Nipple Location by Newborn Rabbits: Behavioural Evidence for Pheromonal Guidance

One of the major tasks confronting newborn mammals is to find the mother's nipples and suckle. This requires that the young respond appropriately to the presence of the mother, that they find and secure a nipple, and that they suck effectively. Most mammals having altricial young spend long periods of time with their newborn litters while assuming the nursing posture. Cats (SCHNEIRLA et al., 1973), dogs (RHEINGOLD, 1963) and rats (GROTA & ADLER, 1969) for example, spend up to 80% of the first few days post partum nursing. Doe rabbits are unusual in that they give their litters very little behavioural assistance to suckle. They leave their pups almost immediately after giving birth, and with occasional exceptions, only return to feed them approximately every 24 hours (VENGE, 1963; ZARROW et al., 1965). Furthermore, the daily nursing period only lasts from about 2 to 4 minutes (DEUTSCH, 1957; LINCOLN, 1974), during which does stand almost motionless over their pups (HUDSON & DISTEL, 1982). Rabbits are fugitive animals and heavily preyed upon. Presumably the less time does spend in their otherwise blocked nursery burrows, the less chance there is of predators trapping them there or finding the young (ZARROW et al., 1965). However, rabbit pups are born in a rather immature state. They are naked, have sealed eyes and outer ears and have poor motor coordination (GOTTLIEB, 1971). How the newborn pups are able to locate their mother's nipples and suckle in the brief time available each day is unclear, as their normal suckling behaviour has not been described.