Audible signals during intolerant behaviour of Rattus fuscipes

Abstract

The social behaviour of the Australian bush rat, Rattus fuscipes, was observed in the laboratory. All rats had been trapped as adults. In each encounter a male or female intruder was put in a cage containing an established male or female resident; the movements of the animals, and the sounds they made, were recorded for 10 min. The behaviour patterns of the two sexes were similar. The principal sounds were: (1) a whistle, or pure monosyllabic note (fundamental about 2.5 kHz); (2) a scream, or fluctuating multisyllabic sound; (3) intermediates between these two; (4) a cough (rare); (5) tooth-chattering (not voiced). Whistles, screams and intermediate sounds accompanied attacks and associated behaviour: during approach or threat only the animals approached or threatened made these sounds; when the animals were in contact, both did.