A team of international researchers is studying the possibility that the harassment of seagulls on whales, to peck your loins and thus feed on fat and skin, can cause stress in cetaceans. the data emerges of a study released by the Institute for the Conservation of Whales (ICB).
East the bird habit was defined as “micropredation” and reinforces the hypothesis that attacks may have contributed to the increase in the death rate of whales, registered between 2003 and 2013.
A comparative work was carried out with colonies in other parts of the world where there are no seagull attacks. “The study carried out in collaboration with international researchers reveals that southern right whales from Peninsula Valdés (Argentina), unlike those of Head of Bight (Australia), show a change in behavior and greater expenditure of energy due to the attacks of the seagulls”, they comment in the note.
Mariano Sironi, Scientific Director of the Institute for the Conservation of Whales and co-author of the paper, describes: “Although we have studied seagull attacks on right whales in the Valdés Peninsula since the 1990s, It’s the first time we’ve estimated the magnitude of behavioral changes caused by video-based attacks, and comparing them to an undisturbed population like that of Australia. ”
Unprecedented behavior in whales in the Valdés Peninsula
Thecontinuous bullying triggers a strong physiological response to stress. It was observed that, when attacked by seagulls, whales from Argentina reacts with quick and energetically expensive immediate movements, like arching your back, diving, speeding up your swim or hitting the water with your tail or fins.
It was also registered a strategy developed by the whales of Valdés to reduce the attack of seagullsThis is a breathing mode known as “oblique breathing”. Whales emerge from the water in an inclined position, lifting only their head and spiracles to breathe, but keeping their backs submerged.
The unnatural position causes them to struggle with their natural buoyancy, which can have a higher energy cost than normal breathing. Oblique breathing is only registered in the Valdés Peninsula and it has not been documented in any other whale population in the world, although there are occasional records of seagull attacks elsewhere.
energy expenditure it becomes important because whales fast while nursing their young. They do this with the milk produced in the reserves accumulated in the feeding areas, where they migrate in spring and summer. Using more “fuel” in evasive actions can lead to death from debilitation.
“Between 2003 and 2013, events of high mortality of right whale offspring were recorded in Peninsula Valdés, and although the exact causes have not been identified, one hypothesis suggests that seagull attacks may have contributed to this mortality”, the conclusions state.
Gull Sanitary Rifle
In 2012, Chubut implemented a “sanitary rifle” system against seagulls, which consisted of shooting birds when they landed on whales. Although it was touted as “a successful method of selective euthanasia”, it was in practical terms very ineffective and that’s why it was abandoned.
“It is impossible to shoot from a boat that passes through the waves at a seagull that is on the back of a whale, with the intention of killing the bird without harming the species to be protected”, explained the shooters that when they made the attempt.
Experts agree that the seagull population grew alongside the open dumps, where “served food” is offered to this species on the outskirts of the gulfs that form the peninsula.
The decision to kill the seagulls also provoked reactions from protectionist entities, which tried to act in dumps using nets to catch to the gulls that are identified as attackers and to the destruction of eggs to avoid a greater number of offspring.
.