Abstract
There is a growing need for animal care institutions to house multiple bull elephants as the population increases due to transfers from private ownership and the births of male offspring in managed care. Elephants in North American, European, and Latin American zoos exhibit stereotypies—repetitive, fixed behaviors. Previous research demonstrated that housing Asian elephants alone increased stereotypic behavior. Therefore, for animals in managed care, social restriction can contribute to stereotypy and, by extension, reduce welfare. In this study, we examine how being alone affects stereotypic behavior by monitoring pacing and head-bobbing in individual bull Asian elephants at Denver Zoo when housed alone as well as with other bulls. Two young males arrived at Denver Zoo in September 2018 and joined an existing all-male group of three elephants that were previously socialized and housed together. From July 2018 to December 2019, we used instantaneous scan sampling to collect data on stereotypic behavior of focal bulls when they were housed alone and socially. The frequency of pacing and head-bobbing significantly decreased when the elephants were housed socially compared to when they were housed alone; these stereotypies were lower when elephants were housed with at least one other bull and were in close proximity to a conspecific. Additionally, pacing decreased as the proportion of affiliative behaviors increased, and the amount of agonistic behavior did not significantly affect stereotypic behavior. When housed alone, bulls in musth engaged in significantly more pacing behavior than when they were out of musth. Our results indicate that housing bull Asian elephants in all-male groups substantially improves their welfare by reducing stereotypies and provides a basis for future evidence-based management.
Highlights
Male elephants are known to regularly socialize, including with other bulls [1,2].of the 33 institutions participating in AZA’s Asian Elephant Species Survival Plan [3] at the outset of this study in 2018, only 18 were holding more than one bull and only three were routinely housing bulls together [4]
This study focused on a bachelor group of five bull Asian elephants housed at Denver Zoo, Colorado, USA [35,36]
Socialization, proximity, affiliative social interactions, study period, and musth substantially impacted the percentage of scans during which the elephants engaged in stereotypy
Summary
Male elephants are known to regularly socialize, including with other bulls [1,2].of the 33 institutions participating in AZA’s Asian Elephant Species Survival Plan [3] at the outset of this study in 2018, only 18 were holding more than one bull and only three were routinely housing bulls together [4]. This study examines how all-male socialization impacts stereotypic behavior among bull Asian elephants at Denver Zoo, Colorado, USA. Stereotypic behaviors are repetitive, fixed, and serve no discernable purpose [8]. In elephants, these behaviors can manifest as pacing, swaying, rocking, bobbing, or chain biting, among others [9,10]. These behaviors can manifest as pacing, swaying, rocking, bobbing, or chain biting, among others [9,10] Both semi-captive elephants in range countries and elephants in North American, European, and Latin American zoos exhibit stereotypic behaviors [9–11]. In many cases, these stereotypic behaviors persist for years, well beyond the existence of the original potentiating condition or event [10,12]. Stereotypy may be mitigated by housing elephants in social groups [9,10]
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