Bird ringing

It is common to take measurements and examine the conditions of feather moult, subcutaneous fat, age indications and sex during capture for ringing.

The subsequent recapture, recovery, or observation of the bird can provide information on migration, longevity, mortality, population, territoriality, feeding behaviour, and other aspects that are studied by ornithologists.

For instance during the Punic Wars in 218 BC a crow was released by a besieged garrison, which suggests that this was an established practice.

[3][4] Storks injured by hunting arrows (termed as pfeilstorch in German) traceable to African tribes were found in Germany and elsewhere as early as 1822, and constituted some of the earliest definitive evidence of long-distance migration in European birds.

[5] In North America John James Audubon and Ernest Thompson Seton were pioneers although their method of marking birds was different from modern ringing.

To determine if the same birds returned to his farm, Audubon tied silver threads onto the legs of young eastern phoebes in 1805, although the veracity of Audubon's dates and methods has been questioned,[6] while Seton marked snow buntings in Manitoba with ink in 1882.

[8] The first ringing scheme was established in Germany by Johannes Thienemann in 1903 at the Rossitten Bird Observatory on the Baltic Coast of East Prussia.

This was followed by Hungary in 1908, Great Britain in 1909 (by Arthur Landsborough Thomson in Aberdeen and Harry Witherby in England), Yugoslavia[clarification needed] in 1910 and the Scandinavian countries between 1911 and 1914.

[13] 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.

At times in North America, the bands have just a unique number (without an address) that is recorded along with other identifying information on the bird.

Mist nets come in a variety of mesh sizes, heights, lengths, weights, materials, and colours.

While mist nets are capable of capturing a large variety of species, they require supervised training in order to use properly, and they must be checked frequently while they are deployed.

At the other extreme, the smaller species of river and tree kingfishers, todies and certain lories, have such narrow tarsi that a ring placed around the bird's foot may impose danger to blood circulation.

For some gamebirds, such as the Indian peafowl, spurs on the legs interfere with the rings, which thus can cause injury to the birds.

[20] The ability to overcome this problem varies between species, and with some such as the Gang-gang cockatoo, it is known to be too dangerous to attempt banding.

Most waterfowl are leg ringed, but some are marked with a plastic neck collar, which can be read at a greater distance.

[24] Wing tags can be a problem for some smaller raptors like harriers as their conspicuous nature makes them more obvious targets for other more powerful predators like peregrine falcons.

[25] Where detailed information is needed on individual movements, tiny radio transmitters can be fitted on to birds.

Two field receivers (reading distance and direction) are needed to establish the bird's position using triangulation from the ground.

The technique is useful for tracing individuals during landscape-level movements particularly in dense vegetation (such as tropical forests) and for shy or difficult-to-spot species, because birds can be located from a distance without visual confirmation.

They are used by biologists working in the field to identify individual birds without recapture and with a minimum of disturbance to their behaviour.

The use of colour-coded leg-flags is part of an international program, originated in Australia in 1990, by the countries of the East Asian - Australasian Flyway to identify important areas and routes used by migratory waders.

They should not be used on birds that live in icy climates, as accumulation of ice on a nasal saddle can plug the nostrils.