Roadless wilderness area determines forest elephant movements in the Congo Basin

A dramatic expansion of road building is underway in the Congo Basin fuelled by private enterprise, international aid, and government aspirations. Among the great wilderness areas on earth, the Congo Basin is outstanding for its high biodiversity, particularly mobile megafauna including forest elephants (Loxodonta africana cyclotis). The abundance of many mammal species in the Basin increases with distance from roads due to hunting pressure, but the impacts of road proliferation on the movements of individuals are unknown. We investigated the ranging behaviour of forest elephants in relation to roads and roadless wilderness by fitting GPS telemetry collars onto a sample of 28 forest elephants living in six priority conservation areas. We show that the size of roadless wilderness is a strong determinant of home range size in this species. Though our study sites included the largest wilderness areas in central African forests, none of 4 home range metrics we calculated, including core area, tended toward an asymptote with increasing wilderness size, suggesting that uninhibited ranging in forest elephants no longer exists. Furthermore we show that roads outside protected areas which are not protected from hunting are a formidable barrier to movement while roads inside protected areas are not. Only 1 elephant from our sample crossed an unprotected road. During crossings her mean speed increased 14-fold compared to normal movements. Forest elephants are increasingly confined and constrained by roads across the Congo Basin which is reducing effective habitat availability and isolating populations, significantly threatening long term conservation efforts. If the current road development trajectory continues, forest wildernesses and the forest elephants they contain will collapse

Les <i>Petrocephalus</i> (Pisces, Osteoglossomorpha, Mormyridae) du Gabon, Afrique Centrale, avec la description d’une nouvelle espèce

Dans ce travail, nous étudions la variabilité morphologique ainsi que la forme des décharges électriques organiques (DEO) des Petrocephalus Marcusen, 1854 (Pisces, Osteoglossomorpha, Mormyridae) présents au Gabon (Afrique Centrale). Ceci nous a permis d’y reconnaître quatre espèces : P. simus Sauvage, 1879, P. balayi Sauvage, 1883 (= Mormyrus amblystoma Günther, 1896), P. microphthalmus Pellegrin, 1908 et P. sullivani n. sp. Petrocephalus sullivani n. sp. se distingue des trois autres espèces par la combinaison des caractères suivants : absence de tache noire sous-dorsale ; plus de 18 rayons branchus à la nageoire dorsale ; plus de 14 écailles (rarement 14) entre l’origine de la nageoire anale et la ligne latérale ; la bouche est située en position infère, la distance du museau à la bouche étant comprise en moyenne 3,2 fois dans la longueur de la tête (minimum : 2,7 et maximum : 4,4). Enfin, les DEO ont une durée de 216 ± 29 microsecondes, avec une troisième phase (P3) proéminente. La distribution géographique de chacune des quatre espèces est résumée et une clé d’identification des espèces de Petrocephalus du Gabon est proposée, qui est fondée sur des caractères diagnostiques de la morphologie externe.In this paper, we study variation in the morphology and electric organ discharges (EODs) of Petrocephalus Marcusen, 1854 (Pisces, Osteoglossomorpha, Mormyridae) collected in Gabon, Central Africa. We recognize four valid species: P. simus Sauvage, 1879, P. balayi Sauvage, 1883 (= Mormyrus amblystoma Günther, 1896), P. microphthalmus Pellegrin, 1908, and P. sullivani n. sp. Petrocephalus sullivani n. sp. differs from all others by the following combination of characters: lack of black spot at the base of the dorsal fin; more than 18 branched rays on the dorsal fin; more than 14 scales (rarely 14) between the origin of the anal fin and the lateral line; inferior mouth with the distance from the anterior extremity of the snout to the mouth between 2.7 and 4.4 times in head length (average 3.2); and EOD duration 216 ± 29 microseconds, with prominent third phase (P3). We summarize the geographical distribution of each species and provide a key to species of the genus Petrocephalus from Gabon based on diagnostic characteristics from external morphology.</p

Patterns of microhabitat use among fourteen abundant fishes of the lower Ntem River Basin (Cameroon)

A study of microhabitat use by fourteen abundant fish species was undertaken in the lower Ntem River Basin in Cameroon (Africa). Seventy-one microhabitats including pools, raceways and riffles were studied twice during the 1994 and 1995 dry season. Results obtained by Canonical Correspondence Analysis (CCA) showed a good niche separation along the ordination axes I (λ1 = 0.37) and II (λ2 = 0.20). Microhabitat selection by these species reflects response to several physical factors including width, depth, current velocity and substrate type. However, a substantial part of the variation in species segregation was explained by both instream (% leaves, woods and roots, and aquatic plants) and bankside (% mean canopy closure) cover. A striking pattern encountered during this study was the frequent size-related variation in habitat use displayed by many species. For example, smaller individuals of Brycinus longipinnis, Barbus camptacanthus, Distichodus notospilus, and D. hypostomatus, occurred more often in faster flowing waters than did their larger conspecifics. The association displayed by CCA was high (0.957 and 0.938, respectively for the first and second axis), and Monte Carlo test (99 permutations) revealed that these associations were significantly different from random (p = 0.01). The implications of these results for habitat management are discussed

Catastrophic ape decline in western equatorial Africa

Additional co-authors: Yves Mihindou, Sosthène Ndong Obiang, Ernestine Ntsame Effa, Malcolm P. Starkey, Paul Telfer, Marc Thibault, Caroline E. G. Tutin, David S. Wilkie Output Type: Lette