Some scientists speculate our finned friends are turning upon each other in a “tribal” war over over-exploited fish stocks.
It’s bullying bottlenose versus the smaller and timid harbour porpoises and Risso’s dolphins in their own version of the “Hunger Games”.
But not all the evidence supports this.
The bottlenose dolphins are not eating those they kill.
And they’re killing species of porpoises – such as the squid-eating Risso’s dolphin – that don’t even compete for the same food stocks.
So what’s going on?
“They could be doing it for fun,” dolphin expert Nick Tregenza told New Scientist magazine.
Bottlenose dolphins can be deadly creatures. They are fast. Agile. Intelligent. Their sonar can “detect” weak spots in their opponent, guiding their attack.
These qualities have long been lauded for the manner in which they are used to protect their young from predators such as sharks.
There are other signs of recalcitrant behaviour, too.
Dolphins in Cornwall have been seen to be picking up stones from the sea floor and lifting them to the surface – where they would throw them.
“They were thought to be throwing stones at seals on rocks not far away,” Tregenza said.
Speculation for the behaviour ranges from food wars through to a growing “cultural” trends among some dolphin pods that regards killing to be “fun”. It also could be an expression of frustration: Tregenza said the bottlenoses may have been trying to help the other, weaker, dolphins – only to become angry when they didn’t respond.
What are your thoughts?
