[The biology of the volcano mouse (N. a. alstoni). XXI. Reproductive capacity of wild females in 15 successive matings].

This study comprises an investigation on the reproductive capacity of wild females of the volcano mouse (Neotomodon alstoni alstoni), in 15 successive matings. The neotomodon were captured in the Sierra del Volcán Ajusco (Cerro Pelado, Parres, D.F.). The animals were kept under environmental laboratory conditions, being fed ALBI-LAB pellets and tap water. The matings were performed from may 1985 to August 1988 by pairs and at random, during 12 days. The females were weighed on the day 1 of the mating; the young were sexed on the 7th day of life, and weaned at the 30th day of age. The results were: the mean of the percentages of pregnancy in the 15 matings was 39.6 +/- 3.0, being the highest percentages in Spring-Summer. The size of the litter varied from 1 to 6 young, with a mode of 3 and a global average of 2.7. The means of the percentages of survival at the first week of life and at weaning were 72.9 +/- 3.6 and 70.3 +/- 3.3, respectively. The proportion males-females was 1.2:1. There was not found a significant positive correlation between the weight of the mothers at day 1 of the mating and the size of the litter (r = 0.65, p less than 0.05). These results allow to conclude that in the laboratory the wild volcano mouse exhibits a high reproductive capacity, which demonstrates that this rodent posseses very positive qualities in order to make out of him a new experimental animal.