Identification et caractérisation de la dynamique de la grande faune dans le baï de Momba (nord-est Gabon)

Les baïs sont des clairières marécageuses localisées généralement au coeur des forêts du Bassin du Congo. Ce sont des écosystèmes particulièrement riches en espèces animales et végétales. Si les connaissances portant sur l’origine de ces milieux sont bien documentées, les espèces de la faune sauvage (éléphants, buffles, sitatungas, etc.) colonisant ces écosystèmes demeurent encore mal connues. Par ailleurs, les informations qui existent sur ces espèces fauniques restent fragmentaires. C’est pour ces raisons qu’une étude basée sur les méthodes d’observation de la faune (scan sampling et animal focal) a été conduite dans le baï de Momba durant 33 jours. Ce travail visait l’identification de la macrofaune présente dans ce type de milieux et l’analyse de la dynamique de cette faune. Au total, 969 animaux ont été observés. Ces animaux ont été représentés majoritairement par les sitatungas (Tragelaphus spekei), les éléphants (Loxodonta africana cyclotis), les buffles (Syncerus caffer nanus) et les colobes (Colobus guereza). En termes de fréquence d’observation, les sitatungas (27%) ont été le groupe le plus abondant, suivis par les éléphants (8%) et les buffles (7%). Les autres animaux ont été faiblement observés avec une fréquence de moins de 2%. La fréquentation du baï de Momba par ces espèces témoigne du rôle crucial que pourrait jouer les zones humides dans la gestion durable de la biodiversité dans le Bassin du Congo. Aussi, il apparaît nécessaire que des mesures de protection et de suivi de la dynamique de ces peuplements soient rapidement entreprises afin de protéger la biodiversité faunique de cemilieu.Mots clés : Loxodonta africana cyclotis, Syncerus caffer nanus, Tragelaphus spekei,Colobus guereza, baï de Momba, Gabon

The emergence of a commercial trade in pangolins from Gabon

Recent seizures of illegally-held wildlife indicate a mounting global trade in pangolins involving all eight species. Seizures of illegally-traded African pangolins are increasing as wild populations of Asian species decline. We investigated trade in pangolins and law enforcement efforts in Gabon; a country likely to have intact wild populations of three of the four species of African pangolin. We compared village sales and trade chains between 2002-3 and 2014. Hunters reported pangolins to be the most frequently requested species in 2014 and the value of pangolins had increased at every point along their trade chain. In Libreville, giant pangolin prices increased 211% and arboreal pangolin prices 73% whilst inflation rose only 4.6% over the same period. We documented a low rate of interception of illegally-traded pangolins despite increased law enforcement. Surveys of potential export routes detected exports across forest borders, in conjunction with ivory, but not through public transport routes. We conclude that whilst there is clear potential and ikelihood that a wild pangolin export trade is emerging from Gabon, traditional bushmeat trade chains may not be the primary supply route. We recommend adjusting conservation policies and actions to impede further development of illegal trade within and from Gabon

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

Climatic and Resource Determinants of Forest Elephant Movements

As a keystone megafaunal species, African forest elephants (Loxodonta cyclotis) influence the structure and composition of tropical forests. Determining the links between food resources, environmental conditions and elephant movement behavior is crucial to understanding their habitat requirements and their effects on the ecosystem, particularly in the face of poaching and global change. We investigate whether fruit abundance or climate most strongly influence forest elephant movement behavior at the landscape scale in Gabon. Trained teams of “elephant trackers” performed daily fruit availability and dietary composition surveys over a year within two relatively pristine and intact protected areas. With data from 100 in-depth field follows of 28 satellite-collared elephants and remotely sensed environmental layers, we use linear mixed-effects models to assess the effects of sites, seasons, focal elephant identification, elephant diet, and fruit availability on elephant movement behavior at monthly and 3-day time scales. At the month-level, rainfall, and to a lesser extent fruit availability, most strongly predicted the proportion of time elephants spent in long, directionally persistent movements. Thus, even elephants in moist tropical rainforests show seasonal behavioral phenotypes linked to rainfall. At the follow-level (2–4 day intervals), relative support for both rainfall and fruit availability decreased markedly, suggesting that at finer spatial scales forest elephants make foraging decisions largely based on other factors not directly assessed here. Focal elephant identity explained the majority of the variance in the data, and there was strong support for interindividual variation in behavioral responses to rainfall. Taken together, this highlights the importance of approaches which follow individuals through space and time. The links between climate, resource availability and movement behavior provide important insights into the behavioral ecology of forest elephants that can contribute to understanding their role as seed dispersers, improving management of populations, and informing development of solutions to human-elephant conflict

Data from: Vertebrate community composition and diversity declines along a defaunation gradient radiating from rural villages in Gabon

Anthropocene defaunation is the global phenomenon of human-induced animal biodiversity loss. Understanding the patterns and process of defaunation is critical to predict outcomes for wildlife populations and cascading consequences for ecosystem function and human welfare. We investigated a defaunation gradient in northeastern Gabon by establishing 24 transects at varying distances (2–30 km) to rural villages and surveying the abundance and composition of vertebrate communities. Distance from village was positively correlated with observations of hunting (shotgun shells, campfires, hunters), making it a good proxy for hunting pressure. Species diversity declined significantly with proximity to village, with mammal richness increasing by roughly 1.5 species every 10 km travelled away from a village. Compared to forest far from villages, the wildlife community near villages consisted of higher abundances of large birds and rodents and lower abundances of large mammals like monkeys and ungulates. Distance to nearest village emerged as a key driver of the relative abundance of five of the six taxonomic guilds, indicating that the top–down force of hunting strongly influences large vertebrate community composition and structure. Several measures of vegetation structure also explained animal abundance, but these varied across taxonomic guilds. Forest elephants were the exception: no measured variable or combination of variables explained variation in elephant abundances. Synthesis and applications. Hunting is concentrated within 10 km around villages, creating a hunting halo characterized by heavily altered animal communities composed of relatively small-bodied species. Although the strongest anthropogenic effects are relatively distance-limited, the linear increase in species richness shown here even at distances 30 km from villages suggests that hunting may have altered vertebrate abundances across the entire landscape. Central African forests store >25% of the carbon in tropical forests and are home to 3000 endemic species, but roughly 53% of the region lies within the village hunting halo. Resource management strategies should take into account this hunting-induced spatial variation in animal communities. Near villages, resource management should focus on sustainable community-led hunting programs that provide long-term supplies of wild meat to rural people. Resource management far from villages should focus on law enforcement and promoting industry practices that maintain remote tracts of land to preserve ecosystem services like carbon storage and biodiversity

IvindoData_DryadVersion

Large vertebrate community data and environmental characteristics for 24 2-km transects with varying hunting intensities in the Ivindo landscape in northeast Gabon