TREE SQUIRRELS IN THE GENERA FUNISCIURUS AND PARAXERUS

Postnatal 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 cong{cus. 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. cong{cus; 1.98 _+ 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 (85 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. Although Africa harbors species of squirrels from the genera Heliosciurus, Aethosciurus, Funisciurus, Myosciurus, Epixerus, Proxerus, and Paraxerus (Amtmann, 1964), little is known of their biology. The only comprehensive studies have been those of Emmons (1975) in Gabon and Viljoen (1975, 1978, 1980) in southern Africa. Dobroruka (1970), Rahm (1970), and Kingdon (1974) provided additional information on the squirrels of East Africa. Four taxa of three squirrels occur in South West Africa/Namibia, Botswana, and South Africa: the Western striped squirrel, Funisciurus congicus, in arid savanna of north-western South West Africa/Namibia; the yellow-looted bush squirrel, Paraxerus cepapi, in north-eastern South West Africa/Namibia, northern and eastern Botswana, and in the north of the Transvaal Province of the Republic of South Africa; the Tonga yellow-chested squirrel, P. palliatus tongensis, on the southern tip of the Mozambique plain in subtropical xeric to mesic coastal forests; and the Ngoye red squirrel, P. p. ornatus, also on the eastern seaboard, but isolated in the evergreen, moist subtropical Ngoye forest which covers an area of 2,984 ha. The purposes of this study were to document growth rates of the above four taxa of tree squirrels and to compare their postnatal development, litter sizes, and gestation periods with those of other tree squirrel species. The subspecies of P. cepapi studied was P. cepapi cepapi from Naboomspruit in the Transvaal. METHODS Five litters (n = 10) of F. congicus, one litter (n = 2) of P. c. cepapi (data from three litters (n = 7) from Viljoen (1977a) were included to increase sample size), three litters (n = 6) of P. palliatus tongensis, and five litters (n = 7) of P. p. ornatus were born to animals that bred in captivity. Parent squirrels were captured either as subadults or adults in the field and kept in Pretoria in outdoor cages varying in size from 7.5 m s to 82 m s. Most cages, each with two to five nestboxes, housed an adult pair. However, one cage of P. p. ornatus contained two males and a female, and another had two females and a male. All litters were born in the southern warm and rainy season. Breeding occurred only after the squirrels had adapted to captivity. P. cepapi and F. congtcus, the less-wild woodland species, bred after 2 and 5 months in captivity, respectively, whereas the forest species P. p. ornatus and P. p. tongensis bred only after 21 months and 26 months in captivity, respectively. Squirrels were fed ad lib. on chopped fresh fruit in season, fruit juice with multivitamin syrup, a nutrionally-balanced food cube, acorns, and a mixture of peanut butter, wheatgerm, Pro Nutro, honey, oats, sunflower oil, and seeds. Standard body measurements of neonates were taken daily during the first week after birth, if possible, and thereafter at 6-day intervals. Developmental stages were recorded daily during early postnatal devel- opment.