POPULATION BIOLOGY OF THE MULTIMAMMATE RAT,
 PRAOMYS (MASTOMYS) NATALENSIS
 AT MOROGORO, TANZANIA, 1981- 1985



 Sam R. Telford, Jr.*





 ABSTRACT


 The population of Praomys (Mastomys) natalensis on the campus of Sokoine University of
Agriculture in Morogoro, Tanzania, was studied by monthly samples from October 1981 to
February 1985. All 35 individuals that were karyotyped had a diploid number of 32
chromosomes. An annual species, the breeding season of P. natalensis normally begins in April,
with three or four litters of 3-23 young each produced by the end of August when reproduction
ceases. The average litter size was 11.7; females smaller than 105 mm HBL produced 1-2
embryos fewer than those larger ; maximum litter sizes averaging 12.0-12.6 were produced by
females 120-129 mm HBL. The actual number of young born was probably around 10.6 per litter,
due to resorption of 0.4-3.2 percent of embryos produced. Testes of adult males regressed from
September through November; spermatogenesis began in December and was completed by
February for young of the year and those adult males which survived into the next breeding
season. Off season breeding can occur in fallow maize fields in January or February, apparently
governed by the precipitation level during the short rains of November, and is limited to
production of a single litter before the regular season begins in April. Young produced during
this period reached maturity by April. Praomys natalensis comprised nearly 87 percent of the
9306 rodents and insectivores trapped on the university campus. Trap success was maximum
following reproduction, from September to December, declining thereafter until May when
recruitment of young to the population began again. The maximum recorded density was 1125
per ha, in October 1984. The population structure and density are influenced by both habitat and
rainfall. The critical factors which determine population levels following the main breeding
season are apparently heavy short rains followed by off-season breeding which alter the density
threshold at which the population begins reproduction in April.






* Denmark-Tanzania Rodent Control Project, University Campus, P. O. Box 3047, Morogoro, Tanzania.
Current Address: Adjunct Curator, The Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA
32611.

TELFORD, S.R., JR. 1989. Population Biology of the Multimammate Rat, Praomys (Mastomys)
natalensis, at Morogoro, Tanzania, 1981-1985. Bull. Florida State Mus., Biol. Sci. 34(6):249-287.