Behavioural responses of captive marmosets to environmental enrichment (2001)

Pines, M. K., Rogers, L.

Abstract

This paper will report a study aimed at improving caging design for common marmosets (Callithrix jacchus). Evaluation of the effects of different internal cage designs on activity and other behavioural measures of marmosets were examined. Twelve subjects were tested, 6 males and 6 females. Each marmoset was tested individually for an hour in four separate cage designs providing different structures for climbing and locomotion. The four designs were (1) vertical bars, (2) horizontal bars, (3) vertical and horizontal bars, and (4) the same number of bars as in (3) but placed at various angles to each other. The subjects were tested in random order over four consecutive days. The number of vocalisations, parallax movements (used in depth perception) and self-grooming bouts were recorded using videotaping via a one-way mirror. The type of surface on which the subjects were located was recorded using one-minute interval sampling. Changes in position within the cage were scored using one-minute interval sampling and this was used as a measure of locomotor activity. The marmosets used the horizontal bars significantly more often than the vertical bars. They were significantly more active in conditions (2), (3) and (4), the cages with horizontal bars, than in (1). Activity was greatest in condition (4). The marmosets were approximately 60 % more active in condition (4) compared to condition (1). Females were significantly more active than the males and showed greater preference for the bars. These results are consistent with previous reports of higher levels of exploration in females of a number of primate species. Males used the nesting box more than the females. The different cage conditions did not effect the amount of parallax movement, self-grooming or vocalisation. The results suggest that a caged environment for marmosets should have horizontal and diagonal bars and that they do not utilise vertical bars. For males especially, a nesting box should be present. These results are consistent with behavioural studies of wild marmosets by Lacher et al. (1984), who reported that marmosets spend the majority of their time on the branches and trunk which tend to be more diagonal and horizontal than vertical.