The Impacts of a Commercial Bubble Curtain on Zoo-Housed African Penguin (Spheniscus demersus) Swimming Behavior

Swimming is an important behavior for all penguin species. However, zoo-housed penguins typically do not swim as often as their wild counterparts, which may have consequences for their health and welfare. In an effort to increase the swimming time of the African penguin (Spheniscus demersus) population at Lincoln Park Zoo in Chicago, IL, USA (21 adults: 13 males, 8 females), we introduced a commercially available bubble curtain to the outdoor pool within the penguins’ habitat. The bubble curtain pushes pressurized air out through a hose fitted with small holes to create a stream of bubbles that generate water movement, which could entice penguins to swim. Over the course of 2 months, the penguins were exposed to a series of alternating conditions characterized by the bubble curtain being off or on for 2-week periods. A total of 228 swimming bouts were observed during this study. The bubble curtain did not increase the amount of time the penguins spent swimming, nor the maximum number of penguins in the pool during swim bouts. Rather, the penguins spent more time swimming when the bubble curtain was turned off, and the number of penguins in the pool during swim bouts was consistent across experimental phases. Additionally, we found that penguins swam the most when air temperatures were between 31 and 40 °F (approximately −1 to −4 °C). Unexpectedly, at least three individual penguins swam overnight between the hours of midnight and 6:00, highlighting the value of monitoring animals during entire 24 h periods. Collectively, this study provides detailed information about the swimming behavior of a zoo-housed African penguin population, and indicates that a bubble curtain was ineffective at stimulating swimming.