RESEARCH ARTICLE Perception of Available Space During Chimpanzee Introductions: Number of Accessible Areas Is More Important Than Enclosure Size Elizabeth S. Herrelko, 1,2 * Hannah M. Buchanan-Smith, 1 and Sarah-Jane Vick 1 1 Psychology, School of Natural Sciences, University of Stirling, Stirling, Scotland 2 Animals, Education, and Conservation, Royal Zoological Society of Scotland, Edinburgh Zoo, Edinburgh, Scotland Restricting animals to different areas of their enclosure, for both brief and extended durations, is a key element of animal management practices. With such restrictions, available space decreases and the choices the animals can make are more limited, particularly in relation to social dynamics. When unfamiliar individuals are introduced to each other, group dynamics can be unpredictable and understanding space usage is important to facilitate successful introductions. We studied the behavioral, welfare-related responses of two groups of zoo-housed chimpanzees (n ¼ 22) as they were introduced to each other and experienced a variety of enclosure restrictions and group composition changes. Our analysis of available space while controlling for chimpanzee density, found that arousal-related scratching and yawning decreased as the number of enclosure areas (separate rooms) available increased, whereas only yawning decreased as the amount of available space (m 2 ) increased. Allogrooming, rubbing, and regurgitation/reingestion rates remained constant as both the number of enclosure areas and amount of space changed. Enclosure space is important to zoo-housed chimpanzees, but during introductions, a decrease in arousal-related scratching indicates that the number of accessible areas is more important than the total amount of space available, suggesting that it is important to provide modular enclosures that provide choice and flexible usage, to minimize the welfare impact of short- and long-term husbandry needs. Zoo Biol. 34:397–405, 2015. © 2015 Wiley Periodicals, Inc. Keywords: enclosure size; animal welfare; captivity; chimpanzee; zoo INTRODUCTION An important element in the captive management of animals is safely moving groups between enclosure areas to allow care staff to provide for the animals’ needs [Hosey et al., 2009]. Husbandry requirements may temporarily limit animals to off-exhibit areas for cleaning or maintenance purposes [e.g., Ross et al., 2010] and sections of enclosures might be closed off on a long-term basis for major events such as animal introductions [e.g., Schel et al., 2013]. Additionally, zoos in temperate climates have to deal with the challenges of temperature fluctuations and inclement weather, prompting animal care staff to occasionally limit animal access to indoor areas (e.g., when moats freeze over [de Waal, 1982]). Even when access is permitted during inclement weather, animals may choose to stay indoors [Ross et al., 2011]. As a result, the space (m 2 ) and number of available enclosure areas (separate rooms) often change. This may lead to shifts in behavioral and social opportunities, making it important to understand the impact of short- and long-term spatial restrictions on animal welfare. Individuals often indicate strong location preferences; however, suggest- ing that having a choice of locations may be more important Grant sponsor: University of Stirling; Burning Gold Productions. Conflicts of interest: None  Correspondence to: Elizabeth S. Herrelko, David Bohnett Cognitive Research Fellow, Smithsonian’s National Zoo, Animal Care Sciences, P.O. Box 37012, MRC 5507, Washington DC 20013-0712. E-mail: bherrelko@gmail.com Received 23 June 2015; Accepted 07 July 2015 DOI: 10.1002/zoo.21234 Published online 30 July 2015 in Wiley Online Library (wileyonlinelibrary.com). © 2015 Wiley Periodicals, Inc. Zoo Biology 34: 397–405 (2015)