Growth and development of wild and captive Nile rats, Arvicanthis niloticus (Rodentia: Muridae)

Abstract

Summary Reproduction and post‐natal development of Arvicanthis niloticus was studied in the laboratory. The gestation period was 22–24 days with a post‐partum oestrus. Mean litter size was 3.7 ± 1.0. Young animals developed rapidly relative to other African murids and attained sexual maturity at 36–52 days. The growth of animals under laboratory conditions was compared with that of wild Arvicanthis in Kenya. Laboratory reared young gained up to 40g month‐1 while the maximum recorded in the wild was 30g month‐1. This rate was reduced during the dry season and adults virtually ceased growing at that time. A comparison of natural and laboratory growth curves showed the limitations of applying data obtained in the laboratory to wild populations. Résumé La reproduction et le développement post‐natal de Arvicanthis niloticus fut étudiée en laboratoire. La durée de gestation est de 22–24 jours avec un oestrus de post partum. La portée moyenne est de 3.7 ± 1.0. Les jeunes animaux se développent rapidement en comparaison d'autres muridés africains et atteignent la maturité sexuelle vers 36 à 52 jours. La croissance des animaux en conditions de laboratoire fut comparée avec celle d'Arvicanthisà l'état sauvage au Kenya. Les jeunes élevés en laboratoire croissent de 40 g mois‐1 alors que le maximum observéà l'état sauvage est de 30 g mois‐1. Ce taux est ralenti en saison sèche et les adultes ont une croissance pratiquement nulle à cette époque. La comparaison des courbes de croissance naturelles et en laboratoire met en évidence les limitations de l'application de données obtenues en laboratoire à des populations sauvages.

Population dynamics of Arvicanthis niloticus (Rodentia: Muridae) in Kenya

“…The capture of young animals in June and July 1981 shows that breeding was in progress at that time, but with the number of adults being low, the number of recruits was also low. Major reproductive recruitment did not occur until September, when those animals born earlier in the season were themselves old enough to breed (Delany & Monro, 1985~). It apparently ceased at about the end of the year.…”

“…Field and laboratory assessments were compared to establish the accuracy of the field observations. Animals have been found to attain maturity at about 45g for males and 40g for females (Delany & Monro, 1985~). Those below these weights were classified as immature and the rest as adults.…”

Movement and spatial distribution of the Nile rat (Arvicanthis niloticus) in Kenya

“…Its wide occurrence and economic importance have stimulated numerous studies on this animal in recent years (Delany & Monro 1985, 1986, Delany & Roberts 1978, Ghobrial & Hodieb 1982, Muller 1977, Neal 1981, Poulet 1982, Senzota 1982 1976). These have concentrated on topics such as population dynamics, life history strategies and feeding habits, with several authors recognizing the ability of this species to raise its population from very low to remarkably high densities over a few months.…”

Post-natal development and reproduction in captive bred Praomys albipes (Mammalia : Rodentia) from Ethiopia

“…The maximum weight obtained in the wild by Rupp (1980) was 83 g. In captivity, the weight record for many of reproductive active adults was between 50-60 g. It is possible that in the wild, variations in weight could result from different environmental factors. Delany and Monro (1985) obtained a difference of 10 g higher in captive bred Arvicanthis niloticus emphasizing the limitation of applying the data obtained to the wild populations. It is expected that in captive bred individuals, activity is limited and food supply is ample if accepted by the animal, resulting in less wastage of energy and build up of mass and fat.…”