Lake Bogoria, in the Rift Valley of Kenya is an extreme saline lake (conductivity 40-80 mS cm −1 , alkalinity 1500 m equ l −1 ). It is hydrologically more stable than the other, endorheic lakes in Kenya, because it is deepmaximum depth at present just over 10 m in an area of 3000 ha -and so does not have periods when it is dry. It is ecologically simple, with only one species dominating the phytoplankton -the cyanobacterium 'spirulina', Arthrospira fusiformis. Its biomass and productivity were very high -biomass between 38 and 365 µg l −1 chlorophyll 'a' and 3.4-21 × 10 3 coils ml −1 and net production between 0.24 and 1 gm C m 3 h, the latter in a narrow zone of less than a metre. There were no macro-zooplankton in the plankton and the only grazer of A. fusiformis was the lesser flamingo, Phoeniconaias minor, which occurred irregularly in very high concentrations (in excess of 1 × 10 6 ). Detritivory in the benthos was effected by a single chironomid species, Paratendipes sp., at a maximum density of 4 × 10 4 m −2 . The mean daily emergence of adult chironomids was estimated to be 1 × 10 3 m −2 , the maximum 3. There was no littoral plant community within the lake but 44 dicotyledonous and 31 monocotyledonous plant species in the drawn-down zone and adjacent to it. A diverse draw-down terrestrial invertebrate fauna, only superficially described here, processed the flamingo feathers and carcasses, with other detritus such as chironomid pupal exuviae and decaying A. fusiformis scum. About 50 bird species depended upon the chironomids, either as they emerged through the water column as flying adults or later on the shoreline as floating pupal exuvia and dead adults. The lake has high conservation value because of three bird species in particular -lesser flamingo, Cape teal and black-necked grebe. The former provides real economic value in a region otherwise impoverished, because of the spectacle of tens of thousands of flamingos set against the landscape of hot springs and fumaroles at the lake edge, which draws 15 000 visitors per annum. P. minor has experienced three periods during the past ten years when major mortalities have occurred, the last of which killed 700 birds day −1 . This could have involved as many as 200 000 birds (about 1/5th of the maximum population at this lake) if mortality was at a constant rate for the nine months it was observed. Causes of mortality have been suggested as avian tuberculosis, poisoning from cyanobacterial toxins or from heavy metal contamination at Lake Nakuru, but it is still not yet clear what contribution each makes to the problem.

Lake Bogoria, in the Rift Valley of Kenya is an extreme saline lake (conductivity 40-80 mS cm −1 , alkalinity 1500 m equ l −1 ). It is hydrologically more stable than the other, endorheic lakes in Kenya, because it is deepmaximum depth at present just over 10 m in an area of 3000 ha -and so does not have periods when it is dry. It is ecologically simple, with only one species dominating the phytoplankton -the cyanobacterium 'spirulina', Arthrospira fusiformis. Its biomass and productivity were very high -biomass between 38 and 365 µg l −1 chlorophyll 'a' and 3.4-21 × 10 3 coils ml −1 and net production between 0.24 and 1 gm C m 3 h, the latter in a narrow zone of less than a metre. There were no macro-zooplankton in the plankton and the only grazer of A. fusiformis was the lesser flamingo, Phoeniconaias minor, which occurred irregularly in very high concentrations (in excess of 1 × 10 6 ). Detritivory in the benthos was effected by a single chironomid species, Paratendipes sp., at a maximum density of 4 × 10 4 m −2 . The mean daily emergence of adult chironomids was estimated to be 1 × 10 3 m −2 , the maximum 3. There was no littoral plant community within the lake but 44 dicotyledonous and 31 monocotyledonous plant species in the drawn-down zone and adjacent to it. A diverse draw-down terrestrial invertebrate fauna, only superficially described here, processed the flamingo feathers and carcasses, with other detritus such as chironomid pupal exuviae and decaying A. fusiformis scum. About 50 bird species depended upon the chironomids, either as they emerged through the water column as flying adults or later on the shoreline as floating pupal exuvia and dead adults. The lake has high conservation value because of three bird species in particular -lesser flamingo, Cape teal and black-necked grebe. The former provides real economic value in a region otherwise impoverished, because of the spectacle of tens of thousands of flamingos set against the landscape of hot springs and fumaroles at the lake edge, which draws 15 000 visitors per annum. P. minor has experienced three periods during the past ten years when major mortalities have occurred, the last of which killed 700 birds day −1 . This could have involved as many as 200 000 birds (about 1/5th of the maximum population at this lake) if mortality was at a constant rate for the nine months it was observed. Causes of mortality have been suggested as avian tuberculosis, poisoning from cyanobacterial toxins or from heavy metal contamination at Lake Nakuru, but it is still not yet clear what contribution each makes to the problem.

Kakamega forest is Kenya's only rainforest and is distinguishably rich in biodiversity but threatened by agricultural encroachment and other forms of human activity. It is also one of Kenya's Important Bird Areas and a significant source of natural products to neighboring rural communities, such as medicinal plants, food, wood and other fibers. By using structured questionnaires for direct interviews, local indigenous knowledge was tapped through involvement of a focal group of elderly key informants in three blocks of the forest. Forty key species of medicinal plants used by local people were identified and recorded. Fifty-five percent of these were shrubs, thirty-two percent trees, seven-and-a-half percent lower plants such as herbs or forbs while five percent were climbers. About seventy percent of the medicinal plants occurred inside the forest itself and thirty percent around the edge and the immediate surroundings outside the forest. Thirty-eight (95%) of the plants were indigenous to Kenya and two (5%) exotic. Such extensive indigenous knowledge of the medicinal uses of the plants, including their distribution trends in the forest, may be tapped for decision support in rural health service planning, policy formulation for conserving the forest, tracking and mitigation of climate change impacts.

No abstract

The timing and location of reproduction are fundamental elements of reproductive success for all organisms. Understanding why animals choose to reproduce at particular times and in particular places is also important for our understanding of other aspects of organismal ecology, such as their habitat requirements, movement strategies, and biogeography. Although breeding patterns in waterfowl are relatively well documented, most studies are from northern temperate regions and the influences of location and time of year on breeding in Afrotropical ducks (Anatidae) are poorly understood. We outline six alternative (but not mutually exclusive) hypotheses that might explain where and when Afrotropical ducks choose to breed. To explore these hypotheses, we assembled and analyzed a new database of c. 22,000 breeding records for 16 Afrotropical ducks and one introduced Palearctic species (the Mallard Anas platyrhynchos). The full database is available on line as an appendix to this article. We identified five distinct breeding strategies as well as two outliers. Peak breeding for 9 of 16 indigenous duck species occurs during the dry season. We found no evidence for spatial synchrony or spatial autocorrelation in breeding, suggesting a high level of flexibility in waterfowl responses to prevailing conditions in any given year. More intensive analyses of alternative hypotheses are needed, but our initial analysis suggests that the timing of breeding for the majority of Afrotropical ducks is driven by a combination of resource availability and predation risk.

Since the late 1950's, the Malaysian human population has nearly quadrupled, increasing pressure on natural resource exploitation to meet domestic needs and to earn foreign exchange from exports. Global demand for Malaysian palm oil in particular had steeply increased since the mid-1970s and by 2013, the commodity was the leading foreign exchange earner. To fulfill and sustain this demand, the country's economy has steadily shifted bias towards production and associated value addition of palm oil products for export. However, as a consequence, many of Malaysia's natural tropical forests have been converted to palm oil farming resulting in loss of approximately 10,000 km² of forest cover over the past twenty-five years, and biodiversity has been displaced or lost. To provide a deeper insight into the interplay amongst key interrelated environmental and socio-economic variables, and a forecast of possible future balance, we used a systems dynamism modeling tool, STELLA R (structural thinking, experiential learning laboratory with animation), to simulate and project how Malaysia could achieve a medium-term sustainable balance or optimization between palm oil production and forest conservation without compromising on human social welfare. The model consisted of four main modules (environmental, economic, social development and human welfare) each with component parameters, and interconnected by input and output loops. Model calibrations, testing and pre-runs involved existing official 30-year time-series datasets. Subsequently, four scenarios: Environmental conservation; Economic growth under increased global palm oil demand; Economy decline under decreased palm oil demand; and Control condition with little or no change, were selected for simulated projections of future possibilities. Simulation results showed that scenarios and variable interactions that reduce environmental N. E. Otieno et al. 56damage would offer the best chance for optimizing the palm oil economy while also minimizing forest loss and promoting citizen social welfare.

The Arabuko-Sokoke forest is the largest relic of a formerly larger contiguous East African coastal forest. It forms part of the Eastern Arc Forest system which is a global biodiversity hotspot with considerable species endemism. As one of the most important bird habitats in Africa, it hosts nine globally-threatened and four regionally threatened species. Despite such conservation significance, the forest is undergoing rapid modification and habitat loss mainly from anthropogenic pressures, with negative impacts on sensitive species such as the Sokoke Pipit (Anthus sokokensis). This study examined impacts of change in habitat quality on the species’ population and spatial occurrence within three blocks of Brachystegia woodland in the forest. Over a three week period, six 1-km transects were used to estimate the species’ population in relation to major habitat quality variables. Sokoke Pipits occurred at an overall mean density of 0.72±0.15 birds/ha with an estimated population of 5,544 in the Brachystegia woodland. Tree logging intensity was the key cause of the degradation of the Sokoke Pipit’s critical habitat, which affected its density (R2 = 0.663, ß = -0.814, p = 0.048). The species also preferred sites covered with deep floor litter (R2 = 0.769, ß = 0.877, p = 0.021) even in areas with low tree canopy height, but showed no clumped distribution (χ2(2, 0.05) = 2.061). Sites with intensive elephant activity, which leads to tree felling and clearing of the understorey, had low Sokoke Pipit densities. We conclude that  although human-driven tree removal is a major driver of degradation of the Sokoke Pipit’s critical habitat, elephant activity may be an important additional factor in this process. Long term conservation strategies for the species will require stricter control of logging but management of the population and dispersal of elephants across the forest, especially in Brachystegia woodland, may also be helpful.

No abstract