Cage level has little effect on behavior of macaques (M. fascicularis, M. nemestrina, and M. mulatta) (2004)

Bentson, K. L., Crockett, C. M., Montgomery, H. B. et al.

Abstract

Monkeys are commonly housed in two-tiered caging, which is more economical than single-level cages. Some animal welfare advocates maintain that inhabitants of lower-level cages experience compromised welfare, and experiments may be impacted if behavior and/or physiology varies by cage level. While testing the temperament of 318 monkeys, we assessed time spent in front third of cage (Front) and engagement in five activities: scratching, grooming, eating, manipulating objects, and locomotor stereotypy, a possible indicator of compromised well-being. An observer not known to the monkeys in any other capacity made observations from the middle of the room (Phase 1, 4 min) followed by observations while standing directly in front of each subject's cage (Phase 2, 4 min). Each monkey was tested twice. We used repeated measures GLM on the Test 2 data to investigate effects of the independent variables Phase, Tier, Species, Sex, Age, and Time in Colony. There was a Tier effect only for Front (p < .01; time in front third of cage greater for monkeys in top cages). Front was also affected by Phase, Species, Sex, and Time in Colony (each p <.0005). Frequency of engagement in the five activities did not differ by Tier but did differ by Phase, Species, Sex, Age, and/or Time in Colony. Cage level exerted less impact on the measured behaviors than the other independent variables.