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Poaching empties critical Central African wilderness of forest elephants
Abstract
Elephant populations are in peril everywhere, but forest elephants in Central Africa have sustained alarming losses in the last decade [1]. Large, remote protected areas are thought to best safeguard forest elephants by supporting large populations buffered from habitat fragmentation, edge effects and human pressures. One such area, the Minkébé National Park (MNP), Gabon, was created chiefly for its reputation of harboring a large elephant population. MNP held the highest densities of elephants in Central Africa at the turn of the century, and was considered a critical sanctuary for forest elephants because of its relatively large size and isolation. We assessed population change in the park and its surroundings between 2004 and 2014. Using two independent modeling approaches, we estimated a 78–81% decline in elephant numbers over ten years — a loss of more than 25,000 elephants. While poaching occurs from within Gabon, cross-border poaching largely drove the precipitous drop in elephant numbers. With nearly 50% of forest elephants in Central Africa thought to reside in Gabon [1], their loss from the park is a considerable setback for the preservation of the species.
... Minimum convex polygon (MCP) home ranges (Stickel, 1954) of these elephants were between 203 and 598km 2 , larger than a rabbit's, but considerably smaller than many estimates of savannah elephant ranges (e.g., Lindeque & Lindeque, 1991;Thouless, 1996;Verlinden & Gavor, 1998). Subsequent studies were developed mostly in response to the deepening conservation crisis facing forest elephants in the Congo Basin (Barnes, 1999;Barnes et al., 1995;Blake et al., 2007;Blake & Hedges, 2004;Maisels et al., 2013;Poulsen et al., 2017), with movement data collected from forested sites in Congo, Cameroon, Central African Republic, and Gabon and including forest/savannah mosaics in Gabon (Beirne et al., 2019(Beirne et al., , 2020Blake, 2002;Blake et al., 2001Blake et al., , 2008Mills et al., 2018;Molina-Vacas et al., 2020;Poulsen et al., 2021;Rosin et al., 2020). In total, at least 130 GPS collars have been successfully deployed on forest elephants since 1994. ...
... The most recent assessment of Gabon's elephants suggested that most of them live outside the protected areas and still occur at high density in both protected areas and logging concessions (Laguardia et al., 2021). It seems almost inconceivable that the vast forests of the Congo Basin and their elephants could be similarly impacted, yet elephants are all but extinct in the Democratic Republic of Congo (Blake et al., 2007;Maisels et al., 2013) and declined dramatically in northeast Gabon (Poulsen et al., 2017). ...
... We remain in the infancy of understanding patterns of forest elephant movements and the spatiotemporal dynamics of their habitats. Low sample sizes, the scale and complexity of movement strategies, and the variability among individuals merely highlight the urgency of long stated management objectives (Blake et al., 2007;Maisels et al., 2013;Poulsen et al., 2017;Turkalo et al., 2016), namely, effective protection of multiple large tracts of interconnected high-quality forest throughout the range of forest elephants. But once again, how large is large? ...
To survive, all organisms must maximize energy input and reproductive output and minimize risk. This applies to how they travel through their environment. Due to numerous mechanical and physical laws that scale allometrically, forest elephants (Loxodonta cyclotis), as the largest vertebrate inhabitants of Africa’s dense tropical forests, solve this optimization in rather different ways than the smallest, for example, shrews. In this chapter, we discuss how body size influences animal ranging and why elephants ought to have very large ranges. We then use GPS telemetry data we collected ourselves and additional data from published studies to characterize home range size and other movement metrics of forest elephants in Central Africa. We demonstrate how the availability of water, food, nutrients, social organization, sex, and personality combines to drive the movements of forest elephants. We conclude that these factors are largely trumped by a human-induced landscape of fear throughout the range of forest elephants. We explain how the combination of large body size and the extent of forest elephant movements lead to their profound ecosystem engineering impacts, which help maintain forest biodiversity and increase carbon sequestration. We then show how human activities, primarily poaching and infrastructure development, restrict elephant movements, with negative consequences for forest function that have globally relevant ramifications. We finally argue that if forest elephant movements in their present form are to be maintained, the planet’s rich nations must match and surpass the impressive legislation for protected areas made by forest elephant range states in their commitment to demand and create the economic conditions needed for the sustainable management of tropical forest resources, including elephants.KeywordsAnimal movementTropical forestCongo BasinConservationEcosystem engineerHome range
... Wildlife in Central Africa is under threat due to the loss of suitable habitat, unsustainable hunting, and commercial poaching (Blake et al. 2007;Junker et al. 2012;Abernethy et al. 2013). Particularly forest elephants (Loxodonta cyclotis) are declining dramatically throughout their range due to poaching activities triggered by international ivory demand (Blake et al. 2007;Maisels et al. 2013;Poulsen et al. 2017). Poaching and population declines of forest elephants can have far reaching consequences for ecological processes, people´s livelihoods, and on carbon storage capacities (Breuer et al. 2016;Poulsen et al. 2017;Berzaghi et al. 2019). ...
... Particularly forest elephants (Loxodonta cyclotis) are declining dramatically throughout their range due to poaching activities triggered by international ivory demand (Blake et al. 2007;Maisels et al. 2013;Poulsen et al. 2017). Poaching and population declines of forest elephants can have far reaching consequences for ecological processes, people´s livelihoods, and on carbon storage capacities (Breuer et al. 2016;Poulsen et al. 2017;Berzaghi et al. 2019). ...
... Long-term research sites such as the Mbeli Bai Study act as an early warning system against poaching and are also a successful deterrent against illegal human activities (Campbell et al. 2011;Tagg et al. 2015). As poaching at other sites has and continues to reduce elephant populations (Maisels et al. 2013;N´Goran et al. 2016;Poulsen et al. 2017), NNNP and the larger Sangha Trinational area with its large tracts of intact forest is one of the last strongholds and refuge areas for these mega-herbivores and other wildlife (Stokes et al;2010;Breuer et al. in press). Unfortunately, these last remaining pristine forests are increasingly threatened by human encroachment and extractive industries (Kleinschroth et al. 2019b;Morgan et al. 2019). ...
Understanding the ecological factors influencing African forest elephant (Loxodonta cyclotis) abundance and distribution is crucial for their conservation management in Central Africa. Dung surveys have been conducted at the landscape scale and confirmed the overwhelming impact of anthropogenic activities on forest elephants. We present results from a small-scale survey in a pristine protected area without anthropogenic activities to elucidate the ecological factors influencing forest elephant density. We conducted a line transect dung survey in a small study area (110 km²) around Mbeli Bai, a natural forest clearing in the Nouabalé-Ndoki National Park, Republic of Congo, and compare results with a landscape survey conducted during the same period. We used habitat specific dung decay data collected on site to estimate elephant density using distance sampling. We fitted Generalized Additive Models to elephant dung encounter rate using explanatory variables collected during the transect survey and from geospatial data. The small-scale survey revealed a precise estimate of forest elephant density that was twice as high as the result from a landscape survey with higher density in mixed species forest for the small-scale survey. We could not find an impact of the proximity of forest clearings and proximity to rivers at the small scale. Fine-scale habitat features, e.g. degree of canopy and understorey closure, had little explanatory power for elephant dung encounter rate. Small-scale dung surveys are a useful method to reveal spatio-temporal variation in forest elephant density and distribution which can inform conservation practitioners in a timely manner. Combining monitoring methods at various spatial scales improves our knowledge and conservation efforts of forest elephants. Nouabalé-Ndoki National Park is a stronghold for forest elephants and of global importance for their conservation.
... Surveys of animal sign typically count dung or nests (e.g. elephants, deer, great apes; Maisels et al., 2013;Plumptre, 2000a;Poulsen et al., 2017;Stokes et al., 2010;Todd et al., 2008). ...
... Large variation across sites has prevented adoption of a single decay rate, necessitating that practitioners derive costly and time-consuming, site-specific estimates of dung decay rate (Laing et al., 2003) or employ decay rates from other sites at the risk of introducing substantial error into abundance conversions. For example, Poulsen et al. (2017) found that varying defecation rate between 18.1 and 19 dung/day and decay time between 45 and 90 days yielded a difference of 9000 elephants -11% of the global populationin a single area (Maisels et al., 2013). ...
... We obtained transect data from surveys conducted in Minkébé National Park, Gabon in 2004 and 2014 (Blake, 2005;Poulsen et al., 2017). Blake (2005) reported results using a dung decay rate of 90 days, whereas Poulsen et al. (2017) reported results using three commonly used dung decay rates and a site-specific dung-rainfall model, underscoring the need for better dung degradation models. ...
Accurate and ecologically relevant wildlife population estimates are critical for species management. One of the most common survey methods for forest mammals – line transects for animal sign with distance sampling – has assumptions regarding conversion factors that, if violated, can induce substantial bias in abundance estimates. Specifically, for sign (e.g. nests, dung) surveys, a single number representing total time for decay is used as a multiplier to convert estimated sign density into animal density. This multiplier is likely inaccurate if not derived from a study reflecting the spatiotemporal variation in decay times. Using dung decay observations from three protected areas in Gabon, and a previous study in Nouabalé‐Ndoki National Park (Congo), we developed Weibull survival models to adaptively predict forest elephant (Loxodonta cyclotis) dung decay based on environmental variables from field collected and remotely sensed data. Seasonal decay models based on remotely sensed covariates explained 86% of the variation for the wet season and 79% for the dry season. These models included canopy cover, cloud cover, humidity, vegetation complexity and slope as factors influencing dung decay. With these models, we assessed sensitivity of elephant density estimates to spatiotemporal environmental heterogeneity, showing that our methods work best for large‐scale studies >50 km2. We simulated decay studies with and without these variables in four Gabonese national parks and reanalyzed two previous surveys of elephants in Minkébé National Park, Gabon. Disregarding spatial and temporal variation in decay rate biased population estimates up to 1.6 and 6.9 times. Our reassessment of surveys in Minkébé National Park showed an expected loss of 78% of forest elephants over ten years, but the elephant abundance was 222% higher than previously estimated. Our models incorporate field or remotely sensed variables to provide an ecological context essential for accurate population estimates while reducing need for expensive decay field studies. Population abundance for elusive species are estimated from sign counts and multipliers of sign production and decay rates. To combat the improper use of single decay rates often obtained from an unrepresentative site, we observed and modeled forest elephant dung decay rates and created adaptive models which incorporate spatiotemporal environmental variables. We showed that disregarding spatial and temporal variation in decay rate can bias population estimates by a factor of up to 1.6 and 6.9 times.
... forest clearings around a water resource) [2][3][4], although observations have been possible when the elephants occupy coastal or savanna habitats [5][6][7][8]. Studies of African forest elephants are critical given their conservation status and recently documented population declines [9,10], as well as their relevance for understanding the evolution of proboscideans [11,12]. ...
... Forest elephant populations have been dramatically decreasing over the past few decades for a number of reasons including habitat loss and poaching [9,26]. One recent study highlighted major population loss (78-81%) over a decade within a protected area in northeastern Gabon [10]. The authors argued that the primary reason for this decline is attributed to poaching. ...
... This discrepancy may be explained by either differences in methodology and/or a recent decline in forest elephant population size in the Gamba Complex. Given the catastrophic population declines seen elsewhere in Gabon [10], this latter potential scenario is worrying. However, there is little evidence that elephant hunting and habitat loss in the Gamba Complex is at a rate that would cause such a rapid demographic decline. ...
Population monitoring is critical to effective conservation, but forest living taxa can be difficult to directly observe. This has been true of African forest elephants (Loxodonta cyclotis), for which we have limited information regarding population size and social behavior despite their threatened conservation status. In this study, we estimated demographic parameters using genetic capture-recapture of forest elephants in the southern Industrial Corridor of the Gamba Complex of Protected Areas in southwestern Gabon, which is considered a global stronghold for forest elephants. Additionally, we examined social networks, predicting that we would find matrilineal structure seen in both savanna and forest elephants. Given 95% confidence intervals, we estimate population size in the sampled area to be between 754 and 1,502 individuals and our best density estimate ranges from 0.47 to 0.80 elephants per km². When extrapolated across the entire Industrial Corridor, this estimate suggests an elephant population size of 3,033 to 6,043 based on abundance or 1,684 to 2,832 based on density, approximately 40–80% smaller than previously suggested. Our social network analysis revealed approximately half of network components included females with different mitochondrial haplotypes suggesting a wider range of variation in forest elephant sociality than previously thought. This study emphasizes the threatened status of forest elephants and demonstrates the need to further refine baseline estimates of population size and knowledge on social behavior in this taxon, both of which will aid in determining how population dynamics in this keystone species may be changing through time in relation to increasing conservation threats.
... Le Gabon compte 22 parcs nationaux dont 13 parcs terrestres créés en 2002 et couvrants 11 % des 267 667 km² de superficie du territoire national 1 . Dès 2004, la situation du plus grand de ces parcs terrestres, le parc national de Minkébé au Nord-est du pays (7 567 km²), comptant la plus importante population d'éléphants des forêts au monde (9 000 individus estimés en 2013) (Poulsen et al., 2017 ;Vande Weghe, 2013), refléta de manière exacerbée les difficultés que connait l'Etat à exercer pleinement son autorité dans les lieux de patrimonialisation environnementale gabonais (Obame Ondo, 2011). Avec un territoire bien plus grand que celui du département des Pyrénées-Atlantiques en France 7 645 km² 2 , les limites du parc national de Minkébé sont adossées à des segments de dyades que partage le Gabon avec le Cameroun au Nord et la République du Congo à l'Est. ...
... La politique environnementale comme acte d'appropriation esthétiques du territoire (Kialo et al., 2011). Poulsen et al. (2017) (Héritier et al., 2008). Cette action fait référence au contrôle direct exercé sur un territoire par un Etat (Rosière, 2013). ...
... r des acteurs des marchés transétatiques illégaux. Cette situation s'observe d'ailleurs aisément dans d'autres parties du territoire gabonais à forte valeur écologique mais jusque-là non-exploitées et non intégrées au reste du corps territorial comme le confirme l'actuel directeur technique de l'Agence nationale des parcs nationaux, Ella Ekogha 6 .Poulsen et al. (2017) (ANPN, WCS, WWF, 2013) relève que l'impact négatif de la dyade Gabon-Cameroun sur la population d'éléphants avec des braconniers provenant essentiellement du Cameroun où la route nationale passe à 6,1 km du parc national de Minkébé au Gabon. Cette proximité entre le parc au Gabon et cette infrastructure du réseau de transport Camerounai ...
This article analyzes the stakes surrounding the establishment of a protected area in the Minkébé forest in northeast Gabon. It deals with the various strategies of appropriation implemented by the Gabonese State to control this part of the territory at this part of border that separating Gabon from Cameroon to the North and Congo to the East. Long kept out of the socio-economic dynamic, Minkébé is now the target of informal activities and illegal trans-state organizations. The purpose of this publication is to show the deployment of public authority in this part of the country through a multifunctional appartus
... However, elephants can impose considerable social and financial costs on farmers by damaging crops, food stores, and water sources, thus impairing local farmers' well-being (Mackenzie and Ahabyona 2012, Barua et al. 2013). In addition to poaching (Poulsen et al. 2017), land-use change, and habitat loss (Chartier et al. 2011), retaliatory killing of elephants poses a serious threat to the species' survival. The increasing intensity of elephant-related conflicts highlights the pressing need to develop a better understanding of farmers' decision-making and its underpinnings (Evans andAdams 2018, Shaffer et al. 2019). ...
... Technical interventions to reduce agricultural damage by elephants at a local level tend to focus on physical and biological barriers such as fencing, guarding, and the use of repellents (Nyhus 2016, Pozo et al. 2019. Economic instruments, either through compensation mechanisms for crop losses (Ravenelle and Nyhus 2017) or financial incentives that reward a specific conservation outcome, have also been suggested as effective solutions to conservation conflicts (White andHanley 2016, Wilson et al. 2017). Incentive-based instruments also include agglomeration payments, which encourage spatial coordination of land set aside for conservation by offering additional payments to farmers enroling adjacent parcels in agrienvironment schemes (Parkhurst and Shogren 2007). ...
Conflicts between biodiversity conservation and other human activities are multifaceted. Understanding farmer preferences for various conflict mitigation strategies is therefore critical. We developed a novel interactive game around farmer land management decisions across 18 villages in Gabon to examine responses to three elephant conflict mitigation options: use of elephant deterrent methods, flat-rate subsidy, and agglomeration payments rewarding coordinated action for setting land aside for elephants. We found that all three policies significantly reduced participants' inclinations to engage in lethal control. Use of deterrents and agglomeration payments were also more likely to reduce decisions to kill elephants in situations where levels of social equity were higher. Only the two monetary incentives increased farmers' predisposition to provide habitats for elephants, suggesting that incentive-based instruments were conducive to pro-conservation behavior; different subsidy levels did not affect responses. Likewise, neither participants' socioeconomic characteristics nor their real-life experiences of crop damage by elephants affected game decisions. Killing behavior in the games was 64% lower in villages influenced by protected areas than in villages surrounded by logging concessions, highlighting the need to address conservation conflicts beyond protected areas. Our study shows the importance of addressing underlying social conflicts, specifically equity attitudes, prior to, or alongside addressing material losses.
... African forest elephants (L. cyclotis) are critically endangered and most populations have crashed under hunting pressure and habitat loss [9][10][11], but savannah elephant (L. africanus) and hybridized African elephant populations are rebounding in some forest parks [12,13]. ...
Crop loss to wildlife, particularly elephants, threatens livelihoods and support for conservation around many protected areas in Africa and Asia. Low-cost elephant barriers have been successfully deployed in savannas but seldom tested around isolated forest parks where the stakes are high for local farmers and isolated elephant populations. We measured the effectiveness of a series of ≥3 m deep trenches dug by farmers neighboring Kibale National Park, Uganda. We monitored trench quality and crop loss to elephants weekly for a year across 47 transects in four park-adjacent communities, and conducted controlled, before-and-after comparisons of verified damage. Elephants damaged or destroyed >4 ha of crops during 48 independent foraging events, the majority <220m from the forest boundary. The frequency of damage varied significantly between and within communities. The majority of trenches were not breached by elephants but five suffered ≥4 breaches. Elephant-breached trenches and their neighboring trenches were lower quality than those not breached in the same week (Wilcoxon test: p<0.001). Trenches were also more likely to be breached where people had planted more crops favored by elephants (Wilcoxon test: p = 0.014). Thus, trench quality and the draw of palatable crops both appeared to influence elephant damage. Although trenches may deter elephants, challenges include heavy labor and difficulties of digging in rocky and swampy areas. Trenches alone will not prevent conflict but this strategy holds promise for hot-spots of conflict at forest edges. Given the stakes for farmers and biodiversity, we call for systematic assessment of crop losses and offer recommendations on monitoring and analysis. Such data will allow for stronger inference about effectiveness before investment of effort and resources in interventions.
... Despite this, the illegal wildlife trade has continued to grow, facilitated by the globalisation of the world's economy, flexible border arrangements, and improved transportation [11]. Significant declines in elephant Loxondonta africana and L. cyclotis numbers [12,13] and pangolins (Order: Pholidota) [14] and the extinction of the western black rhino Diceros bicornis longipes [15] are all attributed to demand on the illegal wildlife market. Ongoing demand for illegally traded flora and fauna is driven by traditional medicines, exotic pets, and animal parts, e.g., skins, furs [3,16]. ...
The illegal wildlife trade is a significant threat to global biodiversity, often targeting already threatened species. In combating the trade, it is critical to know the provenance of the traded animal or part to facilitate targeted conservation actions, such as education and enforcement. Here, we present and compare two methods, portable X-ray fluorescence (pXRF) and stable isotope analysis (SIA), to determine both the geographic and source provenance (captive or wild) of traded animals and their parts. Using three critically endangered, frequently illegally traded Philippine species, the Palawan forest turtle (Siebenrockiella leytensis), the Philippine cockatoo (Cacatua haematuropygia), and the Philippine pangolin (Manis culionensisis), we demonstrate that using these methods, we can more accurately assign provenance using pXRF data (x¯ = 83%) than SIA data (x¯ = 47%). Our results indicate that these methods provide a valuable forensic tool that can be used in combating the illegal wildlife trade.
... Despite this, the illegal wildlife trade has continued to grow, facilitated by the globalisation of the world's economy, flexible border arrangements and improved transportation [10]. Significant declines in elephant Loxondonta africana and L. cyclotis numbers [11,12], pangolins (Order: Pholidota) [13] and the extinction of the western black rhino Diceros bicornis longipes [14] are all attributed to demand in the illegal wildlife market. Ongoing demand for illegally traded flora and fauna is driven by traditional medicines, exotic pets, and animal parts e.g. ...
The illegal wildlife trade is a significant threat to global biodiversity, often targeting already threatened species. In combating the trade, it is critical to know the provenance of the traded animal or part, to facilitate targeted conservation actions, such as education and enforcement. Here we present and compare two methods, portable X-ray fluorescence (pXRF) and stable isotope analysis (SIA), to determine both the geographic and source provenance (captive or wild) of traded animals and their parts. Using three critically endangered, frequently illegally traded Philippine species, the Palawan forest turtle (Siebenrockiella leytensis), the Philippine cockatoo (Cacatua haematuropygia), and the Philippine pangolin (Manis culionensisis) we demonstrate that using these methods we can more accurately assign provenance using pXRF data (x ̅ = 83%), than SIA data (x ̅ = 47%). Our results indicate that these methods provide a valuable forensic tool that can be used in combating the illegal wildlife trade.
... Transects across the Amboseli park boundary show a loss of plant species richness at low as well as high elephant densities due to dense woodland cover suppressing understory plants. Poulsen et al. (2017) also found elephant extirpation to result in plant species loss and ecosystem simplification in African forests. Based on the density-dependent responses of plant species richness (Figure 6), we deduce that protected area populations mask the larger shifting patchwork effect of elephants as landscape agents (Davies et al., 2018). ...
Our study monitored the changes in elephant numbers, distribution, and ecological impacts over a 50-year period. During this period, the free-ranging intermingled movements of wildlife and traditional subsistence pastoralists across the Amboseli ecosystem were disrupted by a national park, livestock ranches, farms, settlements, and changing lifestyles and economies. Elephants compressed into the national park by poaching and settlement turned woodlands to grassland and shrublands, and swamps into short grazing lawns, causing a reduction of plant and herbivore diversity and resilience to extreme events. The results echo the ecological findings of high-density elephant populations in protected areas across eastern and southern Africa. The impact has led to the view of elephants in parks as being incompatible with biodiversity and to population control measures. In contrast to Amboseli National Park, we found woody vegetation grew and plant diversity fell in areas abandoned by elephants. We therefore used naturalistic and exclosure experiments to determine the density-dependent response of vegetation to elephants. We found plant richness to peak at the park boundary where elephants and livestock jostled spatially, setting up a creative browsing-grazing tension that caused a patchwork of habitats and peak of plant richness. Prehistorical and historical literature reviews lend support to the Amboseli findings that elephants and people, the two dominant keystone species in the savannas, have been intimately entangled and coexisted prior to the global ivory trade and colonialism. The findings point to the need to view specific elephant populations in historical perspective and, as far as possible , create connectivity beyond protected areas to allow mobility on an ecosystem and landscape scale. The Amboseli study underscores the significance of space and mobility in the keystone role of elephants, and community-based conservation as a way to foster coexistence at an ecosystem and landscape scale. Space and mobility also alleviate the ecological disruption of compressed populations, and minimizes population management. K E Y W O R D S biodiversity, compression-impact, elephants and humans, keystone role, mobility, space
... Mammal habitats, especially those suitable for large fauna, are declining at rapid rates across tropical Africa. Flagship species that have been identified as likely to suffer the most dramatic population declines associated with habitat loss and degradation include great apes (Stokes et al., 2010;Junker et al., 2012;Strindberg et al., 2018) and elephants (Blake and Hedges, 2004;Blake et al., 2008;Stokes et al., 2010;Rood et al., 2010;Maisels et al., 2013;Poulsen et al., 2017Poulsen et al., , 2018. Several factors have been shown to influence the distribution of these species and the suitability of their habitat across their ranges. ...
The forests of the Congo Basin are an important home to some of the world’s most critically endangered species, including the central chimpanzee (Pan troglodytes troglodytes), the western lowland gorilla (Gorilla gorilla gorilla) and the forest elephant (Loxodanta cyclotis). To contribute to the long-term sustainability of these species and their habitats within the Dzanga Sangha Protected Areas (DSPA) in the Central African Republic, the World Wide Fund for Nature (WWF) developed an ecological monitoring program to assess the spatial drivers of species' habitat changes. Here, we assess and quantify chimpanzee, gorilla and elephant habitat suitability within the DSPA using data from two survey years (2015 and 2020), to identify priority habitat areas and recommend conservation measures to mitigate ongoing habitat changes. We found that priority chimpanzee habitats covered about 1383 km2 (30 %) of the entire DSPA in the year 2015, while priority gorilla and elephant habitats covered approximately 2569 km2 (56 %) and 3075 km2 (67 %) respectively. Priority habitat area for the three species declined by 4, 4.5 % and 9.8 % points respectively between 2015 and 2020, mostly due to increased human pressures. We further provide evidence that the Dzanga National Park represents a region of higher priority habitat for all three species owing to the reduced human pressure that has resulted from higher eco-guard patrol efforts. Based on our analysis, we recommend maintaining a nonviolent patrol presence to mitigate human pressures within remaining priority habitat areas, recognizing also the importance of collaboration with local communities to support long-term conservation goals.
... Very little information is available on the damage caused by wildlife to vegetation of African moist forest. For example, little is known about the damage caused by elephants in their biotope compared to their role as seed dispersers [55]. Some studies mentioned the damage caused by wildlife in plantations [4]. ...
Many commercial species are light-demanding and regenerate with difficulty in natural forest, which compromises the sustainability of logging. Okan, Cylicodiscus gabunensis Harms is one of the most exploited species in Central Africa and its regeneration is deficient in evergreen forest. In forest concessions, the enrichment of logging gaps with commercial species has already been tested but only for a few species. Mixed results have been obtained because the ability of seedlings to emerge from competing vegetation depends on the species, the environment and the silvicultural techniques adopted. This paper aims to determine the performance of C. gabunensis when planted in felling gaps. The impact of fertilization and biochar application on the performance of the seedlings was examined, as well as the role of predation played by large mammals. In 30 gaps, whose light levels were quantified, we planted nine seedlings and applied three treatments (fertilizer and biochar, fertilizer, control). The performance of the seedlings (survival, mammal damage and growth) was followed for 18 months. In another 30 gaps, the preferential consumption of C. gabunensis seedlings was quantified using camera traps. Seedlings had moderate and highly variable growth (1.84 cm to 2.50 cm in height and 0.201 mm to 0.267 mm in basal diameter per month, all treatments combined). Gap size and initial fertilization significantly boosted growth in diameter and survival rate. Elephants preferentially sought out C. gabunensis seedlings and after 18 months they destroyed 35% of the plants. Enrichment of logging gaps with C. gabunensis should therefore be limited to the largest gaps in forests with low elephant densities. Initial fertilization is recommended but not allowed under the sustainable management certification guidelines. We suggest that these standards should be adapted to maximize the chances of success.
... Following Hicks et al. (2014) for the same study area a proportion of nest builders of 0.83 per nest was applied (Kühl et al., 2008). Elephant defaecation rates ranged from 12.2 to 19.8 dung days -1 in CAR and Cameroon, respectively (Ruggiero, 1992;Tchamba, 1992) and decay lasted from 23.3 to 90 days in Gabon (Laguardia et al., 2021;Poulsen et al., 2017). We also applied the intermediate defaecation rate of 17 days -1 and the decay of 43.7 days to compare our estimates with those of Alers et al. (1992), who surveyed several forest areas of Zaire, now DRC. ...
Protected areas are crucial to safeguard Sub-Saharan Africa’s extraordinary and abundant
megafauna. In many of these areas, instability has derailed conservation efforts and
impeded adequate wildlife monitoring. Discovered in 2004, Eastern chimpanzees are found
in the Central Uele Basin in northern Democratic Republic of Congo (DRC) within the Bili-
Uéré Protected Areas Complex (BUPAC), the largest contiguous protected area in the
country. BUPAC is threatened by habitat destruction, mining, wild meat trade, and insecurity.
BUPAC chimpanzees are part of the largest remaining continuous population of the species
in Africa; they are also being behaviourally unique. Forest elephants were frequent in the
1960’s in the BUPAC but have declined significantly up to 2004 - 2007. We used line
transects to estimate Eastern chimpanzee and forest elephant density in the BUPAC core
area in 2016 and 2019 and compared these with the 2004-2007 surveys. A total of 37 and
137 two km long line transects were systematically placed in 5,841 km2 and 6,176 km2
survey areas in 2016 and 2019, respectively. We found that chimpanzee density did not
change during the two survey periods but indicators for forest elephant density decreased
eight-fold. Human activities were detected mainly along the core area periphery in both
survey years, where they overlapped with centres of animal activity. The stable high density
of chimpanzees is a positive outcome for the core BUPAC. However, despite being a
conservation priority area that has received relatively intensified protection, declining forest
elephant numbers are likely to reflect the high number of human conflict hotspots in vicinity
as well as the increasing human population density around the core area. We propose by
elevating the core area to National Park whilst strengthening on the ground enforcement and
management structures as well as legal measures against poaching might ensure the longterm survival of such an important area in Africa.
... Regular wildlife harvesting often necessitates the endangerment of species involved (Poulsen et al. 2017). There are 184 Parties (i.e., countries or regional economic organization) in CITES, which is supported by several nongovernmental organizations, yet poached species still decline annually in significant proportions (Challender & MacMillan 2014). ...
The global wildlife trade dates to antiquity. Recently, its harms to endangered species, animal welfare, and public health have become critical to address. The complexities of the wildlife trade are numerous, including the fact that much of the economic activity is illegal and unobserved. We find that wildlife products are used for sustenance, signaling status, medicine, and entertainment. There is vast heterogeneity in products and species traded. Supply chains extend from biodiverse, low-income regions to richer countries or urban centers. Empirically, we use data findings from the literature to rank countries in terms of intensity of the wildlife trade and identify factors that contribute to wildlife trade. We also identify supply-side and demand-side interventions that can control abuse in wildlife trade. Innovative techniques for observation, econometric analysis, and enforcement are sorely needed to support effective policies to preserve the world's wildlife.
Expected final online publication date for the Annual Review of Resource Economics, Volume 14 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... Wildlife will continue to be heavily impacted. Currently, approximately 85% of habitable land for elephants is estimated to occur outside of protected areas (Wall et al., 2021) and elephant populations are threatened by numerous human activities including habitat fragmentation, illegal hunting for ivory, and retaliatory killing for crop-raiding (Goldenberg et al., 2017;Poulsen et al., 2017). To ensure longterm population viability for the species, there is a need to be able to quantify the extent of human expansion on the continent and understand how elephants and humans coexist in shared landscapes. ...
The African savannah ecosystem is populated by nomadic pastoralists who herd livestock in the day and corral them at night in temporary enclosures, called bomas, to protect them. The number and distribution of bomas on the savan-nah is important from an ecological perspective and may have a significant impact on wildlife movement. However, no study has yet examined this relationship. Here, using very high-resolution satellite imagery from two time periods , we quanitified changes in boma distribution and density across an area of 3377 km 2 in the Laikipia-Samburu ecosystem of northern Kenya between 2011 and 2019. To assess wildlife movement in relation to bomas, we used a GPS data set on African bush elephant Loxodonta africana movement from 27 col-lared matriarchs representing herds of 9-15, covering 112 467 hourly GPS fixes over 31 months between 2018 and 2020. Our results showed a more than 46% increase in the total number of human-built structures between 2011 and 2019, the majority of which were bomas, representing a 21.9% increase in human-modified land area. Elephants readily adjusted their foraging habits and itineraries in this habitat shared with humans, who were also nomadic in space and time. Assessing the night-day activity ratio, we found elephants move more nocturnally when in closer proximity to bomas, particularly during the dry season. This temporal separation means elephants avoid the times humans are active in and around bomas while still accessing required resources-water and forage. The temporal shift was stronger during the dry season when shared resources are scarce. Using daily travel distance as a metric, we show elephants moved further in closer proximity to bomas which was likely linked to the need to travel between forage patches. Given the rise in human settlements, understanding the consequences of animals' behavioral adjustments is critical to understand the long-term population viability of elephant populations.
... where P(t) is the population at time t and P* is the population carrying capacity estimated at 1 elephant/km 2 based on conservative estimates found in the literature (48,49). The left-hand side of Eq. 1 is the per capita change in the elephant population. ...
Significance
The involvement of financial markets is critical to deliver effective and long-lasting solutions to mitigate climate change and reverse biodiversity loss. However, financial markets have not invested in ecosystem services because these are often valued based on non-market prices, which deter investments. Based on existing carbon market prices, we value the carbon services produced by forest elephants and show that wild animals’ carbon services are valuable enough to attract investors. This framework would facilitate financing of conservation programs and local communities and broaden the portfolio of nature-based solutions to mitigate climate change.
... Although such mechanistic understanding is needed, the type and resolution of data currently available make this impossible. These results do not consider other types of disturbance that are likely to affect biodiversity, but are less clearly measurable, like the loss of medium and large animals from hunting Poulsen et al., 2017bPoulsen et al., , 2018Poulsen et al., , 2021Beirne et al., 2019;Nuñez et al., 2019c). Finally, although the geographic scope of this analysis is uncommonly expansive, covering the entire country of Gabon (267,667 km 2 ), it may not be directly comparable to the diverse terrain contained in the 2,250 km 2 assessed in the Neotropics (Feeley and Silman, 2010;Maicher et al., 2021). ...
More refined knowledge of how tropical forests respond to changes in the abiotic environment is necessary to mitigate climate change, maintain biodiversity, and preserve ecosystem services. To evaluate the unique response of diverse Afrotropical forest communities to disturbances in the abiotic environment, we employ country-wide tree species inventories, remotely sensed climate data, and future climate predictions collected from 104 1-ha plots in the central African country of Gabon. We predict a 3–8% decrease in Afrotropical forest species richness by the end of the century, in contrast to the 30–50% loss of plant diversity predicted to occur with equivalent warming in the Neotropics. This work reveals that forecasts of community species composition are not generalizable across regions, and more representative studies are needed in understudied diverse biomes. This study serves as an important counterpoint to work done in the Neotropics by providing contrasting predictions for Afrotropical forests with substantially different ecological, evolutionary, and anthropogenic histories.
... The empirically based and virtual networks in our research were also resilient to removal of the socially influential group members. Given the seemingly greater flexibility and interconnectedness in elephant populations, relative to other closely knit social species [46], finding the hypothetical limitations to social resilience may require evaluating more intensive but still biologically meaningful 'poaching' disturbance than considered in our work [118]. ...
Selective harvest, such as poaching, impacts group-living animals directly through mortality of individuals with desirable traits, and indirectly by altering the structure of their social networks. Understanding the relationship between disturbance-induced, structural network changes and group performance in wild animals remains an outstanding problem. To address this problem, we evaluated the immediate effect of disturbance on group sociality in African savanna elephants-an example, group-living species threatened by poaching. Drawing on static association data from ten free-ranging groups, we constructed one empirically based, population-wide network and 100 virtual networks; performed a series of experiments 'poaching' the oldest, socially central or random individuals; and quantified the immediate change in the theoretical indices of network connectivity and efficiency of social diffusion. Although the social networks never broke down, targeted elimination of the socially central conspecifics, regardless of age, decreased network connectivity and efficiency. These findings hint at the need to further study resilience by modeling network reorganization and interaction-mediated socioecological learning, empirical data permitting. The main contribution of our work is in quantifying connectivity together with global efficiency in multiple social networks that feature the sociodemographic diversity likely found in wild elephant populations. The basic design of our simulation makes it adaptable for hypothesis testing about the consequences of anthropogenic disturbance or lethal management on social interactions in a variety of group-living species with limited, real-world data.
... And, forest elephants exhibit distinct behavioral syndromes along an axis that varies from individuals with smaller home ranges, shorter movement distances and less exploratory behavior to those with larger ranges, longer movement distances and more exploratory behavior (Beirne et al., 2021). Finally, poaching and habitat loss have drastically reduced forest elephant populations in the last two decades (Maisels et al., 2013;Poulsen et al., 2017Poulsen et al., , 2018, thus we need to understand how the reduction or loss of seed dispersal services provided by elephants could affect forest species composition. ...
By dispersing seeds long distances, large, fruit-eating animals influence plant population spread and community dynamics. After fruit consumption, animal gut passage time and movement determine seed dispersal patterns and distances. These, in turn, are influenced by extrinsic, environmental variables and intrinsic, individual-level variables. We simulated seed dispersal by forest elephants ( Loxodonta cyclotis ) by integrating gut passage data from wild elephants with movement data from 96 individuals. On average, elephants dispersed seeds 5.3 km, with 89% of seeds dispersed farther than 1 km. The longest simulated seed dispersal distance was 101 km, with an average maximum dispersal distance of 40.1 km. Seed dispersal distances varied among national parks, perhaps due to unmeasured environmental differences such as habitat heterogeneity and configuration, but not with human disturbance or habitat openness. On average, male elephants dispersed seeds farther than females. Elephant behavioral traits strongly influenced dispersal distances, with bold, exploratory elephants dispersing seeds 1.1 km farther than shy, idler elephants. Protection of forest elephants, particularly males and highly mobile, exploratory individuals, is critical to maintaining long distance seed dispersal services that shape plant communities and tropical forest habitat.
... Elephants of both extant species (Loxodonta africana and Elephas maximus) live in matriarchal fission-fusion herds of varying size in situ [1] Their complex social structures and highly related herds have been studied extensively. Populations of both species of elephant are in consistent decline due to poaching and other human-animal conflicts, as well as habitat loss and compartmentalisation of their home ranges [2][3][4]. In situ, elephants display an incredibly complex range of behaviours, showing their intelligence and social bonds which help maintain the herd dominance hierarchy required to live in such large groups. ...
Elephants are highly intelligent animals with a huge capacity for social cognition, living in large, long-lived, related herds. In captivity, it is extremely difficult to meet all of the species’ ecological needs, as well as those required individual by individual, but improvements are continually being made. After identifying impaired welfare, one collection made the decision to relocate four female African Elephants (Loxodonta africana) to a different facility. As the worlds’ largest land mammal, many safety, welfare, and logistical considerations were undertaken. The elephants travelled in two pairs, a mother–daughter pair and an older unrelated female and a younger unrelated female with a strong social bond. As a result, there was a short gap in between transports, allowing for further habituation to transport crates and the heat of summer. The changes in both social and individual behaviours of the two females remaining when their group was temporarily reduced from four to two were investigated using one-zero sampling. The study determined the daily activities of the elephants comparing ‘before transport’ to ‘after transport’ for the two remaining elephants to establish any changes in their behaviours as a result of this disturbance. Post transport, there was an increase in both human-audible vocalisations and temporal gland secretions, and hugely decreased play behaviour was observed. The dynamic between the remaining pair was also altered with more tactile behaviours from mother to daughter seen but more submission from daughter to mother. This led to the conclusion that the elephants, although mostly unrelated and living in an ‘unnatural’ captive setting, had the same signs of stress and behavioural change as would a highly related group if separated.
... A large tree can sequester proportionally more carbon than a smaller tree in a year (Stephenson et al., 2014), so loss of Forest Elephants in Central Africa will reduce the recruitment of large trees, increase stem density of smaller trees, and decrease overall carbon stocks and the rate of carbon sequestration. As much as 96% of Central African forests could have modified species composition and structure as elephants are compressed into remaining protected areas (Poulsen et al., 2017). • Recent work has suggested that the removal of megaherbivores -by humans -in the Americas 13,000 years ago, in Egypt 5000 years ago, Mesopotamia and China over 3000 years ago, and the Indus valley 1000 years ago has had the indirect effect of greatly reducing lateral nutrient transportation -especially phosphorus, a key plant nutrient -across huge areas of land, leaving vast areas with low soil nutrient levels, and the hypothesised collapse of river valley civilisations (Doughty et al., , 2016Wolf et al., 2013). ...
... A large tree can sequester proportionally more carbon than a smaller tree in a year (Stephenson et al., 2014), so loss of Forest Elephants in Central Africa will reduce the recruitment of large trees, increase stem density of smaller trees, and decrease overall carbon stocks and the rate of carbon sequestration. As much as 96% of Central African forests could have modified species composition and structure as elephants are compressed into remaining protected areas (Poulsen et al., 2017). • Recent work has suggested that the removal of megaherbivores -by humans -in the Americas 13,000 years ago, in Egypt 5000 years ago, Mesopotamia and China over 3000 years ago, and the Indus valley 1000 years ago has had the indirect effect of greatly reducing lateral nutrient transportation -especially phosphorus, a key plant nutrient -across huge areas of land, leaving vast areas with low soil nutrient levels, and the hypothesised collapse of river valley civilisations (Doughty et al., , 2016Wolf et al., 2013). ...
This study looks for the first time at the extent to which terrestrial animals protected by the Convention on the Conservation of Migratory Species of Wild Animals (CMS) are being impacted by wild meat taking, trade and consumption. It contributes to the implementation of a decision adopted by the CMS Conference of the Parties in 2020 (CMS Decision 13.109). We assessed the direct and indirect impacts of wild meat taking, trade and consumption of 105 terrestrial mammal species listed in the CMS Appendices I and II and relevant CMS daughter agreements and initiatives. We first used a systematic review of the published literature, global database searches and the IUCN Red List to determine which CMS species are affected by wild meat hunting. We then reviewed the legislation applicable to the regulation of wild meat hunting and trade and explored the application of hunting legislation using a national case-study example. Finally, we examined the known linkages between zoonotic diseases and wild meat use and trade.
... Today, forest elephants still occur in relatively moderate numbers in the dense rain forests of Gabon, Congo, and Southeast Cameroon, as well as in and around Salonga National Park in the DRC (Maisels et al., 2013). Most other populations are fragmented and have undergone dramatic declines due to commercial poaching for ivory, which has caused a population decline of over 60% (and in some sites even over 80%) over the last decade (Maisels et al., 2013;N'Goran et al., 2016;Poulsen et al., 2017). ...
Human-wildlife conflicts are ancient, but they are posing an increasing
challenge for conservation managers across Africa. Human-wildlife conflicts can lead to a loss of biodiversity and a substantial decline in human well-being, most often for
people living near protected areas . Avoiding or solving these conflicts are key issues for both protected area and wildlife managers.
... Aujourd'hui, les éléphants de forêt sont encore présents en nombre relativement modéré dans les forêts denses du Gabon, du Congo et du Sud-Est du Cameroun, ainsi que dans et autour du parc national de la Salonga, en RDC (Maisels et al., 2013). La plupart des autres populations sont fragmentées et ont connu un déclin spectaculaire en raison du braconnage commercial pour l'ivoire, qui a provoqué une chute démographique de plus de 60 % -et même de plus de 80 % dans certains sites -au cours de la dernière décennie (Maisels et al., 2013 ;N´Goran et al., 2016 ;Poulsen et al., 2017). ...
Les conflits entre l’homme et la faune sauvage sont très anciens mais ils posent
de nos jours un défi croissant aux responsables de la conservation et ce, à travers
toute l’Afrique (Lamarque et al., 2009; Nyhus, 2016; Shaffer et al., 2019). Ces conflits
peuvent entraîner une perte de la biodiversité et un déclin important du bien-être
humain, le plus souvent pour les personnes vivant à proximité des aires protégées
(Thirgood et al., 2005). Ignorer ou résoudre ces conflits constituent donc des questions
essentielles pour les gestionnaires des aires protégées et de la faune sauvage.
... However, research into forest elephant movement behavior has been limited to small sample sizes and small temporal and spatial scales, as direct observations of forest elephants are largely restricted to non-forest, open habitats that compose a small fraction of their extant range. Given the rapid rate of decline of forest elephant populations across their range (60-80% within ten years: 16,17 ), landscape-scale characterization of the drivers of movement, and its associated individual variation, is vital for the design of effective conservation and management strategies 18 , forecasting how forest elephants will cope with future environmental change 18,19 , and determining how their absence will transform tropical forest ecosystems 15 . We derive five individual-level movement behaviors from forest elephant GPS tracking data: movement distance, home range size, site fidelity, diurnality and exploratory behavior-each of which captures an important aspect of movement ecology. ...
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.
... Illegal killing of elephants in Africa for ivory has caused considerable population declines especially since the 1970s (Wasser et al. 2010;Wittemyer et al. 2014;Cerling et al. 2016;Poulsen et al. 2017) due to corruption, local poverty, and high global ivory prices (Hauenstein et al. 2019;Schlossberg et al. 2020). Indeed in 1981 when there were over a million elephants on the continent, at an IUCN African Elephant and Rhino Specialist Group (AERSG) meeting it was predicted that some elephants in Africa may not be conservable (Cumming and Jackson 1984). ...
In much of tropical Africa a breakdown in law and order, corruption and an influx of firearms led to heavy rhino and elephant poaching, especially in the 1970s and 1980s. I collected and analysed data to reveal the collapsing numbers of rhinos in Africa. Although we had general trade information, we needed more understanding of the soaring smuggling and consumption in order to combat it. I carried out extensive fieldwork in the main market at the time: North Yemen (Yemen from 1990). From the 1980s I regularly monitored the trade in rhino horn used for prestigious curved dagger (jambiya) handles, updating information on smuggling routes, prices, and demand. I worked with Yemenis on education campaigns, encouraged substitutes, and assisted policy makers, with Esmond Martin, who was to become my long- term research colleague. In the Indian subcontinent, home to most Asian rhinos, we also worked with officials and local people on strategies to fight rhino poaching and smuggling. And in eastern Asia we surveyed consumer markets for rhino horn used in traditional Oriental medicine to close down illegal trade. Around 2010 demand escalated once again causing serious rhino poaching, this time mainly in South Africa for customers in China and Vietnam, but again information was lacking. I surveyed illegal markets and collected prices of rhino horn, in order to strengthen legislation and enforcement. Demand for elephant ivory also rocketed from about 2010 onwards and we learned newly moneyed undiscerning Chinese consumers were eager to acquire mass-produced ivory items. We carried out market surveys in key illegal African and Asian markets to alert decision makers to control the surge in trafficking and unregulated retail sales, mostly for mainland Chinese. A new Chinese diaspora and the internet encouraged this lucrative trade, fuelled by corruption, mismanagement and apathy in many regions. Human population pressure on valuable natural resources is rising, resulting in climate change and wildlife crime increasing, and biodiversity in wild habitats more threatened, plus spreading zoonotic diseases. Compared with the 1980s there is at last growing attention to these challenges, including wildlife crime, in search of securing nature for a healthier, safer planet.
... Successful anti-poaching and management has resulted in the maintenance of numbers of African Forest Elephants in some localities. In other instances where protection efforts have failed, African Forest Elephant numbers have been reduced by 70% or more in a decade (ANPN, WCS, and WWF 2013;Nzooh Dongmo et al. 2016;Poulsen et al. 2017). ...
... All three species are listed in the Appendices of the Convention on International Trade in Endangered Species of Wildlife Fauna and Flora (CITES) as either critically endangered or extremely vulnerable [2,3]. Habitat fragmentation, increasing human-elephant conflict, and poaching for the illicit trade of elephant ivory, skin, and internal organs have decimated, even eliminated, entire populations of wild elephants in all traditional elephant range countries across Asia and Africa [4][5][6][7][8][9][10][11]. ...
Wild elephant populations are declining rapidly due to rampant killing for ivory and body parts, range fragmentation, and human-elephant conflict. Wild and captive elephants are further impacted by viruses, including highly pathogenic elephant endotheliotropic herpesviruses. Moreover, while the rich genetic diversity of the ancient elephant lineage is disappearing, elephants, with their low incidence of cancer, have emerged as a surprising resource in human cancer research for understanding the intrinsic cellular response to DNA damage. However, studies on cellular resistance to transformation and herpesvirus reproduction have been severely limited, in part due to the lack of established elephant cell lines to enable in vitro experiments. This report describes creation of a recombinant plasmid, pAelPyV-1-Tag, derived from a wild isolate of African Elephant Polyomavirus (AelPyV-1), that can be used to create immortalized lines of elephant cells. This isolate was extracted from a trunk nodule biopsy isolated from a wild African elephant, Loxodonta africana, in Botswana. The AelPyV-1 genome contains open-reading frames encoding the canonical large (LTag) and small (STag) tumor antigens. We cloned the entire early region spanning the LTag and overlapping STag genes from this isolate into a high-copy vector to construct a recombinant plasmid, pAelPyV-1-Tag, which effectively transformed primary elephant endothelial cells. We expect that the potential of this reagent to transform elephant primary cells will, at a minimum, facilitate study of elephant-specific herpesviruses.
... Although classified as Vulnerable by IUCN, the Elephant was not considered in this group because we assumed the scientifically well-established division in two separate species, Forest and Savanna Elephants, which have hitherto not been evaluated by IUCN. Given the precipituous decline of Forest Elephant due to poaching and its very low intrinsic growth rate the species may qualify to the Endangered or even Critically Endangered status (e.g., Cerling et al. 2016;Poulsen et al. 2017;Turkalo et al. 2017). Black-faced Impala is a subspecies considered Vulnerable, though is parental species is classified as Not Threatened. ...
Updated synthesis of the distribution and status of the mammals of Angola
... The population of African elephants (Loxodonta africana) has plummeted over the last century due to poaching, retaliatory killing from crop raiding and habitat fragmentation (Gara, 2016;Poulsen et al., 2017;Sibanda & Murwira, 2012). To ensure conservation is achieved accurate monitoring is vital. ...
Satellites allow large‐scale surveys to be conducted in short time periods with repeat surveys possible at intervals of <24 h. Very‐high‐resolution satellite imagery has been successfully used to detect and count a number of wildlife species in open, homogeneous landscapes and seascapes where target animals have a strong contrast with their environment. However, no research to date has detected animals in complex heterogeneous environments or detected elephants from space using very‐high‐resolution satellite imagery and deep learning. In this study, we apply a Convolution Neural Network (CNN) model to automatically detect and count African elephants in a woodland savanna ecosystem in South Africa. We use WorldView‐3 and 4 satellite data –the highest resolution satellite imagery commercially available. We train and test the model on 11 images from 2014 to 2019. We compare the performance accuracy of the CNN against human accuracy. Additionally, we apply the model on a coarser resolution satellite image (GeoEye‐1) captured in Kenya, without any additional training data, to test if the algorithm can generalize to an elephant population outside of the training area. Our results show that the CNN performs with high accuracy, comparable to human detection capabilities. The detection accuracy (i.e., F2 score) of the CNN models was 0.78 in heterogeneous areas and 0.73 in homogenous areas. This compares with the detection accuracy of the human labels with an averaged F2 score 0.77 in heterogeneous areas and 0.80 in homogenous areas. The CNN model can generalize to detect elephants in a different geographical location and from a lower resolution satellite. Our study demonstrates the feasibility of applying state‐of‐the‐art satellite remote sensing and deep learning technologies for detecting and counting African elephants in heterogeneous landscapes. The study showcases the feasibility of using high resolution satellite imagery as a promising new wildlife surveying technique. Through creation of a customized training dataset and application of a Convolutional Neural Network, we have automated the detection of elephants in satellite imagery with accuracy as high as human detection capabilities. The success of the model to detect elephants outside of the training data site demonstrates the generalizability of the technique. In this study, we apply a Convolution Neural Network (CNN) model to automatically detect and count African elephants in a woodland savanna ecosystem in South Africa. We use WorldView‐3 and 4 satellite data – the highest resolution satellite imagery commercially available. We compare the performance accuracy of the CNN against human accuracy generating high comparable detection performance.
... Large-bodied species are subject to higher hunting pressures as they are often favoured by hunters and are less resilient to hunting due to their slower reproductive rates (Abernethy et al., 2013). The decline of elephant, lowland gorilla, chimpanzee and yellow-backed duiker populations have already been reported in the Congo Basin (Laurance et al., 2006;Haurez et al., 2013;Poulsen et al., 2017;Kamgaing et al., 2019). In the absence of the large mammals, seed dispersal would be limited to barochory and possible short distance caching by rodents thus becoming a gregarious species as reported for other Diospyros species (Griffiths et al., 2011). ...
The Central African forest ebony, Diospyros crassiflora Hiern, is a small tree native to the moist forests of the Congo Basin. Its appealing black heartwood was one of the first products to be exported from the Gulf of Guinea in the 17th century and is today one of the main sources of ebony globally. Like for other ebony species, its commercial exploitation raises serious questions about the long-term sustainability of its trade and the viability of its populations, but the dots are yet to be joined. An examination of the interface between biology, trade, and ecology is crucial to identify the interrelated factors that could influence the potential success of its conservation. This paper reviews scientific and grey literature, forest inventories, herbarium and trade data to provide a critical assessment of the main threats to D. crassiflora populations and gaps in the current state of knowledge. It is shown here that the species is widespread but never abundant. In the longer term the species is threatened by forest conversion to agriculture and widespread hunting of large mammals on which the species rely for seed dispersal. It is currently selectively logged principally to make musical instruments and for the hongmu Chinese market, for which only one alternative black wood, the near-threatened Dalbergia melanoxylon Guill. et Perr., is commercially available. Trade statistics suggest that exports from source countries where the species is cut under the forest concession system are relatively low compared to countries like Cameroon which has seen a recent increase in exports, and where ebony is exploited without forest management plans. Logging remains a concern where the exploitation and trade of D. crassiflora are managed in response to demand rather than informed by current stock levels, growth rate and the particular reproductive biology of this species. The recent successes of private sector initiatives to ensure the long-term supply of ebony in Cameroon are promising, but would require long-term and large-scale commitments involving direct and indirect stakeholders to develop programs for the plantation and policies for the sustainable management of the species.
... The population of African elephants (Loxodonta africana) has plummeted over the last century due to poaching, retaliatory killing from crop raiding and habitat fragmentation [53][54][55]. To ensure conservation is achieved accurate monitoring is vital. ...
Satellites allow large-scale surveys to be conducted in short time periods with repeat surveys possible <24hrs. Very high-resolution satellite imagery has been successfully used to detect and count a number of wildlife species in open, homogeneous landscapes and seascapes where target animals have a strong contrast with their environment. However, no research to date has detected animals in complex heterogeneous environments or detected elephants from space using very high-resolution satellite imagery and deep learning.
In this study we apply a Convolution Neural Network (CNN) model to automatically detect and count African elephants in a woodland savanna ecosystem in South Africa. We use WorldView-3 and 4 satellite data – the highest resolution satellite imagery commercially available. We train and test the model on eleven images from 2014-2019. We compare the performance accuracy of the CNN against human accuracy. Additionally, we apply the model on a coarser resolution satellite image (GeoEye-1) captured in Kenya to test if the algorithm can generalise to an elephant population outside of the training area.
Our results show the CNN performs with high accuracy, comparable to human detection capabilities. The detection accuracy (i.e., F2 score) of the CNN models was 0.78 in heterogeneous areas and 0.73 in homogenous areas. This compares with the detection accuracy of the human labels with an averaged F2 score 0.77 in heterogeneous areas and 0.80 in homogenous areas. The CNN model can generalise to detect elephants in a different geographical location and from a lower resolution satellite.
Our study demonstrates the feasibility of applying state-of-the-art satellite remote sensing and deep learning technologies for detecting and counting African elephants in heterogeneous landscapes. The study showcases the feasibility of using high resolution satellite imagery as a promising new wildlife surveying technique. Through creation of a customised training dataset and application of a Convolutional Neural Network, we have automated the detection of elephants in satellite imagery with as high accuracy as human detection capabilities. The success of the model to detect elephants outside of the training data site demonstrates the generalisability of the technique.
... Thus, any weakening of enforcement due to declining funding may increase incentives to hunt, thereby further threatening the often rare and endangered, or particularly abundant, fauna that a given Protected Area was set up to conserve. In Ghana the Kakum rainforest in the south and Mole National Park in the north of the country might be Protected Areas of particular concern, while in Gabon Minkebe NP might be particularly at risk from commercial poaching if enforcement is reduced (Poulsen et al. 2017). ...
Wild animals play an integral and complex role in the economies and ecologies of many countries across the globe, including those of West and Central Africa, the focus of this policy perspective. The trade in wild meat, and its role in diets, have been brought into focus as a consequence of discussions over the origins of COVID-19. As a result, there have been calls for the closure of China’s “wet markets”; greater scrutiny of the wildlife trade in general; and a spotlight has been placed on the potential risks posed by growing human populations and shrinking natural habitats for animal to human transmission of zoonotic diseases. However, to date there has been little attention given to what the consequences of the COVID-19 economic shock may be for the wildlife trade; the people who rely on it for their livelihoods; and the wildlife that is exploited. In this policy perspective, we argue that the links between the COVID-19 pandemic, rural livelihoods and wildlife are likely to be more complex, more nuanced, and more far-reaching, than is represented in the literature to date. We develop a causal model that tracks the likely implications for the wild meat trade of the systemic crisis triggered by COVID-19. We focus on the resulting economic shockwave, as manifested in the collapse in global demand for commodities such as oil, and international tourism services, and what this may mean for local African economies and livelihoods. We trace the shockwave through to the consequences for the use of, and demand for, wild meats as households respond to these changes. We suggest that understanding and predicting the complex dynamics of wild meat use requires increased collaboration between environmental and resource economics and the ecological and conservation sciences.
... In Western Africa, most savannah elephant populations are small and isolated, meaning that these populations could be at risk of extirpation 4 . In Central Africa, studies have shown major declines in some elephant populations 5,20 . Recent survey data from Southern Africa is limited, but two major elephant populations in this region are showing worrisome trends. ...
The most comprehensive data on poaching of African elephants comes from the Monitoring the Illegal Killing of Elephants (MIKE) program, which reports numbers of illegally killed carcasses encountered by rangers. Recent studies utilizing MIKE data have reported that poaching of African elephants peaked in 2011 and has been decreasing through 2018. Closer examination of these studies, however, raises questions about the conclusion that poaching is decreasing throughout the continent. To provide more accurate information on trends in elephant poaching, we analyzed MIKE data using state-space models. State-space models account for missing data and the error inherent when sampling carcasses. Using the state-space model, for 2011–2018, we found no significant temporal trends in rates of illegal killing for Southern, Central and Western Africa. Only in Eastern Africa have poaching rates decreased substantially since 2011. For Africa as a whole, poaching did decline for 2011–2018, but the decline was entirely due to Eastern African sites. Our results suggest that poaching for ivory has not diminished across most of Africa since 2011. Continued vigilance and anti-poaching efforts will be necessary to combat poaching and to conserve African elephants.
... While not the sole dispersers for most tropical seeds, the distance and quantity of seeds moved by forest elephants supersedes most other species (Bunney et al., 2017). Loss of elephant dispersal from poaching or habitat loss (Poulsen et al., 2017) could lead to reduced forest diversity, inability of forests to colonize new or deforested areas, and potentially reduced carbon stocks (Nathan, 2006;Jordano et al., 2007;Poulsen et al., 2018;Berzaghi et al., 2019). ...
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.
... Hypothesis 4: Distance to international border.-Foreign poaching gangs have been implicated in recent elephant massacres, and cross-border poaching can occur where law enforcement is not coordinated between neighboring countries (Poulsen et al. 2017). More generally, conditions in neighboring countries can affect a country's elephant populations (Frank and Maurseth 2006). ...
Populations of African savannah elephants (Loxodonta africana) have been declining due to poaching, human‐elephant conflict, and habitat loss. Understanding the causes of these declines could aid in stabilizing elephant populations. We used data from the Great Elephant Census, a 19‐country aerial survey of savannah elephants conducted in 2014 and 2015, to examine effects of a suite of variables on elephant mortality. Independent variables included spatially explicit measures of natural processes and human presence as well as country‐level socioeconomic measures. Our dependent variable was the carcass ratio, the ratio of dead elephants to live plus dead elephants, which is an index of recent elephant mortality. Carcass ratios are inversely proportional to population growth rates of elephants over the four years prior to a survey. At the scale of survey strata (n = 275, median area = 1,222 km2), we found strong negative associations for carcass ratios with vegetation greenness at the time of the survey, overseas development aid to the country, and distance to the nearest international border. At the scale of ecosystems (n = 42, median area = 12,085 km2), carcass ratios increased with drought frequency and decreased with human density and overseas development aid to the country. Both stratum‐ and ecosystem‐scale models explained well under half of the variance in carcass ratios. The differences in results between scales suggest that the drivers of mortality may be scale‐specific and that the corresponding solutions may vary by scale as well.
... Probably more importantly, the Ituri forest may be recovering from past disturbances, as many other African forests (van Gemerden et al. 2003, Willis et al. 2004, Brncic et al. 2007, Lewis et al. 2009). The increased poaching (Effiom et al. 2013) and the strong reduction in forest elephants (Beyers et al. 2011, Poulsen et al. 2017) is leading to less browsing and damage and a closing forest (C. E. N. Ewango, personal observation). ...
Lianas, woody climbing plants, are increasing in many tropical forests, with cascading effects such as decreased forest productivity, carbon sequestration, and resilience. Possible causes are increasing forest fragmentation, CO2 fertilization, and drought. Determining the primary changing species and their underlying vital rates help explain the liana trends. We monitored over 17,000 liana stems for 13 years in 20 ha of old-growth forest in the Congo Basin, and here we report changes and vital rates for the community and for the 87 most abundant species. The total liana abundance declined from 15007 lianas in 1994 to 11090 in 2001 to 9978 in 2007. Over half (52%) of the evaluated species have significantly declining populations, showing that the community response is not the result of changes in a few dominant species only. Species density change (i.e. the change in number of individuals per ha) decreased with mortality rate, tended to increase with recruitment rate but was independent of growth rate. Species change was independent of functional characteristics important for plant responses to fragmentation, CO2 and drought, such as lifetime light requirements, climbing- and dispersal mechanism, and of leaf size. These results indicate that in Congo lianas do not show the reputed global liana increase, but rather a decline, and that elements of the reputed drivers underlying global liana change do not apply to this DR Congo forest. We suggest warfare in the Congo Basin to have decimated the elephant population, leading to less disturbance, forest closure and declining liana numbers. Our results imply that, in this tropical forest, local causes (i.e. disturbance) override more global causes of liana change resulting in liana decline, which sharply contrasts with the liana increase observed elsewhere.
... We have little understanding of the degree to which elephants drive this phenomenon, though they might play a strong role in distinguishing African forests from Neotropical forests (Poulsen et al., 2018;Terborgh et al., 2016aTerborgh et al., , 2016b exclosures to isolate the specific ecological effects of elephants. Given their dramatic population declines (Maisels et al., 2013;Poulsen et al., 2017), research focused on African forest elephants has both ecological and conservation merit, and will lead to an improved understanding of the factors that shape and maintain these ecosystems. ...
African forest elephants ( Loxodonta cyclotis ) are ecosystem engineers that browse and damage large quantities of vegetation during their foraging and movement. Though elephant trail networks and clearings are conspicuous features of many African forests, the consequences of elephant foraging for forest structure and diversity are poorly documented. In this study in northeastern Gabon, we compare stem size, stem density, proportional damage, species diversity, and species relative abundance of seedlings and saplings in the vicinity of seven tree species that produce elephant‐preferred fruits (“elephant trees”) relative to control trees that do not. Across 34 survey trees, with a combined census area of 2.04 ha, we recorded data on 26,128 woody stems in three sizes classes. Compared with control trees, the area around elephant trees had the following: (a) a significantly greater proportion of damaged seedlings and a marginally greater proportion of damaged saplings (with 82% and 24% greater odds of damage, respectively); (b) no significant difference in stem density or species diversity; and (c) a significantly greater relative abundance of seedlings of elephant tree species. Increasing distance away from focal elephant trees was associated with significantly reduced sapling stem damage, significantly increased sapling stem density, and significantly increased sapling species diversity. Considered in sum, our results suggest that elephants can affect the structure and diversity of Afrotropical forests through their foraging activities, with some variation based on location and plant size class. Developing a more complete understanding of elephants’ ecological effects will require continued research, ideally with manipulative experiments.
Abstract in French is available with online material.
With a drastic decrease in their populations over the last decades, forest elephants Loxodonta cyclotis are facing increasing human pressure. Their decline will have serious ecological consequences, as they are key actors in shaping ecosystems. Whilst timber concessions host many mammal species, the interactions between selective logging and forest elephants remain unclear.
Through an extensive literature review, we discussed the following: 1) the ecological and human factors that drive the distribution of forest elephants on a large scale as well as in the specific context of logged forests; 2) the contribution of forest elephants to the regeneration of timber species; and 3) the damage caused by forest elephants to timber species.
Although human activities have the greatest impact on forest elephant distribution, it is the availability of food, water, and minerals that locally determines their use of the habitat. Under specific conditions, timber concessions may host large populations of forest elephants.
As effective seed dispersers, forest elephants contribute to the regeneration of at least 41 timber species, such as Bobgunnia fistuloides (pao rosa), one of the most expensive woods on the market.
Damage caused by forest elephants is diverse and affects a wide range of species. From branch breaking to bark stripping, at least 61 timber species are used by forest elephants, and little is known about the consequences for the tree's vitality and wood quality.
The interactions between forest elephants and logging are complex and involve many variables, requiring additional research. Nevertheless, this review suggests that timber concessions constitute key areas for forest elephant conservation, provided that low‐impact logging and wildlife management are implemented.
Background and Research Aim
African forest elephants ( Loxodonta cyclotis) are critically endangered yet research on factors influencing their resource use is limited in Central Africa. We assessed the influence of fruit availability, land use types, and anthropogenic activity on forest elephant presence and relative abundance in the southwest part of the Campo-Ma’an Technical Operational Unit (CMTOU) to better understand elephant habitat use in human dominated systems and inform elephant management strategies.
Methods
We used 17 camera trap stations and surveyed 17 line transects to monitor forest elephant presence and relative abundance as a function of fruit availability, tree species richness, and land use types. Our study area spanned a gradient of human disturbance and included a National Park (NP), Forest Management Unit (FMU), and Community Land (CL).
Results
Forest elephants were more likely to occur in areas with increased fruit availability and tree species richness. Also, the likelihood of their presence was higher in CL than in FMU and NP. Elephant relative abundance was negatively affected by human activities such as hunting and logging. The relationship between elephant relative abundance and fruit availability was stronger in CL and NP as compared to the FMU. Elephant relative abundance was higher during the rainy season.
Conclusion
Forest elephant habitat use was positively affected by fruit availability across land use types, and negatively affected by human activities in the southwest part of the CMTOU.
Implications for Conservation
Continued monitoring of elephant responses to food availability in CMTOU is warranted to track changes in elephant habitat use. Knowledge of the distribution of fruiting trees consumed by forest elephants may allow managers to predict hotspots of habitat use, and to therefore develop effective management strategies.
The emergence of social media in the twenty-first century revolutionized the production and consumption of information, offering opportunities that were never imagined in the past centuries. A simple account in any of the social media sites allows one to produce and disseminate information timeously with little or no regulation at a low cost. While this development can be celebrated as an alternative source of information to that of private and public media houses which had enjoyed an unparalleled monopoly on the production and consumption of information, it has brought with it a burden of undesired consequences. With its ability to shape public discourse, social media has not only led to the dismantling of autocratic regimes that was witnessed in the Arab Springs or the so-called Twitter Revolutions, but also to well-coordinated ethnic hate crimes and xenophobic attitudes premised on nationalism or nativism. For instance, Bursztyn et al. (2019b) illustrate how social media contributed to the young Russian people’s xenophobic attitudes. Beyond this, social media also plays a pivotal role through its ability to disseminate misinformation, disinformation, distortion, lies, and fake news and the coordination of crimes as an expression of xenophobic attitudes. However, there is a dearth of scholarly literature on the nexus between social media and xenophobic attitudes and violence in Africa. As a result, our knowledge on this matter is mostly based on anecdotal evidence and mere speculation. It is against this background and the broader aim of the book that this chapter seeks to explore the role of social media in inciting and fanning xenophobia in Africa. Using an in-depth analysis of literature as well as social media information, the chapter demonstrates how social media acts as a catalyst in bringing together cognitive, environmental, and personal factors to produce xenophobic attitudes and behavior that are mainly based on nativism and nationalism.
Nearly five decades after the creation of the Central African Customs and Economic Union (UDEAC) and about four decades since the establishment of the Economic Community of Central African States (ECCAS), countries in the Central Africa region are still not enjoying the benefits of regional integration, such as trade and investment opportunities, broader markets, increased bargaining power, and freer movement of persons and goods. While recognizing that this state of affairs results from several factors, this chapter focuses on xenophobia – showing how it has contributed to slowing the regional integration scheme in the region. It concludes by positing that for regional groupings in the Central African region to take full advantage of new opportunities the recently launched African Continental Free Trade Area offers, they need to address pre-existing challenges plaguing their functioning, including xenophobia.
This edited volume systematically analyzes the connection between xenophobia, nativism, and Pan-Africanism. It situates attacks on black Africans by fellow black Africans within the context of ideals such as Pan-Africanism and Ubuntu, which emphasize unity. The book straddles a range of social science perspectives to explain why attacks on foreign nationals in Africa usually entail attacks on black foreign nationals. Written by an international and interdisciplinary team of scholars, the book is divided into four sections that each explain a different facet of this complicated relationship.
Section One discusses the history of colonialism and apartheid and their relationship to xenophobia. Section Two critically evaluates Pan-Africanism as a concept and as a practice in 21st century Africa. Section Three presents case studies on xenophobia in contemporary Africa. Section Four similarly discusses cases of nativism.
Addressing a complex issue in contemporary African politics, this volume will be of use to students and scholars interested in African studies, African politics, human rights, migration, history, law, and development economics.
Robust monitoring programs are essential for understanding changes in wildlife population dynamics and distribution over time, especially for species of conservation concern. In this study, we applied a rapid non-invasive sampling approach to the Critically Endangered African forest elephant (Loxodonta cyclotis), at nationwide scale in its principal remaining population strongholds in Gabon. We used a species-specific customized genetic panel and spatial capture-recapture (SCR) approach, which gave a snapshot of current abundance and density distribution of forest elephants across the country. We estimated mean forest elephant density at 0.38 (95% Confidence Interval 0.24–0.52) per km² from 18 surveyed sites. We confirm that Gabon is the main forest elephant stronghold, both in terms of estimated population size: 95,110 (95% CI 58,872–131,349) and spatial distribution (250,782 km²). Predicted elephant densities were highest in relatively flat areas with a high proportion of suitable habitat not in proximity to the national border. Protected areas and human pressure were not strong predictors of elephant densities in this study. Our nationwide systematic survey of forest elephants of Gabon serves as a proof-of-concept of application of noninvasive genetic sampling for rigorous population monitoring at large spatial scales. To our knowledge, it is the first nationwide DNA-based assessment of a free-ranging large mammal in Africa. Our findings offer a useful national baseline and status update for forest elephants in Gabon. It will inform adaptive management and stewardship of elephants and forests in the most important national forest elephant stronghold in Africa.
This paper uses qualitative research methods guided by the social exchange theory and the Community-Based Natural Resource Management concept to explore the contribution of community-based ecotourism to bushmeat consumption/production using the Chobe Enclave Conservation Trust, located adjacent to the Chobe National Park, Botswana. Data were collected between May and August 2018. Using semi-structured in-depth interviews, results indicate that, bushmeat consumption became prevalent through trophy hunting tourism. With the hunting ban in 2014, game hunting licenses was stopped, cutting institutionalized bushmeat supply and widening trade-offs between community livelihoods improvement and conservation. Socially, hunting tourism has contributed to affinity for bushmeat taste. Bushmeat contributes to food security for a significant number of community members. Institutionally, bushmeat’s contribution to community livelihoods is perceived varyingly by different stakeholders - some see it as a threat to wildlife resources, a key driver to poaching and extinction of species resulting in unmanageable stakeholders’ interests while others see it as a means to improve their livelihoods and dietary needs. Overall, the nutritional role and financial contribution of bushmeat are prevalent in rural people's livelihoods. The paper contributes through the development of a model that aims to improve bushmeat production and community participation in natural resources conservation
This report (the first of two parts) is the result of a study on the interaction between security and wildlife conservation in Sub Saharan Africa commissioned by the European Commission (DG International Cooperation and Development). The study was conducted in 2017 and consisted of a desk review and field research in 11 selected sites across Sub Saharan Africa (case studies). Part I of the report provides the results from the analysis, conclusions and recommendations, Part II contains the reports of the case studies.
Elephants are the largest extant terrestrial animals and are important for maintaining regional ecosystem balance and community diversity. However, poaching, population growth, habitat fragmentation, and viruses are major threats to global elephant populations. Foot-and-mouth disease (FMD) is one of the major threats to the health of elephants. Global warming has a serious impact on wildlife and accelerates the spread of viruses. In this study, the effects of climate change on the risk of disease in elephants were evaluated based on 1,833 sites with reported FMD cases. Maximum entropy (MaxEnt) was used to model the current and future geographic distributions of FMD and to assess the risk of FMD in elephants under climate change. The results showed that the average annual temperature and annual precipitation were higher in elephant habitats than in the range of the FMD virus. The mean temperature in the driest quarter, temperature seasonality, annual mean temperature, and precipitation in the driest month had relatively large contributions to the risk of FMD, with a cumulative contribution rate of 82.8%. Both Asian elephants and African elephants had high overlap with the FMD virus with respect to altitude, annual mean temperature, and annual precipitation. An overall high risk of disease was detected at a certain band, mainly concentrated from 10°N to 50°N in the northern hemisphere and from 10°S to 35°S in the southern hemisphere. The risk of FMD was higher for the Asian elephant than the African elephant. The FMD risk increased gradually from the southeast to northwest in habitats of the Asian elephant, and presented a pattern of high north–south risk and low intermediate risk in the habitats of the African elephant. The area proportions of high risk, medium risk, and low risk in the distribution of both the Asian elephant and African elephant were all higher than the proportions of all risk types worldwide. Under global warming, the FMD risk was not expected to change significantly in most of the habitat areas of the Asian elephant or the African elephant in the 2050s and 2070s. Moreover, the areas and proportions of high risk, medium risk, and low risk were likely to change slightly. These results could benefit the conservation of elephants and provide relevant data for the prevention of FMD in high-risk areas under climate change.
This book provides the first contemporary assessment of area-based conservation and its implications for nature and society. Now covering 15 per cent of the land surface and a growing area of ocean, the creation of protected areas is one of the fastest conscious changes in land management in history. But this has come at a cost, including a backlash from human rights organisations about the social impacts of protected areas. At the same time, a range of new types of area-based conservation has emerged, based on indigenous people's territories, local community lands and a new designation of "other effective area-based conservation measures". This book provides a concise overview of the status and possible futures of area-based conservation. With many people calling for half the earth's land surface to remain in a natural condition, this book taps into the urgent debate about the feasibility of such an aim and the ways in which such land might be managed. It provides a timely contribution by people who have been at the centre of the debate for the last twenty years. Building on the authors' large personal knowledge, the book draws on global case studies where the authors have firsthand experience, including Yosemite National Park (USA), Blue Mountains National Park (Australia), Bwindi National Park (Uganda), Chingaza National Park (Colombia), Ustyart Plateau (Kazakhstan), Snowdonia National Park (Wales) and many more. This book is essential reading for students, academics and practitioners interested in conservation and its impact on society.
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 north‐eastern 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 programmes 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.
1. Faecal counting techniques were used to census five large mammalian herbivores during 1988 and 1989 in the Parc National des Volcans in Rwanda. These five herbivores were the black-fronted duiker (Cephalophus nigrifrons), the bushbuck (Tragelaphus scriptus), the Cape buffalo (Syncerus caffer), the mountain gorilla (Gorilla gorilla beringei) and the African elephant (Loxodonta africana). 2. Population density estimations from standing crop counts of faeces usually correct the counts for the defecation rate of the animal and the decomposition rate of the dung, assuming that the decay of the dung is constant. However, this study found that the dung decay was not constant. For bushbucks, exponential decay curves were found in the wet seasons and sigmoidal decay curves in the dry seasons. Only sigmoidal curves were found for buffalos and elephants. Therefore, measures of dung decomposition throughout the year were used in a computer model which estimated iteratively the population density. 3. Ecological density estimates were obtained for eight habitat types found in the Park. Habitats at the summit of volcanos sustain the lowest biomass of large herbivores at 10-15 kg ha-1 whilst meadows sustain the highest biomass at 45-50 kg ha-1. The biomass for the whole study area was calculated as 31 kg ha-1, one of the highest biomasses for any forest yet studied. The bushbuck and the buffalo dominated this biomass. The implications of this for the conservation of the mountain gorilla are discussed and it is concluded that currently these animals have little impact on the gorilla's food supply.
Significance
Illegal harvest for commercial trade has recently surged to become a major threat to some of the world’s most endangered and charismatic species. Unfortunately, the cryptic nature of illegal killing makes estimation of rates and impacts difficult. Applying a model based on field census of carcasses, to our knowledge we provide the first detailed assessment of African elephant illegal killing rates at population, regional, and continental scales. Illegal harvest for commercial trade in ivory has recently surged, coinciding with increases in illegal ivory seizures and black market ivory prices. As a result, the species declined over the past 4 y, during which tens of thousands of elephants have been killed annually across the continent. Solutions to this crisis require global action.
Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. The Elephant Trade Information System, a global database of reported seizures of illegal ivory, holds the only extensive information on illicit trade available. However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured. We developed a new modelling framework to provide quantitative evidence on trends in the illegal ivory trade from seizures data. The framework used Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time. Models produced bias-adjusted smoothed estimates of relative trends in illegal ivory activity for raw and worked ivory in three weight classes. Activity is represented by two indicators describing the number of illegal ivory transactions - Transactions Index - and the total weight of illegal ivory transactions - Weights Index - at global, regional or national levels. Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg mainly moving from Central and East Africa to Southeast and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants.
African forest elephants- taxonomically and functionally unique-are being poached at accelerating rates, but we lack range-wide information on the repercussions. Analysis of the largest survey dataset ever assembled for forest elephants (80 foot-surveys; covering 13,000 km; 91,600 person-days of fieldwork) revealed that population size declined by ca. 62% between 2002-2011, and the taxon lost 30% of its geographical range. The population is now less than 10% of its potential size, occupying less than 25% of its potential range. High human population density, hunting intensity, absence of law enforcement, poor governance, and proximity to expanding infrastructure are the strongest predictors of decline. To save the remaining African forest elephants, illegal poaching for ivory and encroachment into core elephant habitat must be stopped. In addition, the international demand for ivory, which fuels illegal trade, must be dramatically reduced.
This book is available for purchase, The 1993 version is available on the page at
http://distancesampling.org/whatisds.html
1. Species distribution models are increasingly used to address questions in conservation biology, ecology and evolution. The most effective species distribution models require data on both species presence and the available environmental conditions (known as background or pseudo-absence data) in the area. However, there is still no consensus on how and where to sample these pseudo-absences and how many.
2. In this study, we conducted a comprehensive comparative analysis based on simple simulated species distributions to propose guidelines on how, where and how many pseudo-absences should be generated to build reliable species distribution models. Depending on the quantity and quality of the initial presence data (unbiased vs. climatically or spatially biased), we assessed the relative effect of the method for selecting pseudo-absences (random vs. environmentally or spatially stratified) and their number on the predictive accuracy of seven common modelling techniques (regression, classification and machine-learning techniques).
3. When using regression techniques, the method used to select pseudo-absences had the greatest impact on the model’s predictive accuracy. Randomly selected pseudo-absences yielded the most reliable distribution models. Models fitted with a large number of pseudo-absences but equally weighted to the presences (i.e. the weighted sum of presence equals the weighted sum of pseudo-absence) produced the most accurate predicted distributions. For classification and machine-learning techniques, the number of pseudo-absences had the greatest impact on model accuracy, and averaging several runs with fewer pseudo-absences than for regression techniques yielded the most predictive models.
4. Overall, we recommend the use of a large number (e.g. 10 000) of pseudo-absences with equal weighting for presences and absences when using regression techniques (e.g. generalised linear model and generalised additive model); averaging several runs (e.g. 10) with fewer pseudo-absences (e.g. 100) with equal weighting for presences and absences with multiple adaptive regression splines and discriminant analyses; and using the same number of pseudo-absences as available presences (averaging several runs if few pseudo-absences) for classification techniques such as boosted regression trees, classification trees and random forest. In addition, we recommend the random selection of pseudo-absences when using regression techniques and the random selection of geographically and environmentally stratified pseudo-absences when using classification and machine-learning techniques.
1.Distance sampling is a widely used technique for estimating the size or density of biological populations. Many distance sampling designs and most analyses use the software Distance.
2.We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distance, and provide hints on its use.
3.Good survey design is a crucial prerequisite for obtaining reliable results. Distance has a survey design engine, with a built-in geographic information system, that allows properties of different proposed designs to be examined via simulation, and survey plans to be generated.
4.A first step in analysis of distance sampling data is modelling the probability of detection. Distance contains three increasingly sophisticated analysis engines for this: conventional distance sampling, which models detection probability as a function of distance from the transect and assumes all objects at zero distance are detected; multiple-covariate distance sampling, which allows covariates in addition to distance; and mark–recapture distance sampling, which relaxes the assumption of certain detection at zero distance.
5.All three engines allow estimation of density or abundance, stratified if required, with associated measures of precision calculated either analytically or via the bootstrap.
6.Advanced analysis topics covered include the use of multipliers to allow analysis of indirect surveys (such as dung or nest surveys), the density surface modelling analysis engine for spatial and habitat modelling, and information about accessing the analysis engines directly from other software.
7.Synthesis and applications. Distance sampling is a key method for producing abundance and density estimates in challenging field conditions. The theory underlying the methods continues to expand to cope with realistic estimation situations. In step with theoretical developments, state-of-the-art software that implements these methods is described that makes the methods accessible to practising ecologists.
Collinearity refers to the non independence of predictor variables, usually in a regression-type analysis. It is a common feature of any descriptive ecological data set and can be a problem for parameter estimation because it inflates the variance of regression parameters and hence potentially leads to the wrong identification of relevant predictors in a statistical model. Collinearity is a severe problem when a model is trained on data from one region or time, and predicted to another with a different or unknown structure of collinearity. To demonstrate the reach of the problem of collinearity in ecology, we show how relationships among predictors differ between biomes, change over spatial scales and through time. Across disciplines, different approaches to addressing collinearity problems have been developed, ranging from clustering of predictors, threshold-based pre-selection, through latent variable methods, to shrinkage and regularisation. Using simulated data with five predictor-response relationships of increasing complexity and eight levels of collinearity we compared ways to address collinearity with standard multiple regression and machine-learning approaches. We assessed the performance of each approach by testing its impact on prediction to new data. In the extreme, we tested whether the methods were able to identify the true underlying relationship in a training dataset with strong collinearity by evaluating its performance on a test dataset without any collinearity. We found that methods specifically designed for collinearity, such as latent variable methods and tree based models, did not outperform the traditional GLM and threshold-based pre-selection. Our results highlight the value of GLM in combination with penalised methods (particularly ridge) and threshold-based pre-selection when omitted variables are considered in the final interpretation. However, all approaches tested yielded degraded predictions under change in collinearity structure and the ‘folk lore’-thresholds of correlation coefficients between predictor variables of |r| >0.7 was an appropriate indicator for when collinearity begins to severely distort model estimation and subsequent prediction. The use of ecological understanding of the system in pre-analysis variable selection and the choice of the least sensitive statistical approaches reduce the problems of collinearity, but cannot ultimately solve them.
Protected areas are fundamental to biodiversity conservation, but there is growing recognition of the need to extend beyond protected areas to meet the ecological requirements of species at larger scales. Landscape-scale conservation requires an evaluation of management impact on biodiversity under different land-use strategies; this is challenging and there exist few empirical studies. In a conservation landscape in northern Republic of Congo we demonstrate the application of a large-scale monitoring program designed to evaluate the impact of conservation interventions on three globally threatened species: western gorillas, chimpanzees and forest elephants, under three land-use types: integral protection, commercial logging, and community-based natural resource management. We applied distance-sampling methods to examine species abundance across different land-use types under varying degrees of management and human disturbance. We found no clear trends in abundance between land-use types. However, units with interventions designed to reduce poaching and protect habitats--irrespective of land-use type--harboured all three species at consistently higher abundance than a neighbouring logging concession undergoing no wildlife management. We applied Generalized-Additive Models to evaluate a priori predictions of species response to different landscape processes. Our results indicate that, given adequate protection from poaching, elephants and gorillas can profit from herbaceous vegetation in recently logged forests and maintain access to ecologically important resources located outside of protected areas. However, proximity to the single integrally protected area in the landscape maintained an overriding positive influence on elephant abundance, and logging roads--even subject to anti-poaching controls--were exploited by elephant poachers and had a major negative influence on elephant distribution. Chimpanzees show a clear preference for unlogged or more mature forests and human disturbance had a negative influence on chimpanzee abundance, in spite of anti-poaching interventions. We caution against the pitfalls of missing and confounded co-variables in model-based estimation approaches and highlight the importance of spatial scale in the response of different species to landscape processes. We stress the importance of a stratified design-based approach to monitoring species status in response to conservation interventions and advocate a holistic framework for landscape-scale monitoring that includes smaller-scale targeted research and punctual assessment of threats.
1. The biases and shortcomings of stepwise multiple regression are well established within the statistical literature. However, an examination of papers published in 2004 by three leading ecological and behavioural journals suggested that the use of this technique remains widespread: of 65 papers in which a multiple regression approach was used, 57% of studies used a stepwise procedure. 2. The principal drawbacks of stepwise multiple regression include bias in parameter estimation, inconsistencies among model selection algorithms, an inherent (but often overlooked) problem of multiple hypothesis testing, and an inappropriate focus or reliance on a single best model. We discuss each of these issues with examples. 3. We use a worked example of data on yellowhammer distribution collected over 4 years to highlight the pitfalls of stepwise regression. We show that stepwise regression allows models containing significant predictors to be obtained from each year's data. In spite of the significance of the selected models, they vary substantially between years and suggest patterns that are at odds with those determined by analysing the full, 4-year data set. 4. An information theoretic (IT) analysis of the yellowhammer data set illustrates why the varying outcomes of stepwise analyses arise. In particular, the IT approach identifies large numbers of competing models that could describe the data equally well, showing that no one model should be relied upon for inference.
Author Summary
Forest elephants, perhaps a distinct species of African elephant, occur in the forests of West and Central Africa. Compared to the more familiar savannah elephant of Eastern and Southern Africa, forest elephant biology and their conservation status are poorly known. To provide robust scientific data on the status and distribution of forest elephants to inform and guide conservation efforts, we conducted surveys on foot of forest elephant abundance and of illegal killing of elephants in important conservation sites throughout Central Africa. We covered a combined distance of over 8,000 km on reconnaissance walks, and we systematically surveyed a total area of some 60,000 km2 under the auspices of the Monitoring of the Illegal Killing of Elephants (MIKE) programme. Our results indicate that forest elephant numbers and range are severely threatened by hunting for ivory. Elephant abundance increased with increasing distance from the nearest road, and poaching pressure was most concentrated near roads. We found that protected areas have a positive impact on elephant abundance, probably because management interventions reduced poaching rates inside protected areas compared to non-protected forest. Law enforcement to bring the illegal ivory trade under control, and effective management and protection of large and remote national parks will be critical if forest elephants are to be successfully conserved.
Tools for performing model selection and model averaging. Automated model selection through subsetting the maximum model, with optional constraints for model inclusion. Model parameter and prediction averaging based on model weights derived from information criteria (AICc and alike) or custom model weighting schemes.
[Please do not request the full text - it is an R package. The up-to-date manual is available from CRAN].
The first edition of this book has established itself as one of the leading references on generalized additive models (GAMs), and the only book on the topic to be introductory in nature with a wealth of practical examples and software implementation. It is self-contained, providing the necessary background in linear models, linear mixed models, and generalized linear models (GLMs), before presenting a balanced treatment of the theory and applications of GAMs and related models. The author bases his approach on a framework of penalized regression splines, and while firmly focused on the practical aspects of GAMs, discussions include fairly full explanations of the theory underlying the methods. Use of R software helps explain the theory and illustrates the practical application of the methodology. Each chapter contains an extensive set of exercises, with solutions in an appendix or in the book’s R data package gamair, to enable use as a course text or for self-study.
Poaching of elephants is now occurring at rates that threaten African populations with extinction. Identifying the number and location of Africa's major poaching hotspots may assist efforts to end poaching and facilitate recovery of elephant populations. We genetically assign origin to 28 large ivory seizures (≥0.5 tons) made between 1996-2014, also testing assignment accuracy. Results suggest that the major poaching hotspots in Africa may be currently concentrated in as few as two areas. Increasing law enforcement in these two hotspots could help curtail future elephant losses across Africa and disrupt this organized transnational crime.
Copyright © 2015, American Association for the Advancement of Science.
Our understanding of a biological population can be greatly enhanced by modelling their distribution in space and as a function of environmental covariates. Such models can be used to investigate the relationships between distribution and environmental covariates as well as reliably estimate abundances and create maps of animal/plant distribution.
Density surface models consist of a spatial model of the abundance of a biological population which has been corrected for uncertain detection via distance sampling methods.
We review recent developments in the field and consider the likely directions of future research before focussing on a popular approach based on generalized additive models. In particular, we consider spatial modelling techniques that may be advantageous to applied ecologists such as quantification of uncertainty in a two-stage model and smoothing in areas with complex boundaries.
The methods discussed are available in an R package developed by the authors (dsm) and are largely implemented in the popular Windows software Distance.
Ecological Models and Data in R is the first truly practical introduction to modern statistical methods for ecology. In step-by-step detail, the book teaches ecology graduate students and researchers everything they need to know in order to use maximum likelihood, information-theoretic, and Bayesian techniques to analyze their own data using the programming language R. Drawing on extensive experience teaching these techniques to graduate students in ecology, Benjamin Bolker shows how to choose among and construct statistical models for data, estimate their parameters and confidence limits, and interpret the results. The book also covers statistical frameworks, the philosophy of statistical modeling, and critical mathematical functions and probability distributions. It requires no programming background--only basic calculus and statistics. Practical, beginner-friendly introduction to modern statistical techniques for ecology using the programming language R; Step-by-step instructions for fitting models to messy, real-world data; Balanced view of different statistical approaches; Wide coverage of techniques--from simple (distribution fitting) to complex (state-space modeling); Techniques for data manipulation and graphical display; Companion Web site with data and R code for all examples
The number of elephant dung-piles lying on the forest floor is a function of the number of elephants present and the rainfall in the 2 preceding months. We present the results of a stochastic model that describes this relationship and we show how it can be used to estimate elephant numbers. The data from a survey in Sapo NP (Liberia) in 1989 are used as an example. The dung-pile density was estimated at 152 km−2 with confidence interval from 72 to 322, and the number of elephants was estimated to be 313 with confidence interval from 172 to 617.RésuméLe nombre de tas de crottes d'éléphants sur le sol forestier dépend du nombre d'éléphants présents et des chutes de pluies au cours des deux mois précédents. Nous présentons les résultats d'un modèle stochastique qui décrit cette relation et nous montrons comment on peut s'en servir pour estimer le nombre d'éléphants. Les données provenant d'une étude réalisée au PN de Sapo, au Liberia, en 1989, servent d'exemple. La densité des crottes a été estimée à 152 /km2 avec un intervalle de confiance compris entre 72 et 332, et on a estimé le nombre d'éléphants à 313, avec un intervalle de confiance compris entre 172 et 617.
Decaying dung-piles were observed at three sites in the lowland forests of southern Ghana. Time to disappearance was inversely related to rainfall in the month of deposition. The monthly survival of each age-class decreased with age and was inversely proportional to rainfall in the month of deposition. A simulation revealed that if elephant numbers and defaecation rates are constant, then dung density in a given month will be governed by rainfall in the two preceding months. Changes in annual rainfall and its monthly distribution in southern Ghana mean that dung-pile densities will vary from one month to the next, and between the same months in different years, even if elephant numbers are constant. Thus dung counters must take rainfall into account. A new method of censusing elephants in Ghana is presented, and suggestions are made for improving elephant counts in central African forests.
A sample of 1282 fresh elephant dung piles was monitored regularly in rain forest in the Lopé Reserve, Gabon, over a two-year period, and the time taken to reach Stage E of Barnes & Jensen (1987) was recorded. Statistically significant differences were found in mean duration of dung piles in different months. There were negative correlations between mean dung duration and both rainfall in the previous three months and mean humidity between 1300 h and 1500 h. However, the most important factor affecting dung duration was found to be fruit content of the diet in any given month.
On a contrôlé régulièrement un échantillonnage de 1282 excréments frais d'éléphants dans la forêt humide de la Réserve de Lope, au Gabon, pendant deux ans, et on a noté le temps nécessaire pour atteindre le stade E de Barnes & Jensen (1987). On a trouvé des différences statistiquement significatives de la durée moyenne au cours des différents mois. II y avait une corrélation négative entre la durée moyenne des excréments, et les chutes de pluie des trois mois précédents et le taux moyen d'humidité entre 13h et 15h. Cependant, on a trouvé que le facteur influencant le plus la durée des excréments était le contenu en fruits du régime alimentaire au cours des mois.
This paper proposes, focusing on random forests, the increasingly used statistical method for classification and regression problems introduced by Leo Breiman in 2001, to investigate two classical issues of variable selection. The first one is to find important variables for interpretation and the second one is more restrictive and try to design a good parsimonious prediction model. The main contribution is twofold: to provide some experimental insights about the behavior of the variable importance index based on random forests and to propose a strategy involving a ranking of explanatory variables using the random forests score of importance and a stepwise ascending variable introduction strategy.
- J S Makak
- B Mertens
Makak JS, Mertens B. (2009) Atlas Forestier Interactif du Gabon. (Washington, DC: World Resources
Institute).
Model Selection and Multimodel Inference: A Practical Informationtheoretic Approach
- K P Burham
- D R Anderson
Burham KP, Anderson DR. (2003) Model Selection and Multimodel Inference: A Practical Informationtheoretic Approach (Second Edition). (New York, NY: Springer).
Factors affecting the duration of elephant dung piles in rain forest in the Lopé Reserve Hunting alters vertebrate community composition and reduces diversity along a defaunation gradient from rural villages in Gabon
- Lj White
- Se Koerner
- Jr Poulsen
- E Blanchard
- J Okouyi
- Cj Clark
White LJ. Factors affecting the duration of elephant dung piles in rain forest in the Lopé Reserve, Gabon.
African Journal of Ecology 33, 142-150.
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Koerner SE, Poulsen JR, Blanchard E, Okouyi J, Clark CJ. Hunting alters vertebrate community
composition and reduces diversity along a defaunation gradient from rural villages in Gabon. Journal of
Applied Ecology 2016.
[S8]
Variable selection using random forests Selecting pseudo-absences for species distribution models: how, where and how many?
- R Genuer
- Jm Poggi
- C Tuleau-Malot
- M Massin
- F Jiguet
- Ch Albert
- W Thuiller
[S17]
Genuer R, Poggi JM, Tuleau-Malot C. (2010) Variable selection using random forests. Pattern
Recognition Letters 210, 2225-2236.
[S18]
Barbet-Massin M, Jiguet F, Albert CH, Thuiller W. (2012) Selecting pseudo-absences for species
distribution models: how, where and how many? Methods Ecol Evol 3, 327-38.
[S19]