were collected in three forest reserves (FR) in Côte d’Ivoire. The total genomic DNA was extracted from these samples, A total of 101 sequences of the mitochondrial DNA control region measuring 600 base pair and 31 haplotypes were obtained. A haplotypic diversity ranging from 0.655 ± 0.050 at Bossématié and 0.859 ± 0.088 at Port Gauthier was obtained. More than half (16 of 31) of the haplotypes observed were singletons and only the Dassioko and Port Gauthier FRs shared the same haplotypes. The strong genetic connectivity between forest elephant populations of the Dassioko and Port Gauthier FRs is supported by the grouping of these populations into a single cluster by Bayesian analysis and principal component analysis. Although populations of Loxodonta cyclotis still exhibit relatively high genetic diversity, habitat fragmentation has already affected the genetic variability of current populations. Urgent measures including the reinforcement/establishment of genetic corridors and the strengthening of protection measures need to be undertaken to save the remaining populations.

African forest elephant movements depend on time scale and individual behavior

The critically endangered African forest elephant (Loxodonta cyclotis) plays a vital role in maintaining the structure and composition of Afrotropical forests, but basic information is lacking regarding the drivers of elephant movement and behavior at landscape scales. We use GPS location data from 96 individuals throughout Gabon to determine how five movement behaviors vary at different scales, how they are influenced by anthropogenic and environmental covariates, and to assess evidence for behavioral syndromes—elephants which share suites of similar movement traits. Elephants show some evidence of behavioral syndromes along an ‘idler’ to ‘explorer’ axis—individuals that move more have larger home ranges and engage in more ‘exploratory’ movements. However, within these groups, forest elephants express remarkable inter-individual variation in movement behaviours. This variation highlights that no two elephants are the same and creates challenges for practitioners aiming to design conservation initiatives.

Activity of Forest Elephant (Loxodonta cyclotis) In Two Clearings within Ogooué Leketi National Park, Congo Brazzaville

In order to increase our understanding of forest elephant (Loxodonta cyclotis) vocal communication, this study examined the spatial and temporal activity of elephants from two forest clearings (Bissoloko and Madjouama). To obtain data on the visit of elephant in the clearings daily, it requires considerable human and financial resources for conservation programs observations. However, we deployed autonomous acoustic recorders “SM2” to assess elephants’ activities both day and night time from 2013 to 2014. Elephant visitation in these clearings depends on certain factors as, seasons, years, and preferences of elephant to use one or more site. As a results this study found that (i) elephants visited Bissoloko clearing more than Madjouama, although these two clearings were within 5 km distant one another; (ii) Eighty six per cent of elephant calls occurred at night, and large changes in call density at night often were not reflected in similar changes during the day; (iii) there were significant differences in the calls made at night; (iv) elephants were found to be visiting clearings more often in the wet season than in the dry season; (v) visitation was significantly higher in 2013 than in 2014. Elephants used randomly one or other clearings. This empirical study suggests that African forest elephant has two vocal communication practices. Spatially separated females engage in rumble exchanges that help them to coordinate their movements and to bring them together. Both male and female elephants produce "mate attraction" rumbles to inform the opposite sex of their reproductive status. These results show the value of acoustic monitoring as a tool for better understanding of forest elephant behaviour. We suggest that passive acoustic monitoring should be incorporated into forest elephant monitoring programs to complement direct observations at forest clearings.

Molecular identification and geographic origin of a post-Medieval elephant finding from southwestern Portugal using high-throughput sequencing

Molecular species identification plays a crucial role in archaeology and palaeontology, especially when diagnostic morphological characters are unavailable. Molecular markers have been used in forensic science to trace the geographic origin of wildlife products, such as ivory. So far, only a few studies have applied genetic methods to both identify the species and circumscribe the provenance of historic wildlife trade material. Here, by combining ancient DNA methods and genome skimming on a historical elephantid tooth found in southwestern Portugal, we aimed to identify its species, infer its placement in the elephantid phylogenetic tree, and triangulate its geographic origin. According to our results the specimen dates back to the eighteenth century CE and belongs to a female African forest elephant (non-hybrid Loxodonta cyclotis individual) geographically originated from west—west-central Africa, from areas where one of the four major mitochondrial clades of L. cyclotis is distributed. Historical evidence supports our inference, pointing out that the tooth should be considered as post-Medieval raw ivory trade material between West Africa and Portugal. Our study provides a comprehensive approach to study historical products and artefacts using archaeogenetics and contributes towards enlightening cultural and biological historical aspects of ivory trade in western Europe.

Responses to a poached conspecific in wild forest elephants (Loxodonta africana cyclotis)

The increased attention towards deceased conspecifics in various social animal species is one of the most intriguing conundrums in animal behaviour. The factors that might explain the observed behavioural variation amongst individuals remain nebulous. Here we analyse forest elephants’ (Loxodonta africana cyclotis) responses to a poached adult male conspecific, using remote camera trapping during a period of eight months. After completely avoiding the carcass site for over a week, females and males substantially differed in behavioural responses. Males consistently stayed longer around the remains, showed signs of increased arousal, interacted with the dead body, and twisted trunks with each other. Females, in contrast, were more passively explorative and preferred to visit the site without their dependent offspring. Findings show a previously unknown sexual-dimorphism in forest elephant behaviour towards a poached conspecific and raise the possibility that individuals might be able to infer further context-specific information about the event.