In order to be successful and have high standards of animal welfare, modern zoos strive to regularly modify, improve, and build animal enclosures and visitor areas. However, these periods of development could result in temporary durations of sub-optimal welfare for animals housed nearby. In this study, we monitored the behavior of three Asiatic lions (Panthera leo persica) prior to, during, and following a period of construction on a nearby building. Our results provide evidence that welfare may have been temporarily reduced during the construction period. Compared to the pre-construction period, the male exhibited an increase in pacing behavior and all three lions reduced the time they spent resting. We infer that the most significant negative stimulus related to the construction was sound and/or ground vibrations, as a physical barrier ruled out stress from visual stimuli. The behavioral response to the construction work was relatively short-lived and no long-term changes were observed one year on. This research highlights the importance of measuring animal behavior around events outside routine husbandry, and considering animal welfare on an individual basis. Finally, this work adds to the body of literature surrounding the impacts of construction on animal wellbeing and outlines some suggestions for potential mitigation.