2012/05/02

Pulpo ornitófago en las costas de la Columbia Británica (Pacífico canadiense)

Iturria: Birdfellow.com


Who’s up for lunch? A Gull-eating Octopus in Victoria, BC

By Ann Nightingale
One of the great things about being a nature lover is that your powers of observation seem to improve. While others are walking by, oblivious to the activities going on all around them, naturalists notice the creatures and the behaviors, especially if they are out of the ordinary.
Ogden%20Point%20Breakwater%20-%20Craig%20Spence
The Ogden Point Breakwater is a popular spot with folks out for a weekend stroll. (Photo by Craig Spence, sourced online at Flickr.com)
Such was the case on March 24, 2012, a sunny Saturday morning, when Ginger Morneau, her husband Ken, and brother Lou Baker were walking along the Ogden Point Breakwater in Victoria, BC. The breakwater is a favourite spot for locals and visitors, reaching out about a half mile from the waterfront south of downtown. The area is also popular with divers as it is a marine park, populated with interesting fish, marine plants and invertebrates. Walkers strolling along the top of the breakwater can often see marine wildlife in the water below.
As the group headed out along the walkway, Ginger noticed a gull acting strangely a short distance ahead of her. The bird was on the inside of the breakwater, where the water is clear and can be quite still. The gull appeared to be feeding on something underwater, but it didn’t raise its head. As they approached, they could see a red-orange shape in the water below the gull. When they got to the spot directly above the gull, they could see that it was an octopus. And Ginger’s camera was in her hand.
The Giant Pacific Octopus can be seen regularly patrolling the shallows of the shorelines around Victoria. They primarily feed on crustaceans, but are known to occasionally take fish and even birds. Octopi are extremely intelligent animals, and great problem solvers. Although they live only about four years, they can grow to have a span of more than 20 feet and to weigh more than 100 pounds. This one wasn’t that large, but it was still an impressive individual. What was even more impressive, though, was that it had one of its tentacles wrapped around the head of the gull, holding it under water.
image001
When first spotted, it appeared that the young Glaucous-winged Gull was feeding on something just under the surface...but on further inspection it became clear that the gull was was the prey item. (Photos by Ginger Morneau)
image003
The first winter Glaucous-winged Gull was struggling, flapping its wings in an attempt to break the octopus’s grip, but without success. The octopus’s eight tentacled arms allowed it to cling firmly to the rocks and simultaneously maintain its grasp on to the gull. Initially, air was bubbling to the surface, but within a minute, the struggle was over. More tentacles came out of the water to grab the body of the gull and pull it completely under. Other gulls flew overhead, noisily checking out the scene as if to see if there were going to be any scraps, but disappeared once the victim had been pulled from the surface.
image004
In less than one minute the gull was drowned, fully submerged and appeared to partially ingested with only its wings still visible. (Photos by Ginger Morneau)
image005
Ginger described the battle as “primal” and although she wanted to rescue the gull, it wouldn’t have been possible due to the sheer drop from the walkway–not to mention that the writhing tentacles of the octopus were more than a little intimidating. So she snapped a few more pictures, aware that she was witnessing a rarely-seen event. There wasn’t time for more–from her first picture to her last, only 53 seconds had elapsed. A couple of others watched the spectacle, but most people just walked on by, unaware of the struggle just fifteen feet below them.
Gulls will eat octopus, given the opportunity. There’s a decent possibility that the victim in this story might have even been pecking at the octopus before Ginger and her family happened by. We’ll never  know who started this battle, even though we definitely know who won! There are other records of octopus catching and eating sea birds, including reports of one with a den near a boat ramp on Whidbey Island that was seen catching both gulls and Pigeon Guillemots. However, Ginger’s are the only photos we’ve found that document this behavior.
To commemorate witnessing and photographing this amazing event, Ginger, Ken and Lou went out for a calamari lunch.
Literature Cited:
Mather, Jennifer A., Roland C. Anderson and James B. Wood (2010). Octopus: The Ocean's Intelligent Invertebrate (2010).
Sazima, Ivan and Lisandro Bastos de Almeida (2008). The Bird Kraken: Octopus preys on a sea bird at an oceanic island in the tropical West Atlantic. Marine Biodiversity Records, 1 , e47 doi:10.1017/S1755267206005458

No hay comentarios:

Publicar un comentario