Nearly two million seabirds nest along the Norwegian coast north of the Arctic Circle. How do they decide where to nest?
Date: May 13, 2016
Source: Norwegian University of Science and Technology
Seabirds nest by the hundreds of thousands in colonies along the Norwegian coast. By combining an ocean current model with fish larvae transport modeling and bird population numbers, researchers have uncovered the factors that help determine the location of seabird nesting colonies.
Ninety per cent of Norway's two million pairs of cliff-nesting seabirds are located in nesting colonies above the Arctic Circle.
But why are these colonies located exactly where they are? Much of the 1200-km stretch of coastline from the Arctic Circle to Norway's easternmost point, on the Russian border, has features that ought to be attractive to birds that nest in colonies, mainly steep, protected cliffs that are essentially inaccessible to terrestrial predators.
Using computer models to describe ocean currents and the transport of floating fish larvae, researchers were able to show that bird colonies are located in areas where currents and the shape of the coastline cause fish larvae to concentrate.
More simply stated, "the birds are where the food is," said Hanno Sandvik, a biologist from the Centre for Biodiversity Dynamics at the Norwegian University of Science and Technology (NTNU) and first author of a paper published inNature Communications on Friday.
This may seem like a self-evident fact, but the research team is the first ever to be able to essentially predict where seabird colonies should be, based on fish larvae "hot spots" that show up in computer models of how fish larvae are transported along the coast.
"We are starting from where the prey is," Sandvik said. "We know where the prey is (because of the computer models). Then, based on what we know about where their prey is, where should the colonies be?"
Spotting a pattern in hot spots
The idea for the study came about several years ago, when researchers met to discuss a different project for which oceanographers from the Norwegian Institute of Marine Research (IMR) had created a coastal current and fish larvae transport model.