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2 Similar schemes 3 See also 4 References |
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.
Birds are then 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.
Introduction
Birds are either ringed at the nest, or after being trapped in fine
mist nests, Heligoland traps, duck decoys or similar.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.See also
References
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