Postnatal Development and Growth of Southern African Tree Squirrels in the Genera Funisciurus and Paraxerus

Abstract

Postnatal growth curves of four taxa of subtropical tree squirrels are given for ear, hindfoot, tail, and total lengths, and for mass. The largest squirrel, Paraxerus palliatus ornatus takes longer to reach adult dimensions than do P. p. tongensis, P. c. cepapi and Funisciurus congicus. Litter size was significantly smaller in the two subspecies of P. palliatus (1.71 ± 0.49, n = 7 in P. p. tongensis; 1.60 ± 0.52, n = 10 in P. p. ornatus) than in the two species from savanna habitat (2.0 ± 0, n = 8 in F. congicus; 1.93 ± 0.59, n = 29 in P. c. cepapi). These litter sizes are smaller than those of Holarctic tree squirrels, the nestling period is also shorter (from 18 to 27 days) than in Holarctic tree squirrels (35 to 58 days), and developmental stages are reached earlier. Therefore, fewer but larger young are born, with the gestation period lengthened and the nestling period shortened. Early weaning results from a limitation of food resources rather than high mortality rate of the young.