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Nairobi, Kenya

Otieno P.O.,Maseno University | Lalah J.O.,Maseno University | Virani M.,Ornithology Section | Jondiko I.O.,Maseno University | Schramm K.-W.,Helmholtz Center for Environmental Research
Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes | Year: 2010

This study was undertaken to determine the concentrations of carbofuran residues in water, soil and plant samples from selected sites in the farmlands in Kenya and to demonstrate the impact of Furadan use on the local environment. Soil, water and plant samples obtained from agricultural farmlands where the technical formulation Furadan has been used extensively showed high environmental contamination with concentrations of carbofuran and its two toxic metabolites 3-hydroxycarbofuran and 3-ketocarbofuran, separately, ranging from 0.010-1.009 mg/kg of dry surface soil, 0.005-0.495 mg/L in water samples from two rivers flowing through the farms and bdl-2.301 mg/L in water samples from ponds and dams located close to the farms. Maize plant samples contained these residues in concentrations ranging from 0.04-1.328 mg/kg of dry plant tissue. The significantly high concentration levels of carbofuran and its metabolites, 3-ketocarbofuran and 3-hydroxycarbofuran, found in various matrices demonstrate that Furadan was used extensively in the two areas and that there was environmental distribution and exposure of residues in water which posed risks when used for domestic purposes or as drinking water for animals in two wildlife conservancies where the dams and ponds are located. Surface soil contamination was also high and posed risks through run-off into the dams and rivers as well as through secondary exposure to small birds and mammals. © Taylor & Francis Group, LLC. Source

Ndang'ang'a P.K.,BirdLife International Africa Partnership Secretariat | Ndang'ang'a P.K.,Jomo Kenyatta University of Agriculture and Technology | Njoroge J.B.M.,Jomo Kenyatta University of Agriculture and Technology | Githiru M.,Ornithology Section
Ostrich | Year: 2013

We examined the effects of vegetation composition and structure on bird species diversity and richness of foraging guilds in the highland agricultural landscape of Nyandarua, Kenya. Bird point counts and vegetation surveys were undertaken during four sampling periods. Linear mixed models were used to examine the effects of vegetation variables on bird species diversity and richness of respective foraging guilds, and logistic generalised linear models used to examine vegetation effects on the presence/absence of the 17 most common bird species. Bird species diversity increased with increasing density of woody plant species and vegetation structural heterogeneity. Two gradients of increasing vegetation structural heterogeneity were most important in influencing bird community composition and had positive effects on species diversity and the presence of most of the species assessed: (1) increasing closed cover due to woody plant density, which also had positive effects on species richness of frugivores and nectarivores, but negative effects on carnivores, and (2) increasing fallow and cultivation versus decreasing grassland/pasture cover, which also had a positive effect on species richness of granivores and omnivores. This study reaffirms the need to maintain a structurally rich agricultural landscape for it to support agrobiodiversity. © 2013 Copyright © NISC (Pty) Ltd. Source

Cox S.C.,University College London | Cox S.C.,Bird Group | Prys-Jones R.P.,Bird Group | Habel J.C.,TU Hamburg - Harburg | And 2 more authors.
Molecular Ecology | Year: 2014

The Eastern Afromontane biodiversity hotspot composed of highly fragmented forested highlands (sky islands) harbours exceptional diversity and endemicity, particularly within birds. To explain their elevated diversity within this region, models founded on niche conservatism have been offered, although detailed phylogeographic studies are limited to a few avian lineages. Here, we focus on the recent songbird genus Zosterops, represented by montane and lowland members, to test the roles of niche conservatism versus niche divergence in the diversification and colonization of East Africa's sky islands. The species-rich white-eyes are a typically homogeneous family with an exceptional colonizing ability, but in contrast to their diversity on oceanic islands, continental diversity is considered depauperate and has been largely neglected. Molecular phylogenetic analysis of ∼140 taxa reveals extensive polyphyly among different montane populations of Z. poliogastrus. These larger endemic birds are shown to be more closely related to taxa with divergent habitat types, altitudinal distributions and dispersal abilities than they are to populations of restricted endemics that occur in neighbouring montane forest fragments. This repeated transition between lowland and highland habitats over time demonstrate that diversification of the focal group is explained by niche divergence. Our results also highlight an underestimation of diversity compared to morphological studies that has implications for their taxonomy and conservation. Molecular dating suggests that the spatially extensive African radiation arose exceptionally rapidly (1-2.5 Ma) during the fluctuating Plio-Pleistocene climate, which may have provided the primary driver for lineage diversification. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd. Source

Callens T.,Ghent University | Galbusera P.,Center for Research and Conservation | Matthysen E.,University of Antwerp | Durand E.Y.,University of California at Berkeley | And 3 more authors.
Molecular Ecology | Year: 2011

Habitat fragmentation can restrict geneflow, reduce neighbourhood effective population size, and increase genetic drift and inbreeding in small, isolated habitat remnants. The extent to which habitat fragmentation leads to population fragmentation, however, differs among landscapes and taxa. Commonly, researchers use information on the current status of a species to predict population effects of habitat fragmentation. Such methods, however, do not convey information on species-specific responses to fragmentation. Here, we compare levels of past population differentiation, estimated from microsatellite genotypes, with contemporary dispersal rates, estimated from multi-strata capture-recapture models, to infer changes in mobility over time in seven sympatric, forest-dependent bird species of a Kenyan cloud forest archipelago. Overall, populations of sedentary species were more strongly differentiated and clustered compared to those of vagile ones, while geographical patterning suggested an important role of landscape structure in shaping genetic variation. However, five of seven species with broadly similar levels of genetic differentiation nevertheless differed substantially in their current dispersal rates. We conclude that post-fragmentation levels of vagility, without reference to past population connectivity, may not be the best predictor of how forest fragmentation affects the life history of forest-dependent species. As effective conservation strategies often hinge on accurate prediction of shifts in ecological and genetic relationships among populations, conservation practices based solely upon current population abundances or movements may, in the long term, prove to be inadequate. © 2011 Blackwell Publishing Ltd. Source

Kendall C.J.,Princeton University | Virani M.Z.,Ornithology Section | Hopcraft J.G.C.,Frankfurt Zoological Society | Bildstein K.L.,Acopian Center for Conservation Learning | Rubenstein D.I.,Princeton University
PLoS ONE | Year: 2014

The ongoing global decline in vulture populations raises major conservation concerns, but little is known about the factors that mediate scavenger habitat use, in particular the importance of abundance of live prey versus prey mortality. We test this using data from the Serengeti-Mara ecosystem in East Africa. The two hypotheses that prey abundance or prey mortality are the main drivers of vulture habitat use provide alternative predictions. If vultures select areas based only on prey abundance, we expect tracked vultures to remain close to herds of migratory wildebeest regardless of season. However, if vultures select areas where mortality rates are greatest then we expect vultures to select the driest regions, where animals are more likely to die of starvation, and to be attracted to migratory wildebeest only during the dry season when wildebeest mortality is greatest. We used data from GSM-GPS transmitters to assess the relationship between three vulture species and migratory wildebeest in the Mara-Serengeti ecosystem. Results indicate that vultures preferentially cluster around migratory herds only during the dry season, when herds experience their highest mortality. Additionally during the wet season, Ruppell's and Lappet-faced vultures select relatively dry areas, based on Normalized Difference Vegetation Index, whereas White-backed vultures preferred wetter areas during the wet season. Differences in habitat use among species may mediate coexistence in this scavenger guild. In general, our results suggest that prey abundance is not the primary driver of avian scavenger habitat use. The apparent reliance of vultures on non-migratory ungulates during the wet season has important conservation implications for vultures in light of on-going declines in non-migratory ungulate species and use of poisons in unprotected areas. © 2014 Kendall et al. Source

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