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Atlantic Seabird: Young and Old Foragers in Separate Units

Nov 30, 2015 01:12 PM EST
Manx shearwater
Very long-lived seabirds, the Manx shearwater, were recently studied by the University of Oxford.
(Photo : Annette Fayet)

A recent study looked at the manx shearwater (puffinus puffinus), a common seabird off the United Kingdom's west coast that is also seen more and more off North America's Northeast coast. Typically measuring about a foot long and having long straight narrow wings, black above and white below, shearwaters look like crosses when they fly. They sometimes live to 55 years old or more, and have been known to dive deep into waves to seek the same fish as dolphins. Manx shearwaters migrate to the coast of South America after July, returning north in late February and March.

Numbering at about 340,000-410,000 pairs worldwide, according to the 2004 survey Seabird Populations of Britain and Ireland, the birds have conservation priority status with the European Union. 

The recent study by University of Oxford looked at immature (non-breeding) and breeding manx shearwaters, to learn whether they show differences in foraging at sea and are segregated while doing so.

"We know very little in general about what immature seabirds do while they're at sea, so there is lots of scope for research and for learning more about their behaviour. The Manx shearwater is no exception to this --- and, indeed, they are particularly interesting because they can live for more than 50 years and don't start breeding until they are around five years old," said fourth-year PhD student in zoology Annette Fayet in a release.

The researcher found that the immature and breeding birds foraged separately and the young birds gained less weight, which indicated that they found less of it. The findings were recently published in the journal Animal Behavior.
In the study, the scientists attached small GPS trackers on both types of birds from the Manx shearwater colony off the island of Skomer, along the Pembrokeshire (Welsh) coast.

Tracking the birds' foraging for its usual duration of up to 15 days, the scientists learned when the birds were flying, sitting in water, or foraging. The study is one of the first to keep track of immature birds at sea, noted the release.

Young birds may just need a few years to become better foragers, said Fayet in the release. "Research like this is...has important applications for the conservation of these species by identifying important foraging areas, which can help inform future decisions on conservation. These young birds are the next generation of breeders, and we need to learn as much as we can if we want to protect them."

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-Follow Catherine on Twitter @TreesWhales

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