Species of the week: The Arctic tern

As summer comes to a close, the idea of flying off to distant lands before the chill sets in probably appeals to many of us. Of course, for many species of birds, this dream is a regular reality, as they migrate to either exploit the benefits or to escape from the dangers of living in a seasonal environment. 

While some birds only migrate locally in response to extreme weather conditions, others undertake seasonal long-distance migration between land masses and sometimes hemispheres. 

The most impressive avian migrator is, by far, the Arctic tern (Sterna paradisaea). Weighing an average of 100g, with a wingspan of 75-85cm, the birds sometimes nest just once every three years, as so much of their 30 year life span is spent in flight. The bird has the longest seasonal movement than any other animal, and move so consistently with the seasons that they only ever see long days; they experience more sunlight per year than any other creature.

Image courtesy of LindsayRs

The Arctic tern begins its 70,000km round trip in the Northern hemisphere. Several tagged birds (migrating from Iceland or Greenland) have been seen to make a key ‘fuel stop’ in the North Atlantic Ocean, before continuing on their epic journey south to their wintering grounds. Here, they take advantage of the seasonal high marine productivity by feeding on small fish and zooplankton. Strangely, these birds did not follow their same flight path home again, but made a detour of several thousand kilometres by instead flying in a northbound ‘S’ route. It is thought that this pathway takes advantage of the prevailing wind system; while following this flight path racks up more air miles than retracing the original, it is more energy efficient.

The Arctic tern features in the Society of Biology’s ‘Animal Olympians’ activity, which will be showcased, along with a collection of other biological displays and experiments, as part of the Society’s interactive stand at BBC Bang Goes The Theory LIVE this weekend in Cwmbran, Wales and next weekend in Bradford, England.

Sources used: http://goo.gl/Yl5nf, http://goo.gl/aZ8ry, http://goo.gl/y3beb and http://goo.gl/37BVx