American Birding Podcast



Arctic Terns Taking the Long Way

via DC Birding Blog

ARTE wiki

The epic planet-spanning migration of Arctic Terns is among the most famous of all bird species. Wile they seemed to lose the title of “longest migratory route” to the Sooty Shearwater – whose 40,000 mile trek around the Pacific was documented in 2006 – for a time, a recent study looks to hand that title back to the bird that for many is the textbook example of avian endurance.

We’ve known for a very long time that Arctic Terns breed in the high latitudes of the Arctic in the northern hemisphere summer before traveling to the other pole to spent the southern hemisphere summer foraging in the productive waters around Antarctica, but a team of researchers tagging breeding Arctic Terns with geolocators (what else, after all?) in the Netherlands has shown in the journal Ardea, that there’s much more to that oversimplified route.

The tracked terns spent on average 273 ± 7 days away from The Netherlands, and visited known staging areas in the North Atlantic  and the Benguela Current, on both the outward and return journey. Similar tracks were observed in the terns from Greenland.

However, hereafter the terns from The Netherlands moved to a previously unknown staging area in the central Indian Ocean, between 20–40°N and 65–100°E, and spent most of the non-breeding season in the Southern Ocean between 35–150°E. One bird migrated as far as New Zealand.

Eventually, all five birds spent the Austral summer in Wilkes Land, Antarctica, before flying back to the breeding colonies with a small detour to the same North Atlantic staging area they visited on their southward migration. The total travel distance in the course of the non-breeding period was ~90,000 ± 2000 km, which substantially exceeds previous estimates for this species.

For the non-metric among us, 90,000 km is on the order of 56,000 miles. Truly remarkable.

The full study, including a remarkable map showing the journey of these geolocated birds, is available online here.