Birth in the northern brown bandicoot, Isoodon macrourus (Marsupialia:Peramelidae)

Abstract

The ability of the newborn marsupial to move from the uterus to the pouch and locate the teat is still not fully understood. Birth has now been observed in a number of species of marsupial. However, filming this event, which occurs over a few minutes, allows for a greater understanding of the mechanisms involved. In this study, birth was filmed in 4 northern brown bandicoots, Isoodon macrourus. Before birth the bandicoot lay on one side with one hind leg facing upwards. The mother licked around the urogenital sinus, around the pouch and along the inside of the hind legs. There was no release of fluid just prior to birth of the first young, which appeared covered in membranes. The mother licked the young vigorously to remove the membranes. Young were born singularly or in groups of up to four young. Contrary to the situation in the red kangaroo the pathway of the newborn of the bandicoot was mainly downwards, with the newborn having to travel only about 1 cm to reach the pouch. The newborn of the bandicoot do not have a definite crawl to the pouch, as is seen in macropodids – they move with a snake-like wriggle down a moist 1-cm pathway between the urogenital sinus and the pouch. The mother bandicoot cleans the young, removing the membranes, and lies on one side then on the other, positioning the pouch so that the young nearly ‘fall’ into the pouch. As with the macropodids, the transfer from the urogenital sinus to the attachment to the teat in the pouch takes about 5 min. It is obvious that there are several marsupial ‘birth positions’, and several methods are used by marsupial species to allow the newborn to attach to the teat.