Anuran Ecology in Relation Particularly to Oviposition and Development out of Water

This paper is a contribution to the poorly known subject of wild rodent behaviour. Observations were conducted in the field and laboratory on the vlei rat, Otomys irroratus, as part of a comprehensive study of its ecology and life history.

Individual behaviour, social behaviour, and post natal development are described and discussed. It was found that the vlei rat is very shy and retiring in captivity. It can be considered as crepuscular, but activity tests conducted in the field and laboratory indicated some activity throughout the day and night.

Interactions of adults were tested and they were found to be very antisocial, with intrasexual aggression occurring when caged. Complex threat and communication patterns exist, a feature of asocial behaviour. Mating failed to occur in captivity, probably also a result of their antisocial nature.

Marking behaviour is very distinctive in this species and, combined with urination and possibly defecation, would appear to be useful in delimiting territories. It is concluded from their social habits, marking behaviour, and considerable overlap of home ranges that in nature their interactions with conspecifics are represented by a dominance hierarchy.

Several litters of young were reared. They are very precocial at birth and development proceeds rapidly. At birth the incisors are erupted, enabling them to cling firmly to the nipples of the mother. Most adult behaviour patterns are developed before weaning at 13 days.