Browsing by Author "Howell, Kim M."
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Item Kimboza Forest Reserve, Tanzania: An important cold season refugium for altitudinal migrating birds(Wiley, 2016-04) Werema, Chacha; Howell, Kim M.; Ndangalasi, Henry J.Altitudinal migration of birds is defined as movements of individuals from higher to lower altitudes and vice versa due to different causes such as variations in food availability (Chaves-Campos, Arévalo & Araya, 2003; Boyle, 2010), changes in weather (Boyle, Norris & Guglielmo, 2010) or trade-offs between predation and survival (Boyle, 2008). Altitudinal migrations of birds have been reported to exist for most major mountain ranges of the world (Mcguire & Boyle, 2013). In Africa, altitudinal migration of birds has been documented by several authors (e.g. West Africa: Stuart, 1986; south-central Africa: Dowsett-Lemaire, 1989; Southern Africa: Oatley, 1982; Johnson & Maclean, 1994; East Africa: Stuart, 1983; Stuart et al., 1993; Burgess & Mlingwa, 2000; Werema, 2015a). Several studies have discussed the aspect of altitudinal migration of birds in the Eastern Arc Mountains (Stuart, 1983; Stuart et al., 1993; Burgess & Mlingwa, 2000; Werema, 2015a). However, relatively little is known for some areas, particularly in the isolated forest fragments that are found at the lower altitudes. This note presents findings on the effects of season on understorey bird assemblages in Kimboza Forest Reserve, an isolated forest fragment located about 12 km from Uluguru Mountains. The main emphasis is on the aspect of altitudinal migration because no quantitative studies on altitudinal migratory birds covering different seasons are available in this forest reserveItem Reproduction in Brevicipitid Frogs (Amphibia: Anura: Brevicipitidae)—Evidence from Probreviceps M. Macrodactylus(2007) Müller, Hendrik; Loader, Simon P.; Ngalason, Wilirk; Howell, Kim M.; Gower, DavidAn egg clutch of the Tanzanian brevicipitid frog, Probreviceps m. macrodactylus, is described for the first time. The single clutch consists of 32 eggs and 21 infertile, jelly-filled capsules, tightly bound together by a thin, tough outer layer. The infertile capsules are concentrated toward the top of the clutch. The eggs were found in a dry season, and were perhaps likely to hatch at the onset of the short rains. The specific identification is confirmed through analysis of mitochondrial DNA sequence data. Eggs are yolky and large, about 8 mm in diameter (including capsule), suggesting that P. m. macrodactylus has a direct mode of development. The embryos observed were in an early developmental stage and showed the early division of the brain and anlagen of three pairs of visceral arches. Brevicipitid reproduction and development are poorly known, but a review of the existing literature and parsimonious optimization of simple characters onto a phylogenetic framework suggest that direct development is a derived condition characterizing the whole clade.Item Seasonal variation in diversity and abundance of understorey birds in Bunduki Forest Reserve, Tanzania: evaluating the conservation value of a plantation forest(Taylor & Francis, 2015-12) Werema, Chacha; Howell, Kim M.Plantation forests generally support lower bird diversity than natural forests. However, in some instances the plantations have been found to provide suitable habitat for a number of bird species. In the Eastern Arc Mountains, there is limited knowledge how understorey birds, some of which make seasonal altitudinal movements, use plantations. Using mist netting we assessed seasonal use of the plantation forest by the understorey bird community in Bunduki Forest Reserve in the Uluguru Mountains. Species diversity and capture rates were significantly higher during the cold season than during the hot season possibly due to seasonal altitudinal migration by some species. The use of plantations by those species that make seasonal altitudinal movements shows that plantation forests can enhance indigenous biodiversity by enabling connectivity between two or more natural forest patches. Our findings suggest that in a situation where there is no natural forest, an exotic plantation with suitable indigenous understorey cover can help in protection of birds, including endemic and near-endemic species.Item Spatial and Temporal Variations in the Abundance and Diversity of Phytoplankton in Lake Manyara, Tanzania(2015-04) Kihwele, Emilian; Lugomela, Charles; Howell, Kim M.; Nonga, Hezron E.This study evaluated the temporal dynamics of phytoplankton species diversity and abundance in relation to some physico-chemical parameters in Lake Manyara for a period of fourteen consecutive months (between July 2007 and August 2008). The aim was to relate the temporal variability in the physico-chemical parameters of the lake to the abundance and diversity of phytoplankton. Three sampling sites were established in the lake, and data were collected once every month. Electrical conductivity, salinity, water temperature, dissolved oxygen; turbidity, transparency and pH were measured in-situ using a water quality checker Water samples for nutrients and phytoplankton abundance and species composition were analysed at the University of Dar es Salaam. In the laboratory, the concentration for inorganic nutrients were determined using a Shimadzu UV-spectrophotometer. Salinity and pH values in the lake ranged from 0.1 ‰ to 40 ‰ and from 6.23 to 10.67 respectively. However, there were shift in phytoplankton community dominance between Anabaena sp to Arthrospira sp likely due to differences in salinity and pH thresholds requirements. Nitrate, phosphate and ammonium concentrations ranged from 0.5 to 3.2 µg/l, 0.5 to 570 µg/l and 0.5 to 10.5 µg/l respectively while conductivity varied between 8.7 to 84.5 mS/cm. Other cyanobacterial genera, Phormidium, Oscillatoria, Spirulina, Aphanocapsa and Synechoccocus were also common. The results indicated that phytoplankton assemblage was positively correlated with ammonium, phosphate, dissolved oxygen, conductivity and nitrate.Item Temporal Changes in the Lesser Flamingos Population ( Phoenicopterus minor ) in Relation to Phytoplankton Abundance in Lake Manyara, Tanzania(Scientific Research, 2014) Kihwele, Emilian; Lugomela, Charles; Howell, Kim M.A study on seasonal variations in the abundance of Lesser Flamingo (Phoenicopterus minor) in relation to phytoplankton abundance in lake Manyara was conducted for a period of fourteen consecutive months (July 2007 to August 2008). The aim was to relate the temporal variability in the phytoplankton species abundance and diversity of the lake to the population size of the Lesser Flamingo. Lesser Flamingo population numbers were obtained from monthly ground surveys whereby the lake was subdivided into defined counting vantage points. Water samples for phytoplankton species composition and biomass analyses were taken to the University of Dar es Salaam for laboratory analysis. The flamingo population estimates ranged from 9319 in August 2007 to 640,850 in August 2008. The Lesser Flamingo populations showed that temporal fluctuations were related to the changes in the abundance and diversity of phytoplankton species. The occurrence of Arthrospira associated with the increase in the abundance of Lesser Flamingo. It was observed that changes in the Lesser Flamingo numbers were influenced by the changes in the abundance and availability of their preferred food. The results indicated that microalgae assemblage positively correlated with ammonium and nitrate which were also related to the abundance of lesser flamingo. The phytoplankton community was dominated by cyanobacteria particularly Arthrosipira fusiformis likely due to the high lake salinity and pH that limited the growth of other microalgae. Correlation analysis showed strong correlation between the Lesser Flamingo abundance with the concentration of nitrate and ammonium and between the number of Lesser Flamingo and the cyanobacterium Arthrospira.