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2 Similar schemes 3 Some results 4 See also 5 References |
Birds are either ringed at the nest, or after being trapped in fine
mist nests, Heligoland traps, duck decoys or similar.
A ring of suitable size is attached, and has on it a unique number, plus
a contact address. The bird is often weighed and measured, and examined
for parasites (which may then be removed) before release. The rings are very light-weight, and have no adverse affect on the birds. The individual birds can then be identified when they are re-trapped, or found dead.
The finder can contact the address on the ring, give the unique number,
and be told the known history of the bird's movements.
The organising body, by collating many such reports, can then determine
patterns of bird movements for large populations.
The first orgainsed schemes for bird ringing were started by Arthur Landsborough Thomson in Aberdeen and Harry Witherby (in 1909 in England, though smaller individual marking tests had began some years earlier in Denmark and Germany.
A Manx Shearwater ringed as an adult (at least 5 years old), breeding on Copeland Island, Northern Ireland, is currently (2003/2004) the oldest known wild bird in the world: ringed in July 1953, it was retrapped in July 2003, at least 55 years old. Other ringing recoveries have shown that Manx Shearwaters migrate over 10,000 km to waters off southern Brazil and Argentina in winter, so this bird has covered a minimum of 1,000,000 km on migration alone (not counting day-to-day fishing trips). Another bird nearly as old, breeding on Bardsey Island off Wales was calculated by ornithologist Chris Mead to have flown over 8 million km (5 million miles) during its life (and this bird is still alive in 2003, having outlived Chris Mead).
Introduction
Similar schemes
Wing tags
In some surveys, involving larger birds such as eagles, brightly-
coloured plastic tags are attached to birds' wing feathers. each has a
letter or letters, and the combination of colour and letters uniquely
identifies the bird. These can then be read in the field, through
binoculars, meaning that there is no need to re-trap the birds. Because
the tags are attached to feathers, they drop off when the bird
moults.Radio transmitters
Scientist are now running schemes where minute radio transmitters are
attached to the feathers of large migratory birds (geese
and swans are popular subjects). These are then tracked by satellites.
As with wing tags, the transmitters are designed to drop off when the
bird moults.Some results
An Arctic Tern ringed as a chick not yet able to fly, on the Farne Islands off the Northumberland coast in eastern Britain in summer 1982, reached Melbourne, Australia in October 1982, a sea journey of over 22,000 km (14,000 miles) in just three months from fledging.
Copeland, ringed 1953
Copeland Bird Observatory
BBC News
Bardsey Island, ringed 1957
Bardsey Island Bird Observatory
BBC News
Wildlife Britain newsSee also
References
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