Birdwatch News Archive

Decades of ringing has enabled us to discover just how long-lived and well-travelled species like Common Tern can be. Photo: Andreas Trepte (commons.wikimedia.org).

Return of the marathon tern

Posted on: 13 Jun 2012

A long-lived Common Tern at Cliffe Pools RSPB has flown an equivalent distance to the Moon and lived past seven Olympic Games since it was ringed.

As the world looked forward to the Seoul Olympics back in July 1987, Roger Kiddie, a science and maths teacher from Gravesend, rowed out to the tern colony at Cliffe Pools with Cliff Sharr, a local villager and well known ornithologist around the north Kent marshes. The men spent the afternoon ringing Common Tern chicks under a relentless attack from the adults. Common Terns defend their nests aggressively, attacking more furiously those they recognise as repeat offenders. The chicks leave the nest almost immediately after hatching, so time was against the men.

Now, as London prepares to receive visitors from across the globe for the 2012 Olympics, RSPB Cliffe Pools is welcoming back this avian athlete of Olympic proportions. The nature reserve is an important home to wintering wildfowl and waders but also a summer breeding ground for migratory birds such as Common Tern.

This sleek seabird has nested on the islands created by the flooding of the old cement works since they closed in 1970. Roger said: “Common Terns spend their winter off the west coast of Africa; indeed, most of their life is spent at sea, so the chances of recapturing a ringed tern is always slight. But in the 1980s ringing still presented the best opportunity for us to learn where these birds migrate to. We now know that Common Terns return each year to the colony where they hatched, and for Cliffe Pools that means an annual round trip of about 10,000 miles.”

The average lifespan of Common Tern is 12 years so they rack-up a lot of sea miles, assisted by the trade winds and their ability to replace worn-out flight feathers twice in a year. In December 2011, a fisherman from Guinea Bissau, on the west coast of Africa, found a tern on his decks with an injured leg. The fisherman attended to the bird and returned it to the ocean in good health, but not before noting the details of a ring on its 'good' leg. From this information, just received by the British Trust for Ornithology (BTO), we know that this tern was one of those chicks ringed by Cliff and Roger 25 years ago.

Roger has since retired, but continues to ring birds for the BTO. In the tern’s lifetime the Olympics have been to Barcelona, Atlanta, Sydney, Athens and Beijing, and with a little more luck it is now wheeling around the Thames Estuary looking down onto the London Olympics. In its own feat of Olympic proportions, this little bird (equal in weight to a tin of sardines and with a wingspan of just one human arm’s length) has flown the same distance as the Earth is from the Moon.

Roger concluded: “This has to be one of the highlights of my 40 years bird ringing experience, it is truly remarkable.”