Otis came to the San Diego Zoo in January of this year, and after a brief quarantine period was introduced to Funani (see previous post, Enormous Changes for Hippos). Funani was less than thrilled about her new roommate and let him know it in no uncertain terms. After about three days together on exhibit, the decision was made to separate the pair.
During the interim, we worked diligently toward making the next introduction a successful one. First, Otis and Funani were given a “howdy,” an area where they could see, and interact, with one another without actually being able to come into contact. Second, we collected fecal samples from Funani. These samples were sent to the San Diego Zoo’s Institute for Conservation Research, where hormone levels were analyzed, giving us insight into Funani’s estrous cycle. This information would in turn enable us to determine when Funani was actually ovulating and would therefore be more receptive to Otis. Lastly, for extra insurance, we worked tirelessly on training Funani for tooth trimming.
Tooth trimming is a fairly routine practice for hippos in zoos, but Funani had not yet had any experience with such a procedure. Over the course of the past eight months, our dedicated staff trained Fu to stand still, open wide, and allow us to painlessly saw off the razor-sharp tips of her lower canines using a thin cable called a “giggly wire.” We accomplished this by using preferred foods as positive reinforcement in order for Funani to cooperate. If Funani decided she did not want to participate, we obliged and tried again another day. With these weapons blunted, the chances of Fu doing any serious damage to Otis would be minimized. It took a lot of patience, and special thanks go out to Manager Nicki Boyd, Supervisor Matt Akel, Lead Keeper Sue Averill, and Senior Keepers Dustin Black and John Michel for all of their work toward reaching this goal.
Finally, Fu’s teeth were trimmed and, based on behavioral observations in combination with our fecal sample study, we determined she was coming into estrus. Funani and Otis were videotaped the evening before they were introduced to ensure that Funani’s receptive behavior was accurate. The next morning the decision was made, and the pair was put together on exhibit. We watched as the two came nose to nose without a barrier for the first time in eight months. For the first half hour or so, the two hippos calmly stood face to face, at the bottom of their 150,000-gallon pool. Although quiet, it is quite possible that there was a lot of infrasonic (ultra low-frequency) communication occurring. After that first half hour, Funani was clearly submissive to Otis, and mating took place!
Since the introduction, they have been inseparable! If their breeding was successful, we should expect a newborn hippo come mid-June to early July. Clearly, patience, dedication, and a collaboration of animal care and research staff helped make this introduction a success.
Nate Schierman is a keeper at the San Diego Zoo. Read his previous post, New Okapi: Shh..It’s a Secret.