Gannets risk lives for break-neck dives
GANNETS ACTUALLY HURT THEMSELVES, sometimes fatally, when they dive at break-neck speeds into the sea and fight other birds for a good feed.
That’s the conclusion of New Zealand’s Massey University researcher Gabriel Machovsky Capuska after filming the Australasian gannet, Morus serrator, on location around New Zealand.
The sleek yellow-throated seabirds with blue-rimmed eyes found in 29 colonies around the country repeatedly dive 15 metres to hit the water in less than a second, reaching about 20m below the surface in pursuit of prey.
Gannet diving a risky move
Footage of underwater collisions reveals the risks the birds take, particularly when they try to pinch a fish from the beak of another gannet under the surface of the water.
They can die of fatal neck and head injuries from accidental collisions, Gabriel, an Argentinian scientist based in New Zealand, says.
Post-mortem examinations of two of 50 carcasses collected from Hauraki Gulf waters showed the gannets had died from collision injuries.
The search for food can also be a marathon effort.
Gannets use “extraordinary vision”
At Cape Kidnappers, where 10,000 breeding pairs dwell, the average gannet can fly up to 500km at an average 70km/h in a day to seek out shoals of small pilchards and anchovies.
When they find them they must then compete with other foraging seabirds as well as dolphins, whales and sharks.
“Equipped with extraordinary vision, they can adapt their optical capability in a split second from air to water while effectively blocking out ultraviolet light reflection that distorts the position of darting prey,” Gabriel says.