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Introduction and General Information

It is important to be able to identify animals correctly at the species (and subspecies if relevant) and individual level.

Reasons to identify species:

  • Correct identification of species is important for all types of management or groups and individuals, both captive and free-living, including handling, housing, feeding, breeding, veterinary care and disease investigation/prevention/management.
  • Accurate identification of species is important in breeding programmes to avoid hybridisation, and in consideration (important for release purposes) of whether an individual bird casualty is a native species, a feral introduced species or an exotic escapee from a collection.
  • The occurrence and appearance of disease may vary widely across apparently similar species, making species identification vital in disease investigation and management, while species differences in response to drugs (e.g. anaesthetic dosages required) must also be considered.

Reasons to identify individuals/groups of individuals:

  • Proof of ownership
  • Theft deterrent
  • Insurance claims
  • General and veterinary management
  • Record keeping for general management, veterinary management, breeding/genetics
  • Seller/purchaser agreements/disputes
  • Certification of origin of transported animals
  • Behavioural studies
  • Group disease and movement/dispersal investigations

The ideal means of individual identification should be:

  • Safe for the animal, not affecting either behaviour or survival
  • Stress- and pain-free in application
  • Secure and tamper-proof
  • Last for the appropriate length of time
  • Positively and uniquely identify the marked individual,
  • Easily read/observed at a distance
  • Allow appropriate record-keeping
  • Easy to use
  • Readily available at a reasonable price

N.B.

  • All forms of identification require good record keeping in order to be maximally useful.
  • No single method of identification is ideal for all species and individuals and in all circumstances.
  • A combination of two or more identification methods is useful in most practical circumstances, for example coloured leg bands (easily visible) in combination with implanted transponders (unique).

(B22.5.w2, B36.6.w6, B130.3.w1, P4.1994.w3)

Waterfowl Consideration
  • Even within a taxonomic group such as waterfowl, considerable differences exist in behavioural (e.g. communal or solitary), housing (e.g. requirements for deep water, or protection in cold weather) and feeding requirements (e.g. grazer, dabbler or fish-eater), both short term (for example a bird being rehabilitated) and long term (for example a bird in a captive breeding programme). Correct identification as to species (and recognition of the varying requirements between groups) is therefore very important.
  • As with other species, reliable identification of individuals is important for general, genetic and veterinary management.
  • Individual identification of waterfowl during rehabilitation (particularly e.g. in oil-spill situations, where large numbers of birds may be involved) is essential for ensuring that all birds are treated (including e.g. fluid therapy and tube feeding) and for monitoring regarding factors such as weight gain during treatment and survival post release.

(V.w5)

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Identification of Species

  • Species identification is generally based at least initially on basic phenotypic characteristics such as size, shape and colouration. Related species frequently have common characteristics allowing convenient groupings on various levels from kingdom to genus.
  • In some taxonomic groups, accurate species identification may require careful examination of a combination of characteristic features.

(V.w5).

Waterfowl Consideration
  • Within waterfowl there are a number of commonly-accepted groupings (e.g. swans, pochards, sheldgeese) based on genetic relatedness and behavioural considerations; a small number of species do not fit easily into any of these groupings.
  • Waterfowl species are usually distinguished from one another by details of the plumage, eyes, bill and legs. Species identification of downy youngsters, immature birds, female ducks of sexually dimorphic species and male ducks in eclipse plumage may be more difficult.

(B13.46.w1, B25, V.w5)

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External Markings

Natural Markings:
  • Individual characteristics commonly used for identification of individual animals include natural variations in e.g. coat or plumage colour and pattern, as well as clearly visible acquired marks such as scars, and other unique features.
  • These are safe for the animal (require no interference), unique, secure, usually non-wearing and tamper-proof, and may positively and uniquely identify individual animals. Their use also requires minimal cost (e.g. photographically recording the pattern/markings, producing and updating records).
  • Recognition of individual animals by their individual characteristics is commonly used for daily care and management of animals in collections, and for behavioural studies on captive or free-living animals.
  • N.B.
  • Individual characteristics are not equally useable for all species/individuals.
  • Small, ill-defined variations are difficult to use in practical terms for large groups of animals.
  • Mis-identification may occur particularly when groups of animals are transported to different collections, unless markings are easily recordable and unmistakable.
  • Changes may also occur with time, and this may cause mistakes in identification, particularly between similar individuals and/or when an observer or individual animal has been absent for a period.
  • As with all identification methods, permanent records accurately showing the relevant identifiers must be kept to minimize the potential for confusion.

Dyes, Sprays and Paints:

  • Dyes, sprays and paints may be useful when temporary marking of individuals or groups is required, for example rapid identification of an individual undergoing treatment or monitoring, or study of dispersal of groups of wild birds following a disease management operation.
  • Paints or dyes used for marking birds should be non-toxic and rapidly-drying.
  • Care must be taken to hold painted feathers apart while dye or paint is drying, to ensure feathers do not stick to one another and impede flight.

Tattoos:

  • Tattoos are produced by injecting ink into the skin using an electric tattoo pencil or a tattoo pliers, usually forming a series of numbers and/or letters
  • Tattoos provide a permanent mark on the individual, are cheap to apply and any combination of letters/numbers may be used.
  • There is the possibility of infection on application of the tattoo.
  • Tattoos are often difficult to read without catching the animal and may become blurred or faded with time.
  • Tattoos may easily be copied to falsely certify a second individual.
  • Tattoos are of limited use in birds, which have thin skin and little tissue into which a tattoo can be placed, so that numbers/letters do not remain legible.
  • They have been used in birds for identifying the sex of individual birds, as a simple blob injected sub-epidermally into the ventral wing web, of the left wing in confirmed females, right wing of confirmed males.

Toe web punching:

  • This has been used in web-footed birds.
  • A code must be developed.
  • Cuts and tears in the foot webs can change the pattern, with the identification being lost. 

(B13.1.w18, B36. 6.w6, B130.3.w1, J23.8.w3, P4.1194.w3).

Waterfowl Consideration
  • Individual birds may often be reliably recognized by experienced keepers or observers.
  • Bill patterns have been recorded and used to recognize hundreds of individual Bewick's swans Cygnus columbianus bewickii. Both pictorial records and descriptions analysing particular features of the bill pattern are used. It is recognized that there may be changes in bill pattern of individuals over time; other factors such as known associations between birds (e.g. pairs, families) may be used to confirm identity in such cases. Observers familiar with the swans will tend also to use other, unquantified features in identifying individuals (J7.17.w3, J7.28.w2, J7.28.w3).
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Rings, Bands & Tags

GENERAL:
  • A wide variety of leg rings, neck bands and patagial (wing) tags have been used to identify birds. Leg bands are used most commonly and vary from small metal bands stamped with combinations of letters and/or numbers to plastic bands which may be used in various colour combinations to indicate identity and large bands made from polyvinyl chloride (PVC) and engraved with large numbers/letters (e.g. Darvic bands). It is conventional in aviculture to place rings on the left leg of females, right leg of males, if the sex of the bird is known at the time of ringing.
  • In Britain and Ireland, ringing of wild birds is organized by the British Trust for Ornithology (British and Irish Ringing Scheme), which trains and licences bird ringers and records and analyses information from ring recoveries (see: P12 - Organizational Overviews: Role of the British Trust for Ornithology). Rings used in the Scheme bear a unique identifying code. They are carefully chosen to fit the species the rings are used on and (in the case of open rings) are applied to the bird using special ringing pliers (D7).
  • [ N.B. The British Trust for Ornithology encourages anyone finding a bird (live or dead) which bears an identifying ring to report the finding to them. Live birds should not be trapped or caught to read a ring, but ring numbers of birds at a bird table, for example, may be read e.g. through a telescope. The following information is requested (N3):
  • "THE RING - Write down the ring number and, if the bird is dead, please enclose the ring taped to your letter. The ring will be returned to you if you wish to keep it. If it is not a BTO ring, (address starting BTO or British Museum), please give the address as well.
  • WHERE - Give the location the bird was found including the name of the nearest town or village and a grid reference if possible.
  • WHEN - Give the date the ringed bird was found.
  • THE CIRCUMSTANCES - Say if the bird was alive or dead. If dead, please give the cause of death if known, e.g. was it hit by a car, brought in by a cat, or found oiled on a beach? Also note if the bird was freshly dead or decomposed etc. If the bird is alive please say what happened to it.
  • THE BIRD - Write down the type of species of bird, if you know.
  • YOUR DETAILS - Don't forget to give your name and address so that you can be sent the information about when and where the bird had been ringed. Details will normally be sent within a month but there may be delays at busy times of year. If you send a report of a ringed bird by E-mail, please include your postal address.
  • Please remember, if you see a healthy wild bird wearing a ring, feeding on your bird table for example, you must not try to catch it. In these situations you may be able to read the ring number through a telescope."

This information may be sent to: The Ringing Unit, BTO, The Nunnery, Thetford, Norfolk IP24 2PU Tel: 01842 750050 Fax: 01842 750030 Email: ringing@bto.org (N3).

  • All leg rings have the potential for causing damage to the bird wearing the ring, for example by becoming caught in wire or vegetation, or if the leg of the bird becomes swollen for any reason, including due to build-up of leg scales. Bands which are too small also may cause constriction as the bird grows, while bands which are too large may settle over toes or joints and may be more likely to get caught up on external objects. The potential for injury is minimized by ensuring that the correct size of ring is used.
  • Observation of birds ringed as part of the British and Irish Ringing Scheme (British Trust for Ornithology) indicates that the rings used in the Scheme do not unduly affect the birds they are used on (D11).
  • Coloured bands must be used with caution as band colour has been shown to affect mate choice and survival in some species of birds (B105.15.w2).
  • N.B. Strong metal bands may require the use of special cutters or a drill for safe removal (See: Leg-Ring Removal for Birds).

Metal leg rings / bands:

  • Lightweight metal leg rings, carrying identifying alphanumeric codes, have been used for many years to identify both captive and free-living birds.
  • Closed rings must be applied at an early age, while open rings may be attached to older birds.
  • It is important to use only one metal band on one leg, as two such bands may damage each other and may cause injury to the bird (B130.3.w1).
  • Butt-ended metal rings may be removed by the larger psittacine birds and by vultures.

Closed rings:

  • These are a special type of metal ring, which must be placed on the bird while the bird's foot is small enough to fit through the ring. This may be difficult, particularly with parent-reared birds in large areas and they are, of necessity, useful only in birds which can be handled at the correct age.
  • Closed rings bear a unique identifying code and may be used as a recognized legal means of identifying an individual, as the ring cannot be removed without damaging the ring and/or the bird.
  • These rings cannot be replaced if removal becomes necessary for any reason. Close-ringing may be required legally to certify bird identity and status (e.g. captive bred).

Plastic flat rings:

  • Rings made from a flat strip of plastic which wraps around the leg and overlaps itself are available in a variety of sizes and colours.
  • Cheap and lightweight these are readily available in a wide variety of sizes and colours.
  • Plastic rings may become brittle with time, be more easily broken and lost than metal rings, and the colours may fade with time.
  • Loss of a ring or colour changes (e.g. fading of red to orange) may lead to confusion in identification.
  • They are not useful on psittacines which may easily break and swallow the plastic.
  • Cranes may be adept at removing these bands.
  • They may be particularly useful for temporary identification e.g. of downies.
  • They may be used in combination with more permanent identifiers (e.g. metal leg rings or microchips / transponder) as a means of identifying individuals at a distance.
  • They are not suitable as a permanent, legal means of identification, as they are easily removed and re-placed on other birds.

Plastic spiral rings:

  • Rings made from a spiral of plastic.
  • Cheap and lightweight these are readily available in a wide variety of sizes and colours.
  • They may become brittle with time, be more easily broken and lost than metal rings, and the colours may fade with time.
  • In some cases the end of the spiral may dig into the leg of the bird and cause lameness and physical injury.

Cable ties:

  • Thin, tough, coloured or colourless plastic, with an adjustable ratchet lock.
  • Once in place these cannot be opened without being cut.
  • They may be trimmed and heat-sealed once in place.
  • Cable ties may be used as leg bands or as flipper bands (see below) for penguins.

Neck Bands:

  • Large tough plastic bands placed on the neck of long-necked birds.
  • Large letters/numbers are present in a contrasting colour and may be read easily at a distance.
  • They may be used where rapid identification of individuals at a distance, is required, e.g. for behavioural studies.
  • They need to be specially prepared prior to use.
  • As with leg rings, they may cause injury if they catch on e.g. vegetation.
  • The colour may be subject to some fading with time.

Patagial Tag (Wing Tag):

  • Coloured and/or numbered/lettered tags, placed on the wing over the secondary coverts and held in place by a metal band piercing through the patagium.
  • These are inexpensive, easy to use and readily available.
  • They may be used for identification of individuals at a distance.
  • They may interfere with behaviour, breeding and survival, at least in some species (J48.69.w1).
  • The site of attachment may become infected.
  • The tag may be lost and numbers may wear away.

Flipper Band:

  • These are used for the identification of penguins.
  • They may be made from e.g. metal or plastic.
  • Care must be taken to ensure they do not become too tight.

(J48.69.w1, B13.1.w18, B22.5.w2, B130.3.w1, P4.1994.w3, V.w5)

Waterfowl Consideration
  • Leg bands of various types are commonly used in waterfowl. Large coloured bands with letters/numbers in contrasting colours are used for identification at a distance. Un-marked coloured leg bands may be used in various colour combinations to denote individuals. Closed rings may be used to permanently identify waterfowl, for example for the identification of captive-bred British species.
  • Suggested average closed ring sizes for all waterfowl species, and information on and details of closed and split rings are included in the "Aviornis UK Ringing Scheme" (D8)
  • Neck Bands have been used for studies of geese and swans. There is some evidence that survival rates of wild waterfowl wearing neck bands may be reduced (J40.60.w1).
  • Patagial (wing) tags may have negative effects on the behaviour and breeding ability of diving ducks such as Oxyura jamaicensis - Ruddy duck (J48.69.w1).

(J40.60.w1, J48.69.w1, B130.3.w1, D8)

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Electronic Identification

Microchips or transponders are potentially permanent, unique identifiers which may be used in most animal species. Each transponder consists of a small cylinder of glass (may be e.g. 1mm x 4mm), coated with special inert coating and containing a microchip with a unique electronic identifying number.
  • Microchips / transponders are implanted by injection, subcutaneously or intramuscularly, depending on the species the microchip is implanted in.
  • Guidelines have been developed for the sites at which Microchips / transponders should be implanted in different species. In birds, Microchips / transponders are usually implanted into the pectoral (breast) muscles or thigh muscles. They can often be implanted without the use of anaesthetic agents, although a brief anaesthetic may be preferable for implantation in some species/individuals.
  • N.B. Microchips / transponders need a a special instrument to be placed in the animal, and a special scanner in order to be detected and read. Scanners need to be within a few centimetres of the chip in order for the chip to be read, therefore microchips are only useful for identification at close range. Different systems exist and their scanners cannot read each other's transponders. Readers capable of detecting multiple makes of transponder are being developed; one already in existence is not yet universally reliable in detecting all transponders.
  • Microchips / transponders are not infallible: they may break when inserted or at a later time. They must be checked immediately after insertion and should be checked periodically thereafter (e.g. when birds are caught for management or veterinary purposes).
  • Size constraints prevent the use of microchips in very small individuals.
  • Microchips are relatively expensive.
  • Microchips / transponders are ideal for entering into computerized record-keeping systems, such as ISIS (International Species Information System).
  • Microchips / transponders may be used in conjunction with more visible but less permanent markers such as tags or bands for daily identification of individuals.
  • Microchipping may act as a deterrent to theft, as a transponder can be used to positively identify a recovered bird.
  • Microchips / transponders are visible radiographically.
  • Microchips / transponders are recommended as a global standard for permanent identification of individual animals, by the Captive Breeding Group of the World Conservation Union's Species Survival Commission (B22.5.w2).

(B13.1.w18, B22.5.w2, P4.1994.w3)

Waterfowl Consideration Microchips / transponders may be used in waterfowl.
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DNA "Fingerprinting"

DNA "fingerprinting" may be used for identification at both the species and the individual level.
  • Record made from blood taken and sent to a specialist laboratory.
  • This technique allows accurate identification of an individual.
  • It is a relatively expensive undertaking.
  • Being a unique identifier, this method may be used as positive proof of identity, if DNA fingerprints of a disputed individual match a DNA record are already held.
  • Samples taken from a group of individuals may be used to establish information on genetic relationships, such as confirming (or disproving) putative parents. This has been used successfully in legal prosecution to show that putative captive bred birds could not have the parentage ascribed to them.
  • N.B. Identification of a recovered stolen/lost individual by DNA "fingerprinting" is possible only if a DNA sample had been taken from the individual previously.
  • DNA "fingerprinting" may be used to confirm whether individuals are pure-bred or hybrids. This may then be used to ensure breeding programmes include the appropriate individuals, and to remove hybrids from such programmes. DNA "fingerprinting" has been used in this way for e.g. rare pheasants.

(B13.1.w18, P4.1994.w3, N2.79.w1)

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Authors & Referees

Authors Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee  

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