Browsing by Author "Ngalason, Wilirk"

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    Ecology and altitudinal distribution of herpetofauna on mount Kilimanjaro, Tanzania
    (University of Dar es Salaam, 2017) Ngalason, Wilirk
    A study on the diversity, habitat use, activity and reproduction of herpetofaunal species with respect to altitude and climatic conditions was conducted on Mt. Kilimanjaro between 2011 and 2012. Standard methods for the study of herpetofaunal species were used. The surveys were conducted along an altitudinal gradient from 1500 m a.s.l. and above during both the dry and the rainy seasons. Twenty-four herpetofaunal species were detected. The diversity of the species declined with an increase in elevation. Sites that were adjacent to each other had greater species similarity than did sites far from one another. Furthermore, species diversity was significantly higher on the leeward than on the windward side, and the number of species varied significantly between different habitat types. Additionally, habitat utilisation by herpetofaunal species varied with elevation. The proportion of diurnal species increased whereas that of nocturnal species decreased with an increase in elevation. Moreover, the proportion of egg-laying (oviparous) species decreased while that of live-bearing (viviparous) species increased with an increase in elevation. The large proportion of species at lower altitudes was seasonal breeders whereas that at higher elevations exhibited extended breeding patterns. The relatively young geological age of the mountain, the decrease in temperature and precipitation with an increase in altitude accompanied by altitudinal zonation of vegetationappeared to be the major determinants of the findings obtained. Future studies are recommended to fill the gaps identified in this study. Additionally, the conservation and management of different habitat types on Mt. Kilimanjaroare recommended for the continued existence of varied herpetofaunalspecies
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    Reproductive biology and ecology of anurans on the lukwangule plateau, Tanzania
    (University of Dar es Salaam, 2005) Ngalason, Wilirk
    The reproductive biology and ecology of anurans on the Lukwangule Plateau was studied between August 2002 and July 2003. Methods that were used included bucket pitfall naps with drift fences, plots, audio-strip surveys and opportunistic surveys. The reproductive condition of females was assessed based on the condition and size of follicles in the ovary and that of males was assessed based on advertisement calls and secondary sex characters. Environmental parameters influencing amphibian activity including temperature and rainfall were recorded. The Lukwangule Plateau is a mosaic of grassland and forest patches. A total of five anuran species were found, including undescribed nectophrynoides sp., N. viviparous Probreviceps uluguruensis, Arthroleptis affinis and strongylopus merumountanus. N. viviparous and P. uluguruensis were found both in grassland and forest. S. merumontanus was found in grasslands and associated wetlands and Nectophrynoides sp. And A. affinis were found only in forest. Movements in P. uluguruensis and S. merumontanus was positively correlated with both rainfall and temperature. Male advertisement calls in the two species were also correlated with temperature and rainfall. Movements in N. viviparous were positively correlated with temperature but not rainfall, and vocalisations were positively correlated with rainfall but not temperature. The three species had different reproductive modes. P. uluguruensis ' had a direct development mode of reproduction and eggs were laid in burrows at the beginning of short rains. The clutch size ranged from 8 to 55 follicles and the follicles attained a maximum diameter of 5 mm. N. viviparous is ovoviviparous; the clutch size ranged from 18 to 79 eggs/embryos and follicles attained a maximum diameter of 2.8 mm. This species gave birth to young toads during the short rains in November through December. Eggs of £ were laid at the edge of shallow water pools and had aquatic larval stage. This species reproduced during the long rains and the short rains. There was a significant correlation between body length and mass in all anuran species and females were significantly larger than males. The diet of the three species was datum)med more by any preference than availability. In this study, recommendations for conserving the unique habitats and amphibians on the Lukwangule Plateau are put forward.