THE EFFECTS OF CAGE SIZE AND COMPLEXITY ON THE BEHAVIOR OF CAPTIVE COMMON MARMOSETS, CALLITHRIX-JACCHUS-JACCHUS

Conditions of captivity of primates used in biomedical research may ha ve deleterious effects on the welfare of the animals and consequently on the reliability of the research. We investigated the effects of cag e size and cage complexity, two fundamental characteristics of captive conditions, on the behaviour of the common marmoset (Callithrix jacch us jacchus). We found an increase in the general level of activity and significant variation in the frequencies of specific behaviours with an increase in cage size and also with cage complexity. Stereotyped be haviours, which occurred in the small cages, were never exhibited in t he large cages. The effect of the novelty of the changed conditions wa s also assessed and found to be significant for some behaviours. We al so measured the time taken to capture Bn animal, a task frequently per formed by the animal technician, under the various cage conditions. Ca pture time increased significantly in the larger cages, but the overal l effect of the changes to the marmosets' housing conditions on the an imal technician's work was not regarded as substantial. We conclude th at the welfare of captive marmosets is enhanced by the provision of la rger and more complex cages, and that such cages do not significantly affect the efficiency of the research laboratory.