Movement and spatial distribution of the Nile rat (Arvicanthis niloticus) in Kenya

Abstract

The movement and spatial distribution of marked Nile rats, Arvicanthis niloticus, was traced through phases of a low density population from January to August 1981, a rapidly growing population from September to January 1982, and a high and declining postreproductive population from February to April 1982. Apart from late in the population cycle there was considerable movement, interchange and establishment of new ranges. As the population increased individual ranges became smaller. The rats apparently preferred field edges and did not favour the fields themselves. Females frequently established themselves at certain sites where they produced their litters; some of the offspring remained with the mother in the warren. There is also evidence that ousiders of both sexes joined these warrens. Males were generally more wide-ranging than females. Agricultural practices, e.g. mowing and trampling by cattle, influenced the rats preparedness to remain within a particular location. Exploitation of all the available habitat took several months to achieve.

Ecology of small rodents in Africa

“…Females never joined the existing colony. This situation is different to that obtained by Delany & Monro (1986b), where there was stability of some individuals, movement of some animals of both sexes, additions of both sexes by immigration to colonies, and a surprisingly slow occupation rate of suitable new areas as the population expanded. By the late dry season, considerable restructuring of groups had been achieved.…”

“…T h e field situation is one of enormous numerical change through the breeding season with as a result territorial defence presumably becoming a progressively more demanding activity. This could be a factor in the decline of range witnessed at high densities (Muller, 1977;Delany & Monro, 1986b).…”

Effects of photoperiod on the reproductive condition of Nile grass rats (Arvicanthis niloticus) from an equatorial population

“…Arvicanthis niloticus is a small (60–130 g), group‐living, diurnal rodent inhabiting grassland and savanna ecosystems throughout much of sub‐Saharan Africa ( Kingdon, 1984 ; Delany & Monro, 1985 ). A. niloticus , in this experiment, were members of a laboratory colony descended from 29 animals trapped during July and August 1993, at two locations 20 km apart in the Masai Mara National Reserve, Kenya (2°S, 35°E, elevation 1525 m).…”

Diet, seasonal abundance and microhabitats of Praomys (Mastomys) natalensis (Rodentia: Muridae) and other small rodents in a Kenyan sub‐humid grassland community

“…Adjusted range lengths were determined for Praomys to describe the species ranging patterns (Stickel, 1954;Delany & Monro, 1985). This involved the measurement of the distance between the most widely separated capture sites and the addition, to each end of the line, of one half the distance to the next trap.…”