Reproduction in Didelphis marsupialis and D. albiventris in Colombia

Specimens of Didelphis marsupialis and D. albiventris were collected from four habitats in central Colombia during 1967 to 1971. The main series were obtained of D. marsupialis in the llanos orientales at altitudes up to 500 m and in the Vallé del Cauca at 1000 m, whereas smaller series of both species were collected in low montane forest at 1600 to 2000 m and of D. albiventris in high montane forest at 2700 to 3300 m. In the llanos, breeding began in January at the start of the dry season and second litters were born in April to May but no females bred in September to December. The litter size was 6.5 ± 1.2 (S. D.) and there was no evidence of mortality during pouch life. However, there was a lower proportion of immature young than would be expected from this, so that mortality of newly independent young may be high. In the Vallé del Cauca, breeding commenced in January with second litters in April or May, but third litters in August also occurred. The litter size was 4.5 ± 1.4, the smallest recorded for any sample of Didelphis. The small series of D. albiventris is insufficient to determine the extent of the breeding season but the average litter size for 10 litters was 4.2 ± 1.4. Two collections of D. marsupialis from 23° S are re-examined with additional data and the results for South America compared to those from Central and North America. The correlations between latitude and litter size and breeding season previously reported for D. virginiana are seen to hold for D. marsupialis near the Equator and to be reversed in southern latitudes.