BULLETIN FLORIDA STATE MUSEUM VOL. 34(6)


 INTRODUCTION


 The multimammate or shamba rat, Praomys (Mastomys) natalensis
(Smith 1834) is distributed as a species complex throughout virtually the entire
African continent below the Sahara. Although other species may have greater
significance in given localities, P. natalensis is the most important indigenous
species to public health and agriculture in Africa. Field studies on its biology
in East Africa are surprisingly few, in view of the economic importance of the
species. It has been reported to undergo periodic explosive increases in
numbers (Harris 1937; Taylor 1968), yet no study based upon adequate
numbers of individuals, taken at regular intervals over a substantial sampling
period is available. Most studies were conducted over less than two years, and
virtually none examined a thousand animals or more. Valuable information on
P. natalensis as part of small mammal communities in Kenya, Uganda, Malawi,
and Zambia was presented by Southern and Hook (1963), Hanney (1965),
Delany and Kansiimervhanga (1970), Sheppe (1972), Taylor and Green (1976),
and Delany and Roberts (1978). Only three papers present data derived from
Tanzanian populations: Harris (1937), Chapman et al. (1959), and Hubbard
(1972). In none of these studies was the specific identity of the P. natalensis
population precisely ascertained, although this may become obvious in the
future when adequate data are available on karyotype distributions in East
Africa.
 The most valuable studies on the population biology of P. natalensis,
using an autecological approach, were those conducted by South African
workers (Coetzee 1967, 1975; Isaacson 1975). These have been supplemented
by observations on behavior (Veenestra 1958), postnatal development
(Meester and Hallett 1970), and community relationships (De Witt 1972).
Although there are the expected similarities in the biology of South African P.
natalensis to populations of the species in Tanzania, as discussed below, the
climatic factors which govern population dynamics between the two regions are
quite different, especially with respect to reproduction. Understanding of the
variability in reproductive response to local, seasonal, and annual variations in
climatic factors such as precipitation is critical to the development of effective
control programs.
 In 1980 the Danish International Development Agency (DANIDA)
established the Denmark-Tanzania Rodent Control Project at Morogoro,
Tanzania. One of the objectives of the Project was to obtain, through suitable
long-term field studies, an understanding of the population biology of P.
natalensis adequate to assist in the design of a national control program
appropriate to the Tanzanian environment and economy. With my arrival as