To pace or not to pace? A review of what abnormal repetitive behavior tells us about zoo animal management

Performance of abnormal repetitive behavior (ARB) is noted in many captive wild species. ARB can be categorized into 2 basic forms: those whose aim appears to be to compulsively reach an inappropriate goal and those whose performance is linked to an inappropriate motor function. Although the negative welfare connotations of ARBs are well known, the precise reason for their performance remains the subject of debate. As zoos move forward in collection planning and to gather more evidence on the biological needs of the species being kept, the idea that ARBs may be part of a coping function adds more weight to arguments that some species may not be suitable for the zoo at all. Modern-day definitions of animal welfare tell us to measure the well-being of the individual based on its attempts at coping with its immediate environment. A failure to cope, and hence performance of ARB, is an objective and measurable welfare metric that may highlight which species are appropriate for captivity. As conservation pressures on zoos mount, and the need to take in more captive-naive species increases, research on why captive wild animals develop ARB can be used to inform practice. In this article, we aim to review the welfare issues across 3 basic categories of zoo animal (mammals, birds, and ectothermic vertebrates) and critique how research into ARBs can be used by zoos to promote wild-type behavior patterns by providing biologically relevant management and husbandry regimes, which allow animals the key components of control and choice over what they do and how they do it.