Researchers are still uncertain about the exact reasons why bottlenose dolphins are attempting to harass, butt, and even bite young Antillean manatees.
The dolphins are attacking young manatees, and this aggressive behavior may be occurring more frequently than previously thought. In a study published in the journal PLOS One, scientists documented 10 aggressive interactions of bottlenose dolphins (Tursiops truncatus) with young Antillean manatees (Trichechus manatus manatus). They often targeted orphaned calves as well as individuals swimming with their mothers. These attacks occurred near Belize over a period of 21 years, from 1999 to 2020, with most incidents concentrated between 2015 and 2020, Live Science reported on January 22.
Bottlenose dolphin attacking a young manatee. (Photo: PLOS One).
“Dolphins do not eat manatees, and the reason for their behavior towards this species remains unclear“, said Eric Angel Ramos, the lead researcher and a scientist at the International Foundation for Nature and Sustainable Development (FINS), which specializes in conservation. “They may be quite curious when encountering manatees. Since dolphins are often aggressive towards each other, they may also exhibit this behavior towards other species like manatees.”
The research team observed dolphins attempting to separate young manatees from their mothers, harassing, butting, and biting them. In each case, the dolphins were actively interacting. The researchers believe that their attacks are intentional. Ramos and his colleagues found tooth marks matching those of dolphins on orphaned calves during health checks at a rehabilitation center, providing additional evidence of aggressive behavior.
While scientists do not fully understand what is happening, dolphins exhibit similar behavior towards their own calves and other species. Previous studies have documented dolphins biting conspecifics and attacking and killing harbor porpoises (Phocoena phocoena).
Dolphins may act aggressively towards manatees and other marine animals because they view them as competitors for food, territory, or resources. If the ecosystems of these animals deteriorate due to climate change and human activities, their habitats may increasingly overlap, leading to heightened aggressive behavior.
Bottlenose dolphins are intelligent creatures. They have large brains and exhibit a range of complex emotions, including grief. The interactions between dolphins and manatees have been occurring for many years and are more common than scientists had previously assumed, posing a threat to the survival of the species. Antillean manatees are endangered throughout their range. This subspecies of West Indian manatee inhabits freshwater, brackish, and marine environments from southeastern Texas to northeastern Brazil. Even around Belize, they are also at risk from vessel collisions.
