Researchers from Nova Southeastern University in Florida and the University of Rhode Island studied the stingray population of Stingray City -- a sandbar in the Cayman Islands that draws nearly a million visitors each year to feed, pet and swim with its stingrays -- to assess how the intensive ecotourism has affected the animals' behavior.
The stingrays show distinctly different patterns of activity than their wild counterparts, who don't enjoy daily feedings or close human contact, the researchers reported in the journal PLoS One.
"We saw some very clear and very prominent behavioral changes, and were surprised by how these large animals had essentially become homebodies in a tiny area," Nova Southeastern researcher Mahmood Shivji said.
The tourist-fed stingrays swapped their normal nighttime foraging for daytime feeding, abandoned the species' normal solitary behavior to crowd together, and showed signs of aggression, biting each other more than their wild counterparts, he said.
That suggests that human-provided food can dramatically change how even large, highly mobile ocean animals behave, with potentially serious consequences, the researchers said.
"There are likely to be some health costs that come with these behavior changes, and they could be detrimental to the animals' well-being in the long term," Shivji said.
Stingray City generates a lot of tourist income for the Cayman Islands, researchers said, making understanding the affect on wildlife important.
"Measuring that impact is important because there's a lot of interest in creating more of these interactive ecotourism operations, but we know little about the life histories of the animals involved or how they might change," study co-author Guy Harvey of Nova Southeastern said.