Browsing by Author "Shombe, H. N."
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Item Activity patterns and fine-scale resource partitioning in the gregarious Kihansi spray toad Nectophrynoides asperginis in captivity(Wiley & Sons, 2014-08-01) Rija, A. A.; Goboro, E. M.; Mwamende, K. A.; Saidi, A.; Kohi, E. M.; Shombe, H. N.Understanding the behavior of species threatened with extinction is important for conservation planning and for solving problems facing species in captivity and the wild. We examined diurnal activity budgets and habitat use of the extinct in the wild Kihansi spray toad to provide insights into ongoing conservation initiatives for this species. Observations on eight target behaviors were made each morning and evening for 14 days, in two subpopulations at Kihansi and University of Dar es Salaam captive breeding centers. There were significantly more bouts of resting than calling, amplexing, hunting, walking, climbing, or feeding. There was no difference in mean time spent in each activity between the two subpopulations. The use of habitat was variable between age classes, subpopulations and sampling time. Young toads spent significantly more time resting at the top of vegetation and on walls while adults restedItem The aftermath of environmental disturbance on the critically endangered Coffea kihansiensis in the Southern Udzungwa Mountains, Tanzania(Sagepub.com, 2011-01-01) Rija, A. A.; Shombe, H. N.; Mwamende, K. A.The endemic Coffea kihansiensis was monitored in the Kihansi gorge over a three year period following diversion of the Kihansi River underground for hydropower production and its associated catastrophic effect on the gorge biota. We assessed the growth status of the coffee population by measuring, along an altitudinal gradient, the height and diameter of 450 randomly selected coffee stems in 18 sampling plots covering ca 1800 m2. We also collected microclimatic data to compare with that collected prior to river diversion. Coffee infestation by parasites was examined by recording the number of stems with signs of infestation. There was no significant change in size of Coffea kihansiensis during the study period. However, the size for immature plants differed between the two sites; LWF and UCF. Parasite infestation differed between reproductive age classes and was greater at lower elevation (800 – 850 m a.s.l …Item Composition and Functional Diversity in Bird Communities in a Protected Humid Coastal Savanna(Hindawi Publishing Corperation, 2015-04) Rija, A. A.; Mgelwa, A. S.; Modest, R. B.; Shombe, H. N.Our current understanding of the vertebrate communities of a newly gazetted Tanzanian coastal national park is limited and strongly taxonomically biased towards large mammals. We conducted bird assessments in three sites in Saadani National Park using species lists to analyze some parameters to inform biodiversity conservation in the area. We recorded 3112 individuals in 268 species falling in 66 families, including 2 endangered, 2 vulnerable, and 6 near threatened species. Both species richness and species diversity varied between sites. Species relative abundances were not different between the sites although some functional groups, especially granivores, were more abundant than others. Bird assemblages included 21 forest specialists (FF-species), 35 forest generalists (F-species), and 68 forest visitors (f-species) overlapping among bushland, wooded grassland, grassland, and thickets suggesting presence of important microhabitats for the forest-associated species in this ecosystem. Bird species richness in a feeding guild also showed marked overlap between habitats suggesting availability of rich food resources for the birds. This paper highlights the importance of maintaining a structurally heterogeneous landscape to sustain diverse bird communities in the area.Item Fire history and management as determinant of patch selection by foraging large mammal herbivores in western Serengeti, Tanzania(Taylor & Francis, 2011-09-30) Rija, A. A.; Shombe, H. N.Although the use of fire as a management tool has increased during the past decades in East African savannas, there is insufficient knowledge about herbivores' utilization of areas with different fire history. We therefore examined large mammal herbivores' preference for patches that differed in fire history to test whether herbivores would non-randomly select patches according to availability. Our study area was the East African Serengeti ecosystem. Animals were recorded along transects at monthly intervals from May 2001 to April 2006, and data on the burnt and non-burnt areas along transects were extracted from existing fire maps. The prediction was tested using chi-square goodness-of-fit test, and selection ratio as a preference index for patch types. Our results show that African buffalo persistently occurred in non-burnt patches, whereas browsers (Giraffe and Kirk's dik-dik) and mixed feeders (Grant's gazelle …Item Notes on Feeding Habits of Spider Nephila sp in an Acacia woodland stand, Kenya(biological research, 2012-10-06) Rija, A. A.; Mwamende, K. A.; Shombe, H. N.AIM: To investigate the feeding habits of the spider Nephila sp and document its behavioural and ecological aspects in its natural environment. METHODS: The study was carried out in Naivasha, Kenya within the Elsamere Field Study Centre (EFSC) compound located on the southern waterfront of Lake Naivasha. We used field surveys of insects and food selectivity model to record the dietary spectrum of the spider as well as examined spider selectivity behaviour for various prey. Also, field feeding experiments were used to test whether Nephila, in its natural environment, catches trapped prey according to taxon and weight and whether prey distance from the spider determines capture in the web. RESULTS: The spider's dietary items constituted five Orders of insects, with the predator showing highest selectivity for Hymenoptera, Diptera and Coleoptera. Prey captured by the webs were significantly fewer than those available to the spider. On the average however, 1.4 insects per web spider per day were available as food for the spiders in the area, perhaps accounting for the localized and densely observed spiders. Also, distance had greatest influence on prey capture by the spider while prey weight and taxon were less important factors. These factors may have played important regulatory function in optimizing spider’s foraging success in the web. CONCLUSION: This study provides insights into understanding the behavioral and ecological aspects of the spider in the natural environment. More research done under indoor controlled environment could reveal more insights into the behavioural repertoire of this species.Item Population density estimates of some species of wild ungulates in Simanjiro plains, northern Tanzania(Wiley Online Library, 2011-02-09) Rija, A. A.; Shombe, H. N.noneItem Spatial metrics effect of forest fragmentation on forest bird abundance and site occupancy probability: the influence of patch size and isolation(Taylor & Francis, 2016-05-20) Robert, M. B.; Shombe, H. N.; Rija, A. A.The persistence of species taxa within fragmented habitats is dependent on the source–sink metapopulation processes, and forest patch size and isolation are key factors. Unveiling species–patch area and/or species–patch isolation relationships may help provide crucial information for species and landscape management. In this study, relationship between forest patch size and isolation with abundance and occupancy probability of forest-dependent birds was investigated. This study was based within a coastal landscape that faces deleterious human activities such as clearing for agriculture. The study aimed to answer the question of whether the size and extent of isolation of forest patches influence abundance and/or occupancy probability of forest-specialist and generalist birds. Two bird species, namely Tiny Greenbul Phyllastrephus debilis subsp. rabai and Yellow-bellied Greenbul Chlorocichla flaviventris …Item Species Richness and Diversity Reveal that Human-Modified Environments are not Wastelands(African Journals Online, 2014-08) Rija, A. A.; Kimario, A.; Shombe, H. N.Urbanization is often associated with the loss of habitats for many species but the pattern of invertebrate abundance in increasingly human-dominated urban areas is less well documented particularly for the expanding urban Africa. This study investigated the composition and community structure of spiders in relation to human activities at the foot of the Uluguru Mountains in Morogoro city, Tanzania. Three different sampling methods: pitfall trapping, sweep netting and active searching were used to collect spiders in the study area and to allow comparison between structurally different habitat sites. Spider abundance differed significantlyItem Urban sprawl and species movement may decimate natural plant diversity in an Afro-tropical city(Springer Netherlands, 2014-04-01) Rija, A. A.; Said, A.; Shombe, H. N.; Mwamende, K. A.; Madoffe, S. S.Although urban sprawl is increasingly becoming a worldwide problem, the effects associated with urbanization on local biodiversity particularly in the developing countries, is still poorly understood. We investigated plant species richness along urban–rural gradients in an Afro-tropical metropolitan Morogoro city in Tanzania, and examined patterns of species movement by humans within and outside the city and its potential impact on habitat homogenization of urban ecosystems. Biodiversity information was assessed in 120 sample plots (25 × 25 m) distributed in core urban, sub-urban and peri-urban (rural) zones, while patterns of plant resource use and species movement were surveyed from 120 households in the study area. We found the highest tree species richness in the urban core (82.6 ± 1.4 species) whereas tree density decreased from peri-urban (465.60 ± 152.03 tree/ha) to urban core (244.00 ± …