THE IMPACT OF AWKA URBAN VEGETATION DISTRIBUTION ON BIRD ABUNDANCE, SPECIES RICHNESS AND DIVERSITY

AUTHOR: OBUDULU CHIBUZOR

DEPARTMENT: ZOOLOGY

AFFILIATION: NNAMDI AZIKIWE UNIVERSITY, AWKA

The study of the impact of Awka urban vegetation distribution on bird abundance, species richness and diversity was carried out in Awka, the Anambra state capital, Nigeria. The study was done in the residential area, non residential area, agricultural area, commercial area, and a forest which acted as a reference site. Bird sampling data, vegetation sampling data and weather data were collected during the study using the fixed radius point count method for birds; the l0m by 10m plot for trees sampling and 1m by a 1m sub plot for non tree vegetation species; and weather data using the celsius thermometer for temperature, the digital hygrometer for humidity, the digital anemometer for wind speed and the lux meter for light intensity. 69 bird species belonging to 32 families were observed during the study. Colurnbidae, Lybidae, Cuculidae and Sylvidae with 6, 6, 5, 5 species respectively were the dominant families. The African pied crow (Corvus albus), African black kite (Milvus migrans), and the Northern grey-head sparrow (Passer griseus) were the most widely distributed species with 64.7%, 5 8.8% and. 41.2% respectively. The study showed that urbanization creates habitats different from the natural ones that harbor different types of birds. The Red eye dove (Streptopelia semitorquata). Common bulbul (Pycnonotus barbatus), Barrati warbler (Bradypterus barrati) and Laughing dove (Streptepelia senegalensis) showed affinity for the residential area; the Rock pigeon (Columba livia) and Northern Greyhead sparrow (Passer griseus) for the commercial area; the Blue spotted wood dove (Turtur afer), Yellow rumped Tinker bird (Pogoniulus bilineatus), Yellow billed barbet (Trachyphonus purpuratus), and European bee eater (Merops apiaster) for the palm plantation, and several birds for the forest. The study showed that urbanization had a negative impact on birds and plants reducing their species richness and diversity and affecting their abundance. While the populations of native species were reduced and in certain cases eliminated, the populations of non native species that were able to thrive in modified habitats increased. There was a significant decrease in bird species richness across the sites, from forest to the commercial area. The study also showed a significant increase in bird’s abundance across the sites, from forest to the commercial area. The study showed a significant decrease in floral abundance, richness and diversity; and a significant decrease in tree abundance, richness and diversity from the forest to the commercial area, Floral abundance and floral species richness had little or no impact on the abundance and species richness of birds, while vegetation height (of which trees contribute a significant part), tree species richness and tree abundance had very significant effect on birds species richness. This shows the importance of trees in birds’ conservation and preservation. Birds’ species richness was positively correlated with flora species richness, the regression test was not significant (p>0.05); and negatively correlated with flora abundance the regression test was not significant (p>0.05). Birds’ species richness was also positively correlated tree richness, the regression test was significant (p<0.05); and positively correlated with tree abundance, the regression test was significant p<0.05). Bird species richness was positively correlated with foliage height across the site, the regression test was significant (p<0.05); and positively correlated with tree stand basal area, the regression test was not significant p>0.05). Bird abundance was negatively correlated with flora abundance, the regression test was significant p<0.05); and negatively correlated with flora species richness, the regression test was significant p<0.05). Bird abundance was also positively correlated with tree species richness, the regression test was not significant (p>0.05); and positively correlated with tree abundance, the regression test was not significant (p>0.05) Birds’ abundance was positively correlated with foliage height across the site, the regression test was not significant p>0.05); and positively correlated, with tree stand basal area, the regression test was not significant p>0.05). Similar environment and habitats at comparable urbanization levels though in different towns contain similar birds’ species as shown by the comparative studies between Awka on one hand and Onitsha and Enugwu ukwu towns on the other that produced similar species, species richness and diversity, but different abundance. Urbanization creates new unsuitable environments for birds with increased light intensity, decreased temperature and humidity, and increases the wind speed. It showed an increase in light intensity and wind speed from the forest to the commercial area; and an increase in temperature from the commercial area to the palm plantation site. The forest had a slightly higher temperature than the commercial area and a lower temperature than the palm plantation. The study also showed a decrease in humidity from the palm plantation site to the commercial area. The forest had a higher humidity than the residential area and the business industiia1 areas, but a lower humidity than the palm plantation site, Birds’ abundance decreased with decreased temperature, increased humidity, increased light intensity and increased wind speed. These were the conditions prevalent during the rainy season, The discovery during the study of habitats such as the cassava (Manihot esculenta) farm that were avi fauna less or bird less, throws up a lot of future research questions on why such habitats should be bird less, what the importance of this could be for man and implication to bird conservation as a whole. The study showed that, in general, most species suffer the effect of urbanization, as it produced communities that were less evenly distributed and unstable.

TO VIEW THE FULL CONTENT OF THIS DOCUMENT, PLEASE VISIT THE UNIZIK LIBRARY WEBSITE USING THIS LINK, http://naulibrary.org/dglibrary/admin/book_directory/Thesis/11728.pdf

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