African Conservation Center

Nairobi, Kenya

African Conservation Center

Nairobi, Kenya
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Ahlering M.A.,University of Missouri | Ahlering M.A.,Smithsonian Conservation Biology Institute | Ahlering M.A.,African Conservation Center | Eggert L.S.,University of Missouri | And 8 more authors.
PLoS ONE | Year: 2012

We investigated the genetic metapopulation structure of elephants across the trans Rift Valley region of Kenya and Tanzania, one of the remaining strongholds for savannah elephants (Loxodonata africana) in East Africa, using microsatellite and mitochondrial DNA (mtDNA) markers. We then examined this population structure to determine the source population for a recent colonization event of savannah elephants on community-owned land within the trans rift valley region. Four of the five sampled populations showed significant genetic differentiation (p<0.05) as measured with both mtDNA haplotypes and microsatellites. Only the samples from the adjacent Maasai Mara and Serengeti ecosystems showed no significant differentiation. A phylogenetic neighbour-joining tree constructed from mtDNA haplotypes detected four clades. Clade four corresponds to the F clade of previous mtDNA studies that reported to have originated in forest elephants (Loxodonta cyclotis) but to also be present in some savannah elephant populations. The split between clade four and the other three clades corresponded strongly to the geographic distribution of mtDNA haplotypes across the rift valley in the study area. Clade four was the dominant clade detected on the west side of the rift valley with rare occurrences on the east side. Finally, the strong patterns of population differentiation clearly indicated that the recent colonists to the community-owned land in Kenya came from the west side of the rift valley. Our results indicate strong female philopatry within the isolated populations of the trans rift valley region, with gene flow primarily mediated via male movements. The recent colonization event from Maasai Mara or Serengeti suggests there is hope for maintaining connectivity and population viability outside formal protected areas in the region.


Mose V.N.,African Conservation Center | Mose V.N.,University Pierre and Marie Curie | Nguyen-Huu T.,UMI 209 | Nguyen-Huu T.,University Pierre and Marie Curie | And 3 more authors.
Ecological Complexity | Year: 2012

The recent expansion of human activities such as agriculture has continuously threatened to block wildlife migration corridors that connect Amboseli National Park (Kenya) to surrounding ecosystems. We study the impact of blocked corridors on herbivore populations using a spatial mathematical model that describes the movements and population dynamics of selected species (zebra, wildebeest and Grant's gazelle) based on resource availability. Aggregation methods are used to reduce the complexity of the model which uses actual parameters calibrated from long term data collected in the area for over three decades. The model suggests the need to maintain these connections to sustain species diversity. Our results show that blocked migration corridors lead to competitive exclusion where only one species survives. However, a possible mechanism of maintenance of biodiversity in the area could be due to an exchange of animals between the park and surrounding ecosystems, when the oscillations of species densities in the ecosystems are out of phase compared to each other and to those within the park. © 2012 Elsevier B.V.


Ahlering M.A.,University of Missouri | Ahlering M.A.,Smithsonian Conservation Biology Institute | Ahlering M.A.,African Conservation Center | Maldonado J.E.,Smithsonian Conservation Biology Institute | And 5 more authors.
Conservation Biology | Year: 2013

Biodiversity conservation strategies are increasingly focused on regions outside national protected areas, where animals face numerous anthropogenic threats and must coexist with human settlements, livestock, and agriculture. The effects of these potential threats are not always clear, but they could have profound implications for population viability. We used savannah elephants (Loxodonta africana) as a case study to assess the physiological stress associated with living in a human-livestock-dominated landscape. We collected samples over two 3-month periods in 2007 and 2008. We used fecal DNA to identify 96 individual elephants in a community conservation area (CCA) and measured fecal glucocorticoid metabolite (FGM) concentrations as a proxy for stress. The CCA is community Maasai land managed for livestock and wildlife. We compared the FGM concentrations from the CCA to FGM concentrations of 40 elephants in Amboseli National Park and 32 elephants in the Maasai Mara National Reserve, where human settlements and intense livestock grazing were absent. In the CCA, we found no significant individual differences in FGM concentrations among the elephants in 2007 (p = 0.312) or 2008 (p = 0.412) and no difference between years (p = 0.616). The elephants in the CCA had similar FGM concentrations to the Maasai Mara population, but Amboseli elephants had significantly lower FGM concentrations than those in either Maasai Mara or the CCA (Tukey pairwise test, p < 0.001), due primarily to females excreting significantly lower FGM relative to males (p = 0.025). In the CCA, there was no relation among female group size, average pairwise group relatedness, and average group FGM concentration. We found no clear evidence of chronic stress in elephants living on CCA communal land, which is encouraging for conservation strategies promoting the protection of animals living outside protected areas. © 2013 Society for Conservation Biology No claim to original US government works.


Ahlering M.A.,University of Missouri | Millspaugh J.J.,University of Missouri | Woods R.J.,University of Missouri | Western D.,African Conservation Center | Eggert L.S.,University of Missouri
Animal Conservation | Year: 2011

Crop raiding is one of the most common forms of human-elephant conflict. Deterring elephants from raiding crops requires an understanding of the factors influencing the behavior of the individuals involved. We collected fecal samples from five group ranches in southern Kenya where crop-raiding incidents had occurred (n=10) and two protected areas, Amboseli National Park (n=24) and Maasai Mara National Reserve (n=20). We used molecular sexing to sex the individuals and radioimmunoassay kits to determine the level of glucocorticoid metabolites (i.e. stress hormones) in their dung. All crop-raiding individuals were male and had a significantly elevated concentration of glucocorticoid metabolites as compared with the Amboseli elephants (W=12, P=0.0005). We detected no significant difference between Maasai Mara elephants and either Amboseli or the crop-raiding elephants when just males were compared. Our results suggest that crop raiding may be related to stress in elephants. © 2010 The Authors. Animal Conservation © 2010 The Zoological Society of London.


Ahlering M.A.,University of Missouri | Ahlering M.A.,Smithsonian Conservation Biology Institute | Ahlering M.A.,African Conservation Center | Maldonado J.E.,Smithsonian Conservation Biology Institute | And 5 more authors.
Diversity and Distributions | Year: 2012

Aim Dispersal is a critical component of animal ecology that is poorly understood for most species. In particular, savanna elephants (Loxodonta africana) have been studied for decades in national parks across Africa, but little is known about their dispersal into new or unused habitats or their population dynamics in human-dominated landscapes. We capitalized on a natural dispersal event of savanna elephants recolonizing communal land in southern Kenya to document their demographic characteristics and genetic relationships. Location Rift Valley province of Kenya. Methods We collected faecal samples and used genetic methods to identify individuals, estimate the sex ratio and evaluate the patterns of relatedness within the female groups and male aggregations. We also measured dung bolus circumference to assign age classes to individuals and estimate the age structure. Results We identified 112 individuals with a sex ratio not different from one (1.32:1.00). The age structure was skewed towards younger elephants (71%), suggesting the potential for rapid growth from reproduction. We detected significantly higher kinship levels within female groups (R=0.124±0.023), suggesting that family groups colonized the site, but found little support for higher-order genetic relationships among female groups. Males detected together were unrelated (R=0.003±0.030). Main conclusions Our results suggest that highly social mammals, such as savanna elephants, disperse into unoccupied habitat as family groups and that a young demographic structure and a large number of males might be expected in establishing populations. These findings highlight the potential value of indirect, non-invasive methods for assessing elephant herd and demographic characteristics when direct observations are difficult. © 2012 Blackwell Publishing Ltd.


Dunne T.,University of California at Santa Barbara | Western D.,African Conservation Center | Dietrich W.E.,University of California at Berkeley
Journal of Arid Environments | Year: 2011

Cattle trampling without forage consumption at stocking densities of 0.03-1.4 cows ha -1 was simulated on two dry-season rangelands in Kenya. Experiments under artificial rainfall documented the response of plant cover and production, infiltration, and erosion on a Luvisol and a Vertisol. Trampling reduced plant cover, biomass, and, at the highest rate, regeneration in the ensuing wet season. Infiltration was reduced on the Vertisol but not the Luvisol, although increases in runoff due to trampling were slight. Trampling increased soil loss partly by reducing vegetation cover but mainly by disrupting surface layers of sand on the Luvisol and of clay aggregates on the Vertisol. Soil loss normalized by runoff and rainfall energy declined in a sequence of erosive rainstorms as the sandy surface layer became re-established, but before vegetation recovered. Establishment of a sandy armor layer during runoff events and its disruption by dry-season trampling thus strongly affect soil-loss rates. Trampling limits plant recovery in the ensuing wet season only at intensities typical of settlement and watering centers. The experimental results, generalized with a spatial model of stock density, can be used to estimate the contribution of trampling to forage production and erosion as herding patterns change in response to sedenterization and water development. © 2010 Elsevier Ltd.


Mose V.N.,African Conservation Center | Western D.,African Conservation Center
Ecological Informatics | Year: 2015

We present an assessment of seasonal movements and species distributions in the Amboseli ecosystem, southern Kenya, using spatial cluster analysis for large herbivore populations over the period 1970 to 2010. Six large mammal species were grouped into zones of most similar use based on a spatial hierarchical cluster analysis. The herbivores clustered into metabolic biomass size classes, suggesting variability in migration and habitat utilization patterns at different scales. The analysis shows a steady loss of spatial spread and heterogeneity among six indicator species over the decades. The findings point to the spread of farming, loss of habitat, land subdivision, sedentarization and ivory poaching as key factors causing compression of species in and around Amboseli National Park. The national park and environs is the only cluster showing no loss of species heterogeneity. The analysis highlights large herbivores as more vulnerable to displacement and compression than small species. The hierarchical cluster analysis shows the use of spatial tools in detecting patterns of change across an ecosystem and identifying important areas for land conservation and restoration to sustain species migration and species diversity. © 2015 Elsevier B.V.


Groom R.,University of Bristol | Groom R.,African Conservation Center | Harris S.,University of Bristol
African Journal of Ecology | Year: 2010

Understanding the spatial dynamics of landscape use by free-ranging herbivores is integral for successful ecosystem management. We used binary logistic regression analyses to determine the relative importance of biotic, abiotic and human factors in influencing the distribution (presence/absence) of wild grazers on two Maasai ranches in Kenya's Amboseli-Tsavo ecosystem. Both ranches had low grass biomass and suffered from regular droughts. We found that grazers consistently located themselves where grass biomass was highest, usually irrespective of grass quality, suggesting that forage quantity may be the limiting factor where grass biomass is generally low. The availability of surface water had no significant effect on the likelihood of grazers being present, even in the dry season. © 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd.


Western D.,African Conservation Center | Mose V.N.,African Conservation Center | Worden J.,African Conservation Center | Maitumo D.,African Conservation Center
PLoS ONE | Year: 2015

We monitored pasture biomass on 20 permanent plots over 35 years to gauge the reliability of rainfall and NDVI as proxy measures of forage shortfalls in a savannah ecosystem. Both proxies are reliable indicators of pasture biomass at the onset of dry periods but fail to predict shortfalls in prolonged dry spells. In contrast, grazing pressure predicts pasture deficits with a high degree of accuracy. Large herbivores play a primary role in determining the severity of pasture deficits and variation across habitats. Grazing pressure also explains oscillations in plant biomass unrelated to rainfall. Plant biomass has declined steadily and biomass per unit of rainfall has fallen by a third, corresponding to a doubling in grazing intensity over the study period. The rising probability of forage deficits fits local pastoral perceptions of an increasing frequency of extreme shortfalls. The decline in forage is linked to sedentarization, range loss and herbivore compression into drought refuges, rather than climate change. The results show that the decline in rangeland productivity and increasing frequency of pasture shortfalls can be ameliorated by better husbandry practices and reinforces the need for ground monitoring to complement remote sensing in forecasting pasture shortfalls. Copyright: © 2015 Western et al.


We monitored pasture biomass on 20 permanent plots over 35 years to gauge the reliability of rainfall and NDVI as proxy measures of forage shortfalls in a savannah ecosystem. Both proxies are reliable indicators of pasture biomass at the onset of dry periods but fail to predict shortfalls in prolonged dry spells. In contrast, grazing pressure predicts pasture deficits with a high degree of accuracy. Large herbivores play a primary role in determining the severity of pasture deficits and variation across habitats. Grazing pressure also explains oscillations in plant biomass unrelated to rainfall. Plant biomass has declined steadily and biomass per unit of rainfall has fallen by a third, corresponding to a doubling in grazing intensity over the study period. The rising probability of forage deficits fits local pastoral perceptions of an increasing frequency of extreme shortfalls. The decline in forage is linked to sedentarization, range loss and herbivore compression into drought refuges, rather than climate change. The results show that the decline in rangeland productivity and increasing frequency of pasture shortfalls can be ameliorated by better husbandry practices and reinforces the need for ground monitoring to complement remote sensing in forecasting pasture shortfalls.

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