Robbins, R. L., Sheridan, J. 2021. Effect of enclosure expansion on the activity budgets of eastern black-and-white colobus monkeys, Colobus guereza. Zoo Biology 40(2), 115-123.

Behavior is one of the most observable and informative indicators of animal welfare. This study used behavioral observation methodologies to evaluate the impact of an enclosure expansion on the activity budgets of a group of three eastern black-and-white colobus monkeys, Colobus guereza, housed at the Adelaide Zoo in South Australia. Instantaneous scan sampling methods were used to record the monkeys' behavior before and after they were given access to new aerial walkways at 2-min intervals between 8:30 a.m. and 4:30 p.m., over a total of 109 h (66 baseline hours, 43 post-expansion hours). Broad state behaviors (e.g., social, moving, resting, interacting, and feeding) were recorded and were used to generate activity budgets. Locomotion, feeding, and social behaviors increased following the addition of the aerial walkways, along with an overall increase in activity, attributed to the larger area and increased complexity of the environment. Results indicate that the addition of aerial walkways was effective for increasing the behavioral repertoire in colobus monkeys, aligning activity budgets more closely with their wild counterparts, and increasing active and affiliative behaviors.