Authors : A. I. Adeyemo , T. J. Orsar , E. A. Agbelusi, O.A. Bello-Olusoji , M.O. Afunmiso and Y.M. Bankole
Abstract: A research was carried out at the University of Agriculture Makurdi located in the Guinea savannah of Nigeria, to examine the trend in some aspects of population ecology of Nile rat-Arvicanthis niloticus. Three habitat types comprising one plot of arable land for maize production, another plot of arable land for rice/sorghum production and a plot of uncultivated woodland were used for the field study. Three consecutive days in each month were used in observing rat activities in each plot. The study lasted for two dry seasons and two wet seasons making up 24 months. Activities of the rats observed in a 20 m-width strip in each plot include: construction of runways, nests and food remains left on the feeding sites. A total of 72 observation-days per plot were taken for the period of two years. Incidental samples of the rat population in the study sites were taken from January to February of the two-year study period. The data obtained was subjected to analysis of variance at p (%=0.05) significant level. The result showed that mean number of runways increased from 6.00/strip in woodland to 12.00/strip in rice/sorghum plot, while the mean number of food remains increased from 4.50/strip in woodland to 8.83/strip in rice/sorghum plot. Mean number of nests increased from 2.17/strip in maize plot to 5.71/strip in rice/sorghum plot. There was however, no significant difference (p>0.05) in the rat activities between habitat types though the general trend showed an increase in the activities from woodland through maize plot to rice/sorghum plot. Nile rats mean population/plot increased significantly (p<0.05) from 30.00 rats in woodland/plot through 46.77 rats in maize plot to 93.11 rats in rice/sorghum per plot. Population density increased from 3.57 rats/ha in woodland through 5.65 rats/ha in maize plot to 6.21 rats/ha in rice/sorghum plot. The rat density was significantly higher (p<0.05) in rice/sorghum plot than in woodland plot, but not significantly higher (p>0.05) than the one in maize plot. The number of rat activities increased significantly (p<0.05) in the early dry season (October, November and December), but diminished in the late dry season and crashed in the early wet season (Apr, May and Jun). Reproductive cycle was observed to be seasonal and closely associated with the rains reaching the peak in the early dry season (October, November and December). It however ceased in late dry season (Jan, Feb, and Mar) as the sampled population showed absence of newly born and juvenile rats at this period. An implication of this observation for management of wild population of the rats was discussed.
A. I. Adeyemo , T. J. Orsar , Agbelusi, E. A. , O.A. Bello-Olusoji , M.O. Afunmiso and Y.M. Bankole , 2005. Some Aspects of Population Ecology of Nile Rat-Arvicanthis niloticus in theGuinea Savannah of Nigeria . Journal of Animal and Veterinary Advances, 4: 818-824.