|Killer dolphins may be born of frustration|
|Wednesday, 01 June 2011 17:33|
Seemingly random acts of violence by bottlenose dolphins on porpoises could be down to sexual frustration among young males.
Cases of the cetaceans killing other creatures for no apparent reason have been reported in UK waters. Now, bottlenose dolphins have been seen attacking harbour porpoises in the Pacific Ocean. Crucially, these observations, published in Marine Mammal Science, show for the first time that the attackers are young males.
Mark Cotter at Okeanis, a non-profit conservation organisation in Moss Landing, California, USA, and colleagues, observed three acts of aggression by dolphins on lone porpoises.
The dolphins chased the porpoises at high speed, rammed and then drowned them. In one particularly violent attack, three dolphins corralled their victim before seven others joined them to ram the porpoise to death. Cotter found most shocking the fact that two dolphins remained behind to play with the carcass before pushing it towards his boat.
“It was almost like they said: ‘We’re done playing with it, here you go’.”
Competition for food does not seem to explain the attacks, as the dietary overlap between the two species is small, said Cotter. But the fact that 21 of the 23 attackers were males may be revealing. He believes that the attacks are “object oriented play” during the breeding season by young males who cannot get access to females because of competition from older males.
“They are taking out their frustrations,” he said.
“The identification of the ‘culprits’ as male is valuable,” said Nick Tregenza, an adviser to the Marine Strandings Network in Cornwall, UK, and visiting researcher at the University of Exeter. That’s because it helps narrow down potential explanations for the behaviour, he said.
Cialis Side Effects is just like any other medication but do not need to worry and believe that everyone is bad. There is nothing surprising in this. All is simple and clear.
Latest Book Reviews
- The US Naval Institute on Naval Strategy
- Silent And Unseen: On Patrol in Three Cold War Attack Submarines
- 21st Century Seamanship
- Small Navies: Strategy and Policy for Small Navies in War and Peace
- The Baltimore Sabotage Cell: German Agents, American Traitors, and the U-Boat Deutschland During World War I
- Re-Inventing The Ship: Science, Technology and the Maritime World, 1800-1918
- The Indian Ocean and US Grand Strategy: Ensuring Access And Promoting Security
Latest CommentsLeonardo Alphonso: I am given to understand this book is useful for marine engineers for learning about purification of...
david wood ross: Excellent timely article Neil and accurately reflects my own experience. I say timely because recent...
Ross Fletcher: Well said.Needs a lot more noise on this issue. As a professional merchant navy Officer, I have been...
John Oscroft: Try the Barrow in Furness (UK) museum, housed in an old dry dock, whilst a lot is given over to the ...