Featured Image Credit: Leandro Stanzani
By Eva Gruber
The city of Adelaide, on the southern coast of Australia, is home to a group of bottlenose dolphins that reside in the city’s Port River. The River’s resident population numbers about 40, while up to 300 other dolphins may visit the area on a regular basis. The home of these dolphins is protected as part of the Adelaide Dolphin Sanctuary which encompasses a span of inlet and includes a 10,000 year old mangrove forest.
All of this is located just a 20-minute boat ride from Adelaide’s city center – proof that human settlements don’t have to negatively impact local wildlife. This proximity also means that a good amount of tourists take the time to go on river tours in hopes of spotting the famous dolphins. All the attention has contributed a lot of hours of observations, and the pods habits and behaviors are well known to locals and researchers alike.
One behavior became famous in the 1990s – tail-walking, a popular behavior taught to captive dolphins but one that has never been seen to occur naturally. In the late 1980s, one dolphin swam out of the Port River and was held at Marineland in Glenelg for a short time before being released. Billie, as she came to be known, learned to tail-walk from the other dolphins at Marineland. When she was released back into the wild she brought this learned behavior with her, and continued to do it. It seems that her pod members picked it up from her, and many members of the pod were then seen tail-walking on a regular basis.
When Billie died in 2009, it seemed that the tail-walking behavior died with her, and it hadn’t been observed in the Port River dolphin pod since. However, last weekend dolphin conservationist Jenni Wrysta was surprised to observe several individuals tail-walking again. In fact, while tail-walking once or twice is normal, one dolphin named Bianca was seen tail-walking 33 times in a row in sets of twos and threes!
Ms Wrysta does not understand why there would suddenly be a resurgence of this behavior, but she noted that the dolphins have seemed to be more social lately – congregating in groups of up to 10 dolphins rather than the usual four or five. The Port River also seems to be especially productive at this time of year. With more fish for the dolphin to eat, they may be spending less time foraging and more time socializing and playing. Whatever the reason, tourists will get a kick out of seeing this behavior again.