Every time I go out fishing, I’m amazed at how quickly marine mammals (mostly sea lions) and seabirds find us and the feeding opportunity that our fishing boat represents. While we fish, a deckhand is usually on top of the bait tank, chumming the water to attract fish. Anglers catch fish that are either undesirable species or too small and wind up throwing them back. On the way home, the deckhands fileting the fish are throwing carcasses in the water. These are all great feeding opportunities for birds. I sometimes wonder whether these birds ever go out and actually hunt for themselves. Have they adapted to our being there to the point that they don’t really have to forage on their own?
Well, the same question must have occurred to more scientific types than your truly. Recently, some scientists pondered the same question and did a study that was published in Current Biology. National Geographic reviews some of their findings.
Northern gannets, North Atlantic seabirds with a 70-inch (178-centimeter) wingspan, likely use their binocular vision to determine the boat’s speed and fishing activities—and the presence of other birds—before deciding to fly over to investigate.
Once gannets arrive at the boat, they often catch fish that have been thrown overboard, plunge-diving into the water at speeds of up to 60 miles (96 kilometers) an hour.
The study—conducted recently off the coast of Ireland—also revealed that the birds don’t investigate boats that are drifting and not actively in use.
This study is the first to look at the “halo of influence” that a boat has over seabirds—and its large area surprised the scientists, who published their paper June 2 in the journal Current Biology.
Photos: National Geographic (top); SoCal Salty (above)