Abundance, Diversity And Distribution Of Small Mammals In Oloolua Forest, Nairobi, Kenya

Abstract

Nairobi’s fast growth as an urban center has posed various negative challenges to fauna and flora. The future of small mammals is especially bleak considering their specific ecological needs which are easily affected by habitat alteration. The purpose of this study was to assess the abundance, distribution and diversity of small mammals in Oloolua forest; the seasonal variation in captures of small mammals; as well as the effect of habitat structure on the abundance and distribution of small mammals. Four habitats were sampled for 90 days during the dry and wet seasons of the year 2017. Rodents and shrews were captured using a mixture of traps, small carnivores were sampled using tomahawk cage traps whereas bats were captured using mist nets. The traps were placed randomly in transects that were systematically positioned in each habitat. A total of 217 small mammals belonging to three orders, Rodentia (43.78%), Soricomorpha (2.76%) and Chiroptera (53.46%) were captured. The diversity index of the small mammals was higher in disturbed habitats (Shannon_H'=1.594) than in the undisturbed habitats (Shannon_H'=1.477); and captures were less in the undisturbed habitats (101) as compared to those in the disturbed (116). A one-way analysis of variance on the abundances across the habitats yielded F(3, 35) = 0.5209 P >0.05 indicating that there was no significant difference in the abundance of small mammals among the four habitats sampled. Overall captures across the dry and wet seasons also showed no significant difference, t (9) = -0.03939 P>0.05. There were significant differences in the results of each of the habitat variables studied even though they did not influence the abundance, diversity and distribution of small mammals across the habitats. This study confirms that small mammal abundance, diversity and distribution in Oloolua forest is uniform across all its habitats as had been hypothesized. It also highlights the importance that surveys of small mammals in urban green spaces have towards highlighting the effects of climate change on the dwindling yet very important urban ecosystems.