Abstract:
The breeding pattern of the grass rat, Arvicanthis neumanni,
was investigated in central Tanzania in 2002 ⁄ 2003. Nine
hundred and forty-seven animals were captured in three
age groups: juveniles, sub adults and adults. These age
groups were present in the population for an extended
duration, but there was an increase in the number of
sexually active individuals and juveniles 2–3 months after
the onset of the rains (December 2002–May 2003). A peak
in reproductive activity occurred between January and
April. Litter size ranged between 5.58 ± 0.42 and
6.1 ± 0.26 in two study sites. There were no significant
differences in the number of embryos implanted in the
right and left horns of the uterus of pregnant females
(t 22 = 0, P > 0.05 and t 36 = 1.68, P > 0.05, respec-
tively). Sex ratio of A. neumanni was not skewed to either
males or females. Breeding was seasonal and seemed to be
associated with seasonal variations in primary productiv-
ity, which relates to rainfall patterns.
