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BearsClick here for full page view with caption Click here for full-page view with caption Click here for full page view with caption Click here for full-page view with caption Click here for full-page view with caption Click here for full-page view with caption Click here for full-page view with caption Click here for full-page view with caption Click here for full-page view with caption RabbitsColoured wax on the ears to identify individual pygmy rabbits. Click here for full page view with caption. Pygmy rabbit ready for release, with radiocollar. Click here for full page view with caption. Pygmy rabbit ready for release, with radiocollar. Click here for full page view with caption. Radiotracking pygmy rabbits in Idaho. Click here for full page view with caption. Sylvilagus backmani with ear tag. Click here for full page view with caption Breeders leg ring. Click here for full page view with caption Removing breeders leg ring. Click here for full page view with caption TranspondersMicrochips. Click here for full-page view with caption Microchip implanter. Click here for full-page view with caption Microchips. Click here for full-page view with caption Microchip reader. Click here for full-page view with caption Trovan reader and chip. Click here for full-page view with caption

Introduction and General Information

It is important to be able to identify animals correctly at both the species (and subspecies if relevant) and individual animal level.
Reasons to identify species
  • Correct identification of species is important for all types of management of 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 wildlife casualty undergoing rehabilitation is a native species, a feral introduced species or an exotic animal escaped from a collection.
  • Identification of subspecies as well as species should be made and recorded, including the location of origin of the individual (or for captive-bred animals, the founder individuals), to allow for changing taxonomic information, such as new recognition of a subspecies or species.
  • 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
There are a variety of reasons why identification of individuals or groups of individuals is wanted or required, including:
  • General and veterinary management.
  • Record keeping for general management, veterinary management and breeding/genetics.
    • Individual identification of wildlife casualties during rehabilitation is essential for ensuring that all individuals are treated, for monitoring the progress of each individual, for ensuring that treatments and progress are properly recorded, and for cross-referencing with post-release survival (See: Wildlife Casualty Record Keeping).
    • Individual identification of animals of rare species is essential for breeding management and avoidance of inbreeding. (B512.w12)
  • Certification of origin of transported animals.
  • Behavioural studies, both in the wild and in captive animals.
  • Group disease and movement/dispersal investigations.
  • Post-release monitoring of rehabilitated animals (see: Post-Release Monitoring of Oiled Wildlife).
  • Proof of ownership.
  • Theft deterrent.
  • Insurance claims.
  • Seller/purchaser agreements/disputes.
Identification methods

The ideal means of individual identification should be:

  • Safe for the animal, not affecting its behaviour, health or survival.
  • Stress- and pain-free during and following application (as much as possible).
  • Secure and tamper-proof.
  • Last for the appropriate length of time (in a zoological collection, permanent). (B429.5.w5).
  • Positively and uniquely identify the marked individual.
  • Easily read/observed at a distance.
  • Allow appropriate record-keeping.
  • Easy to use and quick to apply, to minimise stress on the animal during application (B429.5.w5)
  • Readily available at a reasonable price.
    • Inexpensive for use in zoological collections. (B429.5.w5)
  • For use in zoos, inconspicuous to the public, not detracting from the animal's appearance. (B429.5.w5)

(B22.5.w2, B429.5.w5, B438.24.w24, J232.44.w1)

Additional considerations
  • 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 ear tags (easily visible) in combination with implanted transponders (unique).
  • While newborn animals in a collection should be marked for identification as soon as possible, it is important to consider the effects on the infant and the maternal-infant bond. 
    • Ungulates may be caught, health checked and given an identifying mark at 24 - 48 hours, giving time for the maternal bond to develop, but while the calf is still easily caught. (B429.5.w5)
    • It is recommended that primates are not caught and marked until they are old enough that they are spending some time moving around independent from their mother. (B429.5.w5)
  • To minimise the risk of infection, when using any method in which the skin is broken, excess hair should be clipped and the site should be cleaned properly with alcohol before the mark is applied. Additionally, marking tools should be disinfected before each use. (B429.5.w5)
  • To avoid catching animals simply to mark them, identifying marks may be applied when an individual is restrained for another purpose (e.g. health check, movement).
  • The ability to identify individuals is useful only in combination with good record keeping systems indicating parentage, movements of individuals between collections, etc.

(B22.5.w2, B36.6.w6, B130.3.w1, B429.5.w5, B438.24.w24, B512.w12, D15, J23.8.w3, J23.8.w4, J23.8.w5, J23.8.w6, J23.8.w7, J23.8.w8 P4.1994.w3, P1.1976.w3)

Bear Considerations

As with other mammals, bears should be identified to species (and subspecies, if relevant), and as individuals.
  • Even within a taxonomic group such as bears, considerable differences exist in behavioural (e.g. tree climbing, swimming), housing (e.g. requirement for protection in cold weather) and feeding requirements, both short term (for example an individual being rehabilitated) and long term (for example a bear in a captive breeding programme). Correct identification as to species, and recognition of the varying requirements between species, is therefore very important.
    • There are recognised subspecies within several of the bear species. In particular, there are a number of subspecies of Ursus arctos - Brown bear.
  • Bears should be individually marked to allow unambiguous confirmation of individual bear identity. (D247.7.w7)
  • As with other species, reliable identification of individuals is important for general, genetic and veterinary management, including management of individuals during rehabilitation.
  • More than one method of identification may be used on an individual bear. (J332.86.w1)
  • Captive bears should be marked at an early age when they are easy to restrain, for example when they are first restrained for sex determination and de-worming. (D247.7.w7)

(D247.7.w7, J332.86.w1, V.w5)

Lagomorph Consideration
Species Identification

Accurate identification of species is very important in wildlife rehabilitation, particularly for example in North America, accurate distinction between wild-colour domestic rabbits (Oryctolagus cuniculus - European rabbit) and native cottontail rabbits.

  • Accurate identification of species is particularly important for hand-rearing, because different lagomorphs are born at different developmental stages and therefore have different hand-rearing requirements. It is particularly important to be able to distinguish between Lepus spp., which are highly precocial at birth, and rabbit species. Improper identification may lead to a newborn leveret (fully furred) being treated as a rabbit kit of several weeks of age. 
Individual animal identification
  • Identification of individual lagomorphs in a colony, multi-rabbit household, or in a litter being hand-reared is ensures that proper records can be kept of each animal.
  • Accurate identification of each individual while in veterinary care is very important. This may include e.g. a written description and/or a label on the cage. (B545.8.w8)
  • Where maintenance of individual identification in a group of lagomorphs is essential, two methods of identification should be used simultaneously. (J83.27.w1)
Ferret Consideration Distinguishing between polecat-marked Mustela putorius furo - Ferrets and their wild progenitors (probably) Mustela putorius - Polecats is difficult. (B656)

As with all animals, it is very important to ensure accurate identification of each individual ferret while in veterinary care, to ensure correct treatment. (V.w5)

Bonobo Consideration

Bonobos were recognised as a separate species from Pan troglodytes - Chimpanzee relatively recently. The small number of  in human care are all recognised by their individual characteristics. Studies in the wild also make use of individual apperance for identification.

  • Unambiguous identification of individual primates is fundamental for record keeping and for breeding. (B671.12.w12)

Published Guidelines linked in Wildpro

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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 generally 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.
  • The use of a taxonomic key allows differentiation on the basis of one characteristic at a time on an elimination basis.
  • Individuals who are familiar with a given taxonomic group often distinguish between species on the basis of the overall appearance of the animal, but might not easily be able to define the differences they are using to make distinctions.
  • Anatomical features such as skeletal and dental characteristics may be required to confirm distinctions between species or subspecies. It is necessary to know which features are species-specific, and which may change in association with e.g. diet.


Bear Considerations

There are a number of characteristics which can be used to distinguish between the different bear species.
  • Ursus maritimus - Polar bear has a relatively small head and long neck, no muscular hump on the shoulders, white fur, and the combined length of the first and second molars is less than the width of the palate. The soles of the feet are hairy. (D244, B147, B180.w4, B288.w11, B285.w4)
  • Ursus arctos - Brown bear has a prominent muscular hump on the shoulders and a dished facial profile. The claws of the front feet are particularly long, about twice the length of those on the hind feet. These bears lack any pale marking on the chest or around the eyes. The outer pair of incisors are larger than the two inner pairs. The width of the palate between the first and second molars is less than the combined length of these two molars. The first mandibular molar has a length always >20.4 mm and a width >10.5 mm, while the second maxillary molar always has a crown length >31 mm. (B180.w3, B421.w1, D243)
  • Ursus americanus - American black bear has a straight facial profile, no or only a slight muscular hump on the shoulders, claws on the front and hind feet are about the same length, and the three pairs of upper incisors are of approximately equal size. The chin is black, and this species only infrequently has any white mark on the chest. It does not have longer hairs fringing the neck and shoulders. (D245)
  • Ursus thibetanus - Asiatic black bear is usually black with a tan or brown muzzle (rarely reaching past the eyes, unlike Helarctos malayanus - Sun bear), white or buff chin and a characteristic white, yellow or buff coloured "V" on the chest. It does not have a shoulder hump (unlike Ursus arctos - Brown bear), is more compact in build than Melursus ursinus - Sloth bear and the claws are curved and black. The fur in general is longer than that of Helarctos malayanus - Sun bear but shorter than that of Melursus ursinus - Sloth bear; there are long hairs on the ears and fringing the cheeks and down the sides of the neck and shoulders, forming a ruff. (B288.w11, B392.8.w8, B424, B425)
  • Melursus ursinus - Sloth bear is distinguished from other bears by its long, heavy, shaggy coat and rolling gait. The coat is black, often with a brownish tinge (occasionally it is brown). On the breast is a whitish, V-shaped, patch. The tips of the feet are yellowish or dirty white and the hooked claws are ivory white. The lips are pronounced (the lower lip can be stretched over the outer edge of the nose) and the tongue is long and flat, the front upper incisors are absent and the palate is broad and deeply concave. (B144, B285.w4, B288.w11, B392.8.w8)
  • Helarctos malayanus - Sun bear is the smallest of the bears, stocky, with a short, flexible muzzle and a long slender tongue. The forelimbs are more bowed than those of other bears, the large feet turn inward, the claws are pointed and strongly curved (sickle shaped) and the soles are hairless. The ears differ from those of Ursus americanus in being shorter, narrower and simpler. The fur is short, black to dark brown, with a horseshoe-shaped marking on the chest, whitish to pale orange-yellow in colour, and a pale muzzle with the paler area reaching to above, rather than below, the eyes. There are whorls on the forehead and behind the ears. (B144, B424, D246)
  • Tremarctos ornatus - Spectacled bear has thick, medium-length, black or brownish uniform-coloured fur, with large circular or semi-circular marks forming "spectacles" (rarely complete) around the eyes (black fur around the eyes and white markings forming circles outside this), and on the chin, neck and/or chest there is a creamy white or buff bib-like marking. (B144, B147, B288.w11, B285.w4)

For further descriptions and information on identification of the individual bear species see the species pages linked from List of Bear Species

Lagomorph Consideration Lagomorphs (rabbits, hares and pikas) can be distinguished from rodents by the presence of a second pair of incisor teeth behind the first pair; these cannot easily be seen. (B10.45.w47, B611.3.w3)

Care is required to distinguish between different lagomorph groups and species.

In the UK, the three species of wild lagomorphs can be distinguished as follows:

Further information on species identification and distinguishing features for individual species is provided on the species pages linked from the List of Lagomorph Species - SEARCH & List

Ferret Consideration While identification of many colours of domestic ferrets (e.g. albino or white ferrets) as ferrets is quite simple, it can be very difficult to distinguish between a polecat ferret (also known as a fitch - a domestic ferret with natural polecat colour markings) and a true polecat. A combinations of features are used to distinguish between true polecats and polecat ferrets. Ferrets usually have one or more of the following pelage characteristics: (B656)
  • Dark fur on face does not extend to nose.
  • Dark facial mask relatively pale or absent; pale check patches and frontal band extensive; reduced contrast between pale and dark areas.
  • Pale throat patch 50 mm long or longer.
  • One of more paws white.
  • While guard hares scattered over the body, particularly on the hindquarters and the tail.


Bonobo Consideration Bonobos were only recognised as a distinct species separate from Pan troglodytes - Chimpanzee relatively recently. Bonobos are distinguished by physical features as follows: 
Bonobo Chimpanzee
Face at birth black Face at birth pink
Lips red Lips brown or black
Almost no beard White beard in adults
Prominent side-whiskers from birth No side-whiskers
Hair on the head dense, even in adults Some adults develop a bald forehead
Body hair black (very rarely brown) Body hair tends to start black but turn lighter brown or grey in adults
Prominent white tail tuft of fur retained as adults White tail tuft of fur in juveniles only
Skull short and very rounded Skull longer, forehead lower, brow ridges more prominent
Eyes set further apart and less deep Eyes set closer together, more deepset
Clitoris large and shifted ventrally Clitoris not enlarged, not shifted ventrally.
Ears relatively small and set close to the head Ears larger and jut out more
In about 50% of individuals there is webbing on the feet, between the second and third toes Interdigital webbing is rare
Slightly shorter forelimb bones and significantly longer hindlimb bones; resultant horizontal body position when the individual is in a quadripedal stance Longer forelimbs than hindlimbs, so that the body is higher at the front than at the back when the individual stands quadripedally

(B580.3.w3, B577.1.w1)

It is important that bonobos are recognised as distinct from their close relatives, Pan troglodytes - Chimpanzee.

Differences from Pan troglodytes - Chimpanzees include:

  • Body more slender and forelimbs equal in length to hindlimbs, rather than longer than the hindlimbs.
  • Face black rather than pink, at birth.
  • Red rather than brown or black lips.
  • Practically no beard.
  • Shorter, more rounded skull.
  • Eyes further apart and less deeply set.
  • Brow ridge smaller and forehead rounder.
  • Smaller ears, set closer to the skull.
  • The white tail tuft is retained in adults.
  • Clitoris larger and more ventral.

See also: Pan paniscus - Bonobo - General Appearance 

Associated techniques linked from Wildpro

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Natural Markings

Use of natural markings and variations to identify individual animals has a long history. Where natural markings can be used in this way they have advantages of providing permanent identification without any interference with the animal. In the past, use of natural markings for recognition generally has been limited to species with clearly distinguishable coat patterns, recognition of individuals with marks such as scars, and long-term research where the researchers gradually learn to identify individuals within their study populations. Recently, computer aided recognition has been used and has widened the application of identification from natural markings. 

  • Individual characteristics commonly used for identification of individual animals include natural variations in coat or plumage colour and pattern, vibrissae-spot patterns, horn shape, or other characteristics, as well as clearly visible acquired marks such as scars, and other unique features. (J232.44.w1, B105.19.w6, B130.16.w2)
  • Ideally, natural markings used for individual animal identification will remain constant over the animal's lifetime.
    • Marks which change with time can be used only if the individuals are re-sighted frequently so that the changes can be incorporated into the description of the individual. (B130.16.w2)
  • Genetically determined pigment patterns are very stable and can be used to identify a variety of species such as zebras, giraffe and eland. (B130.16.w2)
  • The use of natural markings for identification is safe for the animal (requires 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 is sometimes used for behavioural studies on captive or free-living animals.
  • The presence or absence of hair whorls (cowlicks) in horses at a number of specified sites is commonly used for identification purposes. (B429.5.w5)
  • However:
  • 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 easy to record (by photograph, drawing and/or written description) and unmistakable.
  • Changes in markings/characteristics may occur with time, and this may cause mistakes in identification, particularly between similar individuals and/or when an observer or an individual animal has been absent for a period.
  • As with all identification methods, permanent records accurately showing the relevant identifiers (by photograph, drawing and/or written description) must be kept to minimize the potential for confusion.
  • New caretakers or keepers must learn to recognise the different individuals, which may take time, particularly if there are a large number of animals to be distinguished from one another.
  • Note: New work with computer-aided recognition has the potential to make individual identification by natural markings/variation much more widely applicable both in captive situations and in the wild. (J182.42.w1, J332.82.w1)
Hand and Foot Prints
  • Tracks have been used for many years in field work to identify species, indicate age and sometimes sex, and, where unique features are present (e.g. a misshapen foot, or a hoof with a piece of wall missing) even to identify and follow individuals.
  • Hand and foot prints of primates are, like human fingerprints, unique to the individual. They also show characteristics indicative of the species or larger taxonomic group. (B429.5.w5)
  • Hand and foot prints of primates are useful for long-term confirmation of identity, are inconspicuous, and their use is totally acceptable on humane grounds. (B429.5.w5)
  • Prints are not useful for daily identification; in most cases restraint (physical or chemical) is required to take prints. (B429.5.w5)
Nose prints
  • Nose prints can be used for identification of individuals of several species. (B429.5.w5)
  • These are useful for long-term confirmation of identity, are inconspicuous and their use is totally acceptable on humane grounds. (B429.5.w5)
  • Prints are not useful for daily identification; in most cases restraint (physical or chemical) is required to take prints. (B429.5.w5)
Ear prints
  • This has been developed for use in laboratory rodents. It is based on the unique branching patterns of blood vessels. (D381)

(B13.1.w18, B36.6.w6, B105.19.w6, B130.3.w1, B429.5.w5, D381, J182.42.w1, J232.44.w1, J332.82.w1, P4.1194.w3)

Bear Considerations
Click here for full page view with caption Click here for full-page view with caption

Natural markings may be used to distinguish individual bears in some circumstances.
  • In Tremarctos ornatus, the facial markings are unique to each individual bear (see: Spectacled bear Tremarctos ornatus - Appearance- Morphology- Skin-Coat-Pelage (Literature Reports)) and can therefore be used for identification. In Ursus thibetanus, the chest markings vary and can be used for identification of known individuals (see: Asiatic black bear Ursus thibetanus - Appearance- Morphology- Skin-Coat-Pelage (Literature Reports))
  • Some researchers have used the general appearance and/or coat colours of bears for identification. (D248.w3, B431.3.w3)
  • A long-term study of grizzly bears (Ursus arctos - Brown bear) in Mount McKinley National Park used combinations of individual characteristics such as coat colour, large scars and permanent lameness for identification. (B431.3.w3)
    • Families (females and cubs) were identified by the combined characteristics of the bears in the family, including for example the number of cubs, their age (cubs-of-the-year, yearlings, two-year-olds) and the relative sizes of the cubs as well as coat colours and any obvious distinguishing features. (B431.3.w3)
    • It was noted that coat colour could change considerably not only from moult to moult but also depending on light conditions. One bear was notable for fur which appeared very pale or very dark depending on the direction of the light, such that, at one time, it could appear pale on one side and dark on the other. (B431.3.w3)

Nose prints

  • Nose prints (several) of anaesthetised bears can be made onto paper (e.g. the back of a trapping/capture form) using tattooing ink; these can be used for future identification. (D249.w10)

Whisker spot patterns

  • In Ursus maritimus - Polar bear, whisker spot patterns can be used to identify individuals. An analysis of 50 such patterns found that 98% contained sufficient information to be reliable for identification. It was noted that pictures taken at less than 50 m from the bear were most useful for identification using whisker spot patterns. (J46.273.w2)
Lagomorph Consideration Natural markings can be used for identification if:
  • The rabbit has a unique coat colour or coat colour pattern within a group.
    • Coat colour and pattern are most useful for identification within a small group. (J83.27.w1)
    • Not useful for identification when rabbits of an identical strain are housed together
  • Injuries such as scars are unique for an individual within a group. 

(J83.27.w1, V.w5)

  • In the event of a rabbit being lost or stolen, photographs showing unique identifying features may be of some use to confirm identity of a rabbit. (V.w5)
Ferret Consideration
  • Facial markings do vary between individual ferrets. However, the markings on a given ferret can change from year to year, so facial markings are not suitable for a permanent identification record. Additionally, facial markings are not visible on albino ferrets. (B232.3.w3)
Bonobo Consideration Bonobos can be recognised as individuals without using any artificial markings. (B577.3.w3)
  • For identification of individuals in the wild, for behavioural studies, features which aid in identification include abnormalities such as extra nipples, or whitening of parts of the skin on the face or digits, as well as acquired physical abnormalities such as missing digits or larger limb defects, facial scarring and malformed lips. (B577.3.w3, B596.11.w11)

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Temporary Artificial Markings

Temporary artificial markings are useful when short-term identification of individuals or a sub-set of a population is needed. These marks usually do not harm or hurt the animal in any way, although care must be taken to consider the effects on thermoregulation and waterproofing if hair is clipped.

  • Appropriate placement should be considered carefully if the mark is to be easy to read by the observer, and bearing in mind the likely movement of the animal, e.g. on the flanks (one or both) or rump if using to identify herd species (and likely to be running away from the observer) or on the back if identifying from above. (V.w144)

Dyes, Sprays and Paints
  • Hair dying can be used to mark mammals of all sizes temporarily; dyes are particularly useful when the pelage is naturally light in colour. (J232.44.w1)
  • 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, distinguishing between neonates in a litter, for animals being transported to another location, or during short-term studies (e.g. during dispersal of groups of wild mammals following a disease management operation). (B105.19.w6, B429.5.w5, J23.8.w4, V.w5)
  • Dyes and paints usually mark the animals for less than a month; some human hair dyes are longer lasting. (B429.5.w5)
  • Paints or dyes used for marking mammals should be non-toxic and rapidly-drying.
  • Note: Care must be taken when using dyes on free-living mammals since the dye may have unknown effects on the animal's cryptic colouration (therefore on predation) and thermoregulation. (J232.44.w1)
  • Red dye, spray or paint should generally be avoided since this may be mistaken for blood by conspecifics or predators.
  • The time-span for which the mark lasts may be reduced due to excessive grooming, either by conspecifics or self (depending on accessibility). (V.w144)
Hair Clipping/shaving
  • Clipping or shaving the hair in a given site or pattern can be useful as a temporary marker until the clipped area grows out. (B130.12.w4, J232.44.w1)
    • In small mammals it may only allow identification for less than one month. (B130.12.w4)
    • In species in which the guard hairs and undercoat are of contrasting colours, clear marks can be made easily by clipping off the guard hairs only, so that the colour of the undercoats shows through, in areas of no more than 5 mm. Up to three such 5 mm patches may be clipped (no more), with coding based on a division of the dorsal surface into left and right and three sections from front to rear (shoulder, centre, flank). (B130.12.w4)
    • In larger species, numbers may be shaved into the fur or even written using a chemical depilatory. (B130.12.w4)
  • Shaving patterns into the hair is particularly useful for identifying shrews. (J232.44.w1)
  • In hedgehogs, areas of spines can be clipped short for similar marking. (B130.12.w4)
  • Fur shaving/clipping is painless and simple to carry out. (B130.12.w4)
  • Note: Shaving the hair may affect thermoregulation and the individual's ability to deal with its environment and with weather, therefore must be used with care in free-living mammals. (J232.44.w1)
Nocturnal lights
  • These can be attached to fur or to a collar and allow researchers to detect and follow the marked individual at night. They are temporary in nature, depending on the lifespan of the batteries used. (J232.44.w1)
  • Note: lights may attract predators. (J147.3.w1, P17.49.w1)
Fluorescent powders
  • These are used on small mammals for research. (J232.44.w1)
  • The powder trail left by the animal is visible with an ultraviolet light. (J232.44.w1)
  • The reliability of this method for tracking animals varies with precipitation and vegetation cover. (J232.44.w1)
Punch marking
  • In bats, a tattooing punch can be used to make a unique set of small holes in the wing membrane. The pattern of holes is legible for about five months. (J232.44.w1)

(B105.19.w6, B130.12.w4, B429.5.w5, J23.8.w4, J147.3.w1, J232.44.w1, P17.49.w1, V.w5, V.w144)

Bear Considerations

  • Dyes have been used to temporarily mark wild Ursus maritimus - Polar bear. (J40.35.w1, J343.52.w2)
    • In one study, the fur on the hip was cut in the shape of the last two digits of the bear's identity number and blue dye was then rubbed into the underfur using a toothbrush. This was visible for at least five months, and probably until the following moult. (J40.35.w1)
Lagomorph Consideration

Coloured wax on the ears to identify individual pygmy rabbits. Click here for full page view with caption.

Dyes, Sprays and Paints
  • Aqueous dyes can be used for temporary marking of rabbits. (B614.2.w2)
    • Marking with aqueous dyes is used in colony rabbits for temporary identification of young rabbits prior to weaning. (B614.2.w2)
  • Permanent dyes can be used but will fade as the animal moults. (J83.27.w1)
  • Sprays designed for use on sheep provide marks which last for about five to six weeks. (J83.27.w1)
  • A felt tip pen can be used on the outside of the ear and on the back. (J83.27.w1)
    • These markings need to be renewed weekly. (J83.27.w1)
    • With prolonged use, rabbits may develop dermatitis in reaction to chemicals in the ink. (J83.27.w1)
  • Xylene-free markers make marks which last about three weeks, and are non-toxic. (J83.27.w1)
  • Coloured wax has been used on the ear tips to identify individual. Brachylagus idahoensis - Pygmy rabbits. (V.w134)
  • Note: It may be difficult to see markings from dyes or felt pens on very dark coated (e.g. black) rabbits. (V.w5)
Hair Clipping/shaving
  • Fur clipping and depilation can be used for short-term marking; rapid growth of fur means that these markings last a few weeks; for longer use the marks have to be renewed frequently. (J40.18.w1, J83.27.w1)
  • Note: Round-tipped scissors may be preferable to powered clippers for trimming easily stressed animals. Powered clippers can act as an additionally stressor (vibration, noise) to an animal already experiencing a level of stress through capture, handling and restraint. (V.w144)
Ferret Consideration
  • In albino ferrets, dyes can be used for temporary identification. (B232.3.w3)
    • The dye must be re-applied frequently. (B232.3.w3)
    • Dyes are less useful in dark-coloured ferrets (e.g. polecat ferrets). (B232.3.w3)
  • Fluorescent coloured spray has been used for temporary marking of ferrets. (J288.115.w1)
Bonobo Consideration --

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Permanent Artificial Markings

A variety of methods have been used to permanently mark animals either to indicate ownership or to identify individuals. By their nature, permanent marking techniques are more invasive than are temporary marking techniques, and creating the marks may involve a certain, usually minor, amount of pain for the animal. Each permanent artificial marking method varies in its applicability to a given species, and on its use for different situations such as reading at a distance or confirming identity on close examination. Methods which are easy to read at a distance also tend to be more obtrusive to people (e.g. members of the public in a zoo) watching the animal.

  • Tattoos are widely used for permanent marking of mammals for identification. (B22.5.w2, B130.3.w1, J23.8.w2, J23.8.w3, J23.8.w4)
  • Tattoos are produced by injecting ink into the skin using an electric tattoo pencil or tattoo pliers, usually forming a series of numbers and/or letters. (B130.3.w1)
    • Green ink appears to be most useful, rather than black or red, particularly for use on dark-skinned animals. (B130.3.w1, B429.5.w5, J23.8.w3)
  • Tattoos can be applied to any area of skin which is relatively hairless and stays reasonably clean. (J232.44.w1)
    • Sites which have been used include the ear, axilla, medial thigh, ventral abdomen, ventral chest, foot and the inside of the lip. (B22.5.w2, B130.3.w1)
    • For use of tattoo pliers, it is necessary to have access to both the front and back surface of the area to be tattooed (e.g. a lip, ear or skin fold). Other areas can be tattooed using an electric tattooing instrument. (B429.5.w5)
  • Tattoos can be applied to mammals of all sizes. (B130.12.w4, J232.44.w1)
  • Tattooing of very small ears may damage the ear and should be avoided. (B429.5.w5)
  • Tattoos provide a permanent mark on the individual, are cheap to apply and any combination of letters/numbers may be used. (B22.5.w2)
  • 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. (B22.5.w2, J23.8.w7, J23.8.w8)
  • Incorrect technique results in tattoos fading and even disappearing completely over time. (B130.3.w1)
  • Tattoos may easily be copied to falsely certify a second individual.
  • Unless in an easily visible site, or with species which are very easy to handle, tattoos are useful in conjunction with other identifying marks rather than as the sole means of identification. (B130.3.w1)
  • Tattoos can be applied as follows:
    • Closely clip or shave the site, if haired. (B429.5.w5)
    • Clean the site thoroughly using alcohol, to remove oil and wax. (B429.5.w5)
    • Allow the alcohol to dry completely. (B429.5.w5)
    • Apply ink (preferably green) to the site.
    • Hold the animal securely to prevent (a) scratching the animal; (b) the tattoo becoming blurred. (B429.5.w5)
    • Make sure the far side of the ear or other tissue is padded (if tattoo pliers are being used). (B429.5.w5)
    • Apply the tattooing instrument to make the tattoo punctures. (B429.5.w5)
    • Rub tattooing ink into the punctures for at least one minute after the tattooing instrument has been removed. (B429.5.w5)
Freeze branding
  • Freeze branding is also called cryobranding. (J232.44.w1)
  • This uses a copper branding iron, supercooled using liquid nitrogen or a dry ice/alcohol mixture, and applied to an area of the body. (B22.5.w2, J232.44.w1)
    • The dry ice/alcohol mixture may produce better marks than liquid nitrogen. (B429.5.w5)
  • Immediately after application, the skin is frozen; as it thaws a reddened swelling appears, and one to two days later, a scruffy blistered mark is visible. The hair and superficial skin are shed after about three weeks to leave a bare mark, with white hair then appearing when the hair re-grows (e.g. one to three months). (B429.5.w5)
  • Properly applied, the melanocytes, which produce pigments, are killed, but the hair follicles are not, so the hair in the branded area grows back white. (B130.12.w4, J232.44.w1)
    • If the brand is held in place for too short a time, the hair does not lose pigment. (B130.12.w4)
    • If the brand is held in place for too long, hair regeneration is retarded. Additionally, the animal is unnecessarily stressed. (B130.12.w4)
  • Freeze branding can be used on mammals from the size of neonatal mice upwards. (B429.5.w5)
  • Freeze branding can be used to produce a variety of diverse, unique marks. (J232.44.w1)
  • Letters, numbers and symbols can be used. (B429.5.w5)
  • Note: the correct time for which the brand should be applied varies between species and for many species the ideal time has not been determined. (J232.44.w1)
  • Producing dependable freeze-brands requires experience. (J232.44.w1)
  • Note: hot-iron branding of the skin is more painful than is freeze branding and is not recommended. (B22.5.w2) Further information on pain associated with both hot iron and freeze branding is provided in Pain Prevention for Branding of Cattle (Techniques Overview)

Horn branding

  • In species with horns, it is possible to hot-iron brand marks onto the horns.
  • In some species this can be used in both males and females; in others only in males.
  • Branding on the inner surface of the horn is preferable, since this area is less subject to wear which may obscure the marks.

(B22.5.w2, J23.8.w9)

Ear clipping or punching

  • Ear clipping involves cutting V or U-shape wedges from the ear margins. (B429.5.w5) Ear punching involves punching circles out of the ear; a punch can be used on the edge of the ear as well as within the surface. 
  • Special plier-punches are available for this purpose.
  • Various coded systems may be used. (J232.44.w1)
  • A system using one or two notches per ear, at one of four sites on each ear, allows up to 99 individuals to be identified. Notches represent 1 (front of the ear margin) 2 (tip of the ear) 4 (rear of the ear margin, high up) and 7 (rear of the ear margin, low down) on one ear. On the other ear, the same marks represent 10, 20, 40 and 70. Apparently confusion may arise due to the left ear being used for the single digits in North America, but the right ear being used for these in Europe. (B429.5.w5)
  • When notching the ears:
    • In animals with long hair on the ears, clip the hair. (B429.5.w5)
    • Clean the ear with alcohol. (B429.5.w5)
    • Produce the notch of an appropriate size for the animal. (B429.5.w5)
    • If the ear bleeds excessively, control the bleeding using direct pressure, a coagulant such as ferric sulphate, haemostats, or clips which fall out after a short time. (B130.3.w1, B429.5.w5)
  • The advantages of ear notches are that they are inexpensive and permanent. They are also relatively inconspicuous. (B429.5.w5)
  • Disadvantages are that ear notches cannot necessarily be read at long distances; this is an injury (which must be considered and may be objected to on humane grounds); and there is always a risk of infection, as with other injuries. (B429.5.w5)
  • Natural holes or cuts may cause confusion. (B429.5.w5, J232.44.w1)

Foot web holes or slits

Toe clipping

  • This involves use of dissecting scissors or finger/toe nail clippers to remove the claw and first joint of one or more toes. (B22.5.w2 B429.5.w5, J232.44.w1)
    • It is recommended that a local anaesthetic agent and a coagulation agent should be applied. (B429.5.w5)
  • It is inexpensive, rapid and permanent. (B429.5.w5, J232.44.w1)
  • This marking method is painful, disfiguring, and may allow infection. (B22.5.w2)
  • Numbering systems may be complicated if an individual loses a digit through trauma. (B22.5.w2)
  • It is inconspicuous, but also not easy to read on animals unless they are restrained. (B429.5.w5)
  • It has been suggested that toe clipping may decrease the lifespan of some small mammals. (J232.44.w1)
  • Some researchers consider this an unethical mutilation to perform. (J232.44.w1)
    • Many zoo workers find it a distasteful operation to carry out. (B429.5.w5)
  • For some small mammals, toe clipping may be less detrimental than ear tags or other marks. (J232.44.w1)
  • Note: a recent study found that in reptiles, toe clipping may be a lesser stressor than microchip implantation, as indicated by hormone levels. (J422.209.w1)

Bear Considerations

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  • Bears can be tattooed in upper or lower lip, axilla, or groin. (B130.12.w4, B486.13.w13, D249.w10)
  • A lip tattoo can be used to identify bears as follows: (B130.3.w1, D247.7.w7, D249.w10, J40.35.w1, J46.234.w1, J332.86.w1, J345.14.w4)
    • Choose the tattoo site on the upper or lower lip. (B130.12.w4, D249.w10)
    • Rub the ink firmly into the intended tattoo site. (D249.w10)
    • Place the tattoo pliers with the desired numbers and letters in place and clamp down firmly for ten seconds. (D249.w10)
    • Check the pattern of punctures; the punctures can be re-nicked with a needle. (D249.w10)
    • Using a toothbrush with firm bristles, rub more ink into the tattoo area. (D249.w10)
    • Alternatively, a battery-operated tattoo gun can be used. (D249.w10)
  • For free-living bears, even if the tattoo is no longer legible, the presence of the ink smear indicates it has been caught previously. (D249.w10)
  • As well as tattooing, the ink can be rubbed into any cuts, or into the site where a premolar has been removed for age determination. These marks indicate that the bear has been caught previously.
  • If ink is present, then a combination of age, scars, other distinguishing marks, hair colour and sex may allow identification of the individual by comparing with records. (D249.w10)
Ear clipping or punching
  • Ear notching has been used for identification of bears. (D247.7.w7)
  • Note that these marks may be confused with natural holes and cuts, such that they are not then unique. (J232.44.w1)
Freeze branding
  • Freeze branding is effective in bears. (D249.w10)
  • This has limited use for marking of wild bears since it is impractical to carry the necessary equipment. (D249.w10)
Lagomorph Consideration Rabbits can be permanently identified by means of ear tattoos. In the USA, this is the required identification method for rabbits being exhibited. (B601.1.w1) Ear tattoos are used for individual identification of laboratory rabbits (B614.2.w2) and wild rabbits being studied. (B486.13.w13, J40.18.w10, J81.30.w1)
  • Tattoos do not disfigure the ear, and they provide permanent identification (unless the marked ear is very badly scratched or torn). (B614.2.w2, J40.18.w1)
  • A plier-type device can be used, with letters/numbers of an appropriate size. (B614.2.w2)
  • India ink is rubbed into the tattoo marks to produce the tattoo. (B614.2.w2)
  • In one study of wild rabbit, tattoos were applied with small tattoo pliers and indelible black ink; these were found to remain legible throughout the experiment in most cases. (B617.2.w2)


  • There is some discomfort to the rabbit when the tattoo is applied, particularly if it is not sedated or anaesthetised. (J83.27.w1)
  • High frequency sounds from a tattoo gun can be disturbing to lagomorphs. (J83.27.w1)
  • On rabbits with pigmented skin, it can be difficult to read tattoos. (J83.27.w1)
Ferret Consideration
  • Ferrets can be tattooed with an individual identification number or name on the inside of the thigh. The animal must be sedated and the area to be tattooed needs to be clipped for tattooing. (B232.3.w3)
  • Note: Two small blue dots tattooed on the ventral aspect of one ear is an indication (in the USA) of a ferret bred on a large farm and both neutered and descented before being sold. (J29.19.w1)
  • Toe clipping has been found not effective for identification of individual ferrets from tracks left  in ink-print tracking tunnels. (J209.24.w1)
Bonobo Consideration
  • Primates can be tattooed for identification, but reading the tattoos usually requires immobilisation, and tattoos may diffuse over time, requiring re-tattooing. (B671.12.w12)
  • On larger primates, the inner thigh is usually used for tattooing. (B10.44.w44f)

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Rings, Bands & Tags

Ear tags are commonly used for identification of mammals. Tags of a variety of sizes and designs have been developed for use in livestock, so they are cheap and readily available.
Placing ear tags

Plastic tags are usually made in two pieces, one with a hole and the other bearing a post with a sharpened point. Using an applicator, the point is driven through the ear and locked into the hole in the other piece of the tag. 

  • The skin should be clipped of excess hair and the skin cleaned with alcohol before the tag is put into place. (B429.5.w5)
  • For mature animals, the tag may need to be placed fairly high up, in the thinner part of the ear, while for young animals they need to be relatively near the base, in the thicker cartilage. (B429.5.w5)
  • For large animals with thick ears, it may be necessary to pierce the skin with a blade before the tag is placed in the ear (B429.5.w5) or to use a leather punch to make a hole through the ear. (D249.w10)
  • Care should be taken not to place the tag through any large blood vessels in the ear pinna. (B429.5.w5)
  • For animals with a curved pinna such that the two sides come round opposite one another, check that the point of the post of the tag is not going to rub against the other side of the ear. If it is, or might do, cut off and/or file down the point after the tag is in place. (B429.5.w5, V.w5)
  • Tags may be placed in the ears of hoofstock when they are a few days old (after a good maternal bond has formed but when they are still relatively easy to catch). (J23.8.w8)
  • Tags may be placed when the animal is being handled for another purpose. (J23.8.w5)
Ways to use ear tags for identification
  • Plastic tags can indicate identity by colour, colour combination (if there is a tag in each ear), and/or number. When tag colour or colour combination is used for identifying individuals, it is advisable to avoid using pairs of colours which may be mistaken for one another, particularly at a distance and/or with fading, such as blue and green, red and pink, black and purple or yellow and orange. (B429.5.w5, V.w5)
  • For numbered tags, the tag background colour can be chosen to blend in with the ear; this is not useful if it is the tag colour which is being used for identification. (B429.5.w5) Note that small numbers can be difficult to read at a distance, even with binoculars. (V.w5)
  • Tags of different colours can be used to indicate age groups of animals, with one colour being used for each year. (J23.8.w7)
  • Ear tags may be used to distinguish between males and females, by tagging males in the right ear, females in the left. (B429.5.w5)
  • Placing an identical tag into each ear reduces the information which can be carried but maintains identification even if one tag is lost. (B429.5.w5, B486.13.w13)
Tags for small mammals
  • Metal tags designed for use on fish fingerlings have been used for marking small mammals such as bats and rodents.
  • Tags have also been developed for small mammals by adaptation of metal clips used for closing surgical incisions.
  • Metal tags may be more likely to result in infection than plastic tags.
  • Streamers can be attached to tags for better detection and individual animal identification at a distance. (J232.44.w1)
  • Note: there is a risk that streamers may attract predators, interfere with normal behaviour or affect interactions with conspecifics.
Problems of ear tags
  • Some species and some individuals are intolerant of ear tags. (B130.3.w1, V.w5)
  • Some animals have granulation reactions to tags. (B130.3.w1)
  • Tissue arround the tag may become infected. (V.w5)
  • In small mammals with thin ears, tags may be likely to tear out of the ear, particularly e.g. in burrowing species. (J23.8.w8)
  • Note: some individuals lose ear tags. If this happens to more than one individual in a group then the identifying system may break down, so ideally ear tagging should be used in conjunction with a more permanent form of identification, such as tattooing. (B486.13.w13)
  • Collars or necklaces have been used on some small primates in captivity. (B22.5.w2)
    • The main disadvantages are that these are conspicuous, and that the animal may be injured if the collar/necklace gets caught on cage furnishings. (B22.5.w2)
  • Radiocollars are widely used for tracking of free-living mammals. (B486.14.w14)

Bear Considerations

Click here for full page view with caption Click here for full-page view with caption Click here for full-page view with caption Click here for full-page view with caption Click here for full-page view with caption

Ear Tags

Ear tags are commonly used in studies of bears in the wild to identify individual bears. (D248.w3, D249.w10, D283.w2, J40.32.w1, J40.35.w1, J46.234.w1, J332.65.w1, J332.86.w1, J343.52.w2, J345.14.w4)

  • Plastic Roto-tags and rubberised button tags are recommended as they appear to cause least irritation to the bear's ear. (D249.w10, J40.32.w1)
  • Metal paddle tags are preferred by some researchers. (D249.w10)
    • Metal tags were used to identify black bear cubs in a study in Pennsylvania. (J332.65.w1)
    • Metal tags with coloured nylon markers 3 by 4 inches in size were used to mark polar bears, also coloured collars. (J40.32.w1)
    • In a study of polar bears, metal tags were found to be problematic, with freezing and/or irritation leading to infection. (J40.32.w1)
  • Placing a tag in each ear is recommended as the chance of one tag being lost is quite high but the chance of both being lost is much lower. (D249.w10)
  • Losses of tags occur:
    • In males due to fighting. (D249.w10)
    • Cubs may chew tags off their mother or siblings. (D249.w10)
  • Tags of different sizes, shapes or colours may be used to distinguish between year, region or sexes. (D249.w10)
  • It is important to ensure that no tag use is duplicated, and that all tag use is recorded. (D249.w10)
  • Plastic streamers can be used with the tags. (B486.13.w13, D283.w2, J332.65.w1)
  • Ear tags may be used together with other means of identification such as transponders. (J40.65.w2)

Method of applying ear tags

  • Select a point midway in the back of the bear's ear, about 2.5 cm (one inch) from the outside edge of the ear. (D249.w10)
  • Using small scissors, trim the hair away from the site on both the outside and inside of the ear. (D249.w10)
  • Clean the site with alcohol. (B429.5.w5)
  • Check for and avoid any visible blood vessels. (D249.w10)
  • Use a leather punch to make a clean hole through the ear. (D249.w10)
  • Spray the wound with an antibiotic spray. (D249.w10)
  • Insert the tag using the appropriate tool, leaving the point of the tag to the outside of the ear. (D249.w10)
  • Record the colour and number of the tag (for tagging in the field, this should be recorded both on the capture sheet and on a master list). (D249.w10)
  • Streamers (e.g. 2 x 5 inches of Armatite or Ritchie Material, available in several colours) may be attached to the back of the button or Roto-tag and labelled using a permanent marker. (D249.w10)
    • This makes identification of individuals at a distance easier. (D249.w10)
  • Ear tags tend to break after about four or five years. (D249.w10)
  • Rips in the ears may indicate the previous presence of tags. (D249.w10)
  • Nylon collars have been used on polar bears. (B486.13.w13)
  • Radio collars used in studies of wild bears may be colour-coded. (D248.w3)
  • Radio collars can be marked by riveting coloured, marked Armatite streamers to the collar. (D249.w10)
Lagomorph Consideration

Breeders leg ring. Click here for full page view with caption

Sylvilagus backmani with ear tag. Click here for full page view with caption

Pygmy rabbit ready for release, with radiocollar. Click here for full page view with caption. Pygmy rabbit ready for release, with radiocollar. Click here for full page view with caption.

Leg rings
  • Rabbits can be identified by means of a leg ring, fitted around the hind leg just proximal to the tarsus. 
  • Both open and closed leg rings can be used. (J83.27.w1)
  • Most leg rings are aluminium; plastic rings are available. (J83.27.w1)
  • In the UK, closed leg rings are used for identification of pedigree rabbits. This is the required identification method for rabbits being exhibited. Rings are available in 10 sizes, appropriate for different breeds, only from the British Rabbit Council. The ring number is registered and if the rabbit is sold then the number is also transferred to the rabbit's purchaser. (B600.2.w2, B600.3.w3, B601.1.w1)
    • The British Rabbit Council rings bear a letter indicating ring size, and an individual identification number, as well as the birth year. (B600.3.w3)
  • The ring is fitted when the rabbit is about six weeks old. (J83.27.w1); when the rabbit is 8 - 10 weeks old. (B600.2.w2, B600.3.w3)
  • The leg should be checked regularly - weekly while the rabbit is growing, to make sure the ring des not become too tight. (J83.27.w1)
  • Leg rings can be irritating for the rabbit. (J83.27.w1)
  • Note: Fur and debris can get trapped beneath a leg ring, which can cause skin necrosis and infection. (B600.3.w3)
    • Daily checking of the ring and leg is recommended, or removal from pet rabbits (since they are not needed in a pet). (B600.3.w3)
  • Ring removal:
    • Removal requires chemical restraint of the rabbit and a hacksaw or a small saw on a power drill to cut through the ring.
    • Place something between the ring and the rabbits leg as protection during sawing (and to keep fur out of the way) - part of a wooden tongue depressor is suitable.
    • Cool the ring periodically during sawing, e.g. using cotton wool soaked in cold water.


Ear tags
  • Ear tags, either plastic or metal, can be used in lagomorphs. (B169.24.w24, B486.13.w13, B614.2.w2)
    • Numbered brass ear tags, 9 mm long, sold for use on the wings of chicks can be used to identify rabbits at three weeks old. The tag should be placed on the outer margin of the ear or at the tip of the ear. (B169.24.w24)
    • For rabbits which have grown to more than 900 g, a coloured numbered ear tag, 35 mm long (Dalton tag) can be used to allow identification at a longer distance. The tag should be placed at the base of the ear, in the cartilaginous part of the ear, with considerable care to avoid the longitudinal and transverse blood vessels. (B169.24.w24)
      • If the tag is placed higher in the ear there is greater risk of its being torn out through the thin skin. (B169.24.w24)
  • Ear tags can be placed quickly and easily. (B614.2.w2)
  • Insertion of the ear tag may be painful to the animal. (J83.27.w1)
  • Ear tags can be torn out of the ear, causing disfigurement (as well as loss of identification). (B614.2.w2, J83.27.w1)
  • Infections can occur, leading to chronic inflammatory response and growth of fibrous tissue in the ear. (J83.27.w1)
  • Ear tags were used for the identification of captive pikas (Ochotona princeps - American pika) at Denver Zoological Gardens. (J23.14.w6, P1.1972.w2)
  • At Chapultec Zoo, Mexico City, ear tags were used for identification of Romerolagus diazi - Volcano rabbit. Males were tagged in the right ear, females in the left ear. (J23.26.w2)
  • A variety of ear tags can be used for identification of individual wild lagomorphs.
    • Brass fish fingerling tags have been used for back-up or identification of re-captured rabbits.
    • Plastic or celluloid discs, two-figure numbers or figures in black on a white or yellow background, attached to the ear using a paper-clip like nickel or stainless steel pin, or a specially-designed aluminium rivet. A disc is placed on both surfaces of the ear (one numbered, the other a smaller backing disc). (J40.17.w2, J40.18.w1)
    • A piece of 8 mm diameter rigid plastic tubing, marked with up to four bands of coloured, self-adhesive, reflective tape, covered with two or three coats of polyurathane, sprayed on, for protection from wear, and attached to the ear with a piece of 0.8 mm diameter stainless steel wire, pieced through just above the dorsal cartilage ridge at the ear base. The completed tag weighs less than 1 g and can be fitted in under 30 s. (J47.20.w1)
    • Numbered chick wing-tags, placed in the left ear for females, right ear for males, giving instant identification of sex even when the number of the tag is not visible. (J81.30.w1, B617.2.w2)
    • Chick wing tags were used, "pinned low over the strong dorsal ridge of the ear close to the nape." With black letters on a white background, these could be read sometimes from as far as 100 feet (30 m) using a telescope. (B617.2.w2)
    • Plastic disks were used for tagging wild Lepus americanus - Snowshoe hare. (J343.40.w1)
    • Monel fingerling tags (numbered and colour-coded) can be used for identification of pikas (Ochotona sp.). (J332.66.w1)
    • Ear tags can be used with streamers. (B486.13.w13)
    • Metal ear tags have been used to identify riparian brush rabbits Sylvilagus bachmani riparius (Sylvilagus bachmani - Brush rabbit) in a propagation pen and individuals caught during censusing. (D377)
    • Note: It is important that the tags do not cause irritation and that they do not pull out. (J40.17.w2)
Collars, particularly collars holding radiotransmitters, have been used on a variety of lagomorph species, although some problems have been noted with collars of at least two different designs used on Sylvilagus bachmani - Brush rabbit.
  • Collars have been used for marking hares. (B486.13.w13)
  • Radio-collars have been used for tracking wild hares; they have been used for adults and (using transmitters weighing just 7.5 g) for leverets as young as five days old. (J40.35.w3, J46.273.w1)
  • Radiocollars have been used for tracking reintroduced Brachylagus idahoensis - Pygmy rabbits. A neck collar of a wire loop running through plastic tubing is used, clamped with a metal crimp at the appropriate length for each rabbit and attached to a 6 g radio with a six month battery life, and a whip antenna. (D373)
    • These are less than 2% of the rabbit's bodyweight. (W738.Dec08.w2)
  • Collars are not recommended for rabbits: they may fall off, the animal might get a leg caught in the collar, and another rabbit might chew through the collar. (J83.27.w1)
    • Note: in Sylvilagus bachmani - Brush rabbit in large enclosures, several rabbits got legs or jaws trapped in cable-tubing type collars. Strap collars used on translocated rabbits were also responsible for injuries (abrasions, wounds) and at least one death. (B623.w1)
      • The basic design of attachment for Holohil (Ontario, Canada) wire and Tygon tubing collarrs was considered not suited for this species, in which the neck diameter is nearly the same diameter as the head, and which are able to sometimes get one of their (short) front legs under the collar). (D377)
    • In Sylvilagus palustris - Marsh rabbits, 25 g transmitters on a neoprene-impregnated collar were used for longer study periods (to last up to about a year) and 7 g transmitters (170 day life) were used on a cable tie or nylon collar. Cable tie collars were modified to ensure they remained round, by using using Safe-Ty Low Profile Ties (Thomas and Metts, Memphis, Tennessee). (J59.34.w4)
Ferret Consideration Ear tags
  • Small ear tags can be used. They must be inserted on the lateral pinna, away from the central blood vessels. (B232.3.w3)
    • There is a tendency for ear tags to be pulled out, particularly when ferrets are group housed. This results in laceration of the ear. (B232.3.w3)
    • The small size of ear tags used in ferrets makes them difficult to read. (B232.3.w3)
  • Ear tags have been used in studies of feral ferrets. (J208.20.w2, J209.21.w1)
    • Size #1 Monel, National Band & Tag Co. ear tags have been used in ferrets. (J209.25.w1)


  • Collars can be used, but due to the narrow head and thick neck, they may easily be removed by the ferret unless applied tightly. (B232.3.w3)
    • It is important to ensure that the collar is not so tight that it cuts into the skin or interferes with breathing, particularly in young [growing] ferrets. The fit should be checked frequently. (B232.3.w3)
  • Radio-collars have been used in studies on feral ferrets. (J194.23.w1, J209.21.w1)
  • Radio-collars (rubber coated brass collars) were 27 g, which was up to 41% of the average body weight of ferrets; ferrets were only collared when at or near adult body weight, with weights of at least 630 g (female) or 930 g (males). (J209.22.w1)
Bonobo Consideration --

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Electronic Identification

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Microchips (transponders, PIT tags) are potentially permanent, unique identifiers which may be used in most animal species. Each transponder consists of a small cylinder of glass coated with special inert coating and containing a microchip with a unique electronic identifying number.

  • The PIT tag is made up of an electromagnetic coil and a custom-designed microchip; when excited by energy from a scanning wand, it emits an analog signal. Each chip is programmed with a unique alphanumeric code - more than 34 billion combinations are available. (J232.44.w1)
  • Transponders vary in size; larger transponders can be read at a greater distance. (B429.5.w5)
  • Microchips / transponders are implanted by injection, subcutaneously or intramuscularly, depending on the species the microchip is implanted in, using a wide-bore needle.
  • They can often be implanted without the use of anaesthetic agents, although a brief anaesthetic may be preferable for implantation in some species/individuals.
  • Microchips / transponders may be used in conjunction with more visible but less permanent markers such as tags or bands for daily identification of individuals.
  • Note: transponders can be removed from one individual and placed into another individual. This is most likely to occur in areas where the cost of the transponders is of concern. It is recommended that transponders are not re-used, since this can cause confusion in record systems; in particular, it is recommended that they not be re-used in animals which will be entered into ISIS/ZIMS. (D250)
Advantages of transponders
  • Microchips / transponders are ideal for entering into computerized record-keeping systems, such as ISIS (International Species Information System).
  • Microchipping may act as a deterrent to theft, as a transponder can be used to positively identify a recovered animal.
  • Microchips / transponders are visible radiographically; an x-ray can be taken to confirm or refute the presence of the transponder.
  • 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 (SSC) (B22.5.w2).
Disadvantages of transponders
  • Microchips / transponders need a special instrument to be placed in the animal, and a special scanner is needed to detect and read the transponder. 
  • 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 individuals are caught for management or veterinary purposes).
    • It has been suggested that transponders may have a failure rate of about 5%. (B429.5.w5)
  • Size constraints prevent the use of microchips in very small individuals.
  • Microchips are relatively expensive.
Choice of implantation site
  • The site chosen should:
    • Minimise discomfort of and risk to the animal; (D250)
    • Allow reliable reading of the transponder, with minimum migration of the transponder from the implantation site; (D250)
    • Be easy and safe for the operator to implant the transponder; (D250)
    • Be easy and safe for the operator to read the transponder. (D250)
  • Guidelines have been developed for the sites at which microchips / transponders should be implanted in different species. (D250)
  • Note: Transponders may be implanted into a variety of different sites. For detection of the transponder, it is necessary to (a) use the correct reader; (b) check the expected site but also other sites which might be used; (c) check around the potential sites, in case the transponder has moved. (V.w5)
Method of implantation
  • To implant a microchip subcutaneously in a mammal:
    • Scan the transponder to check that it is working,
    • Clean the intended implantation site with alcohol. (B429.5.w5)
    • Spread the hair (do not shave it). (B429.5.w5)
    • Hold the implanter needle bevel upwards at about a 45 degree angle to the skin and pierce the skin. (B429.5.w5)
    • Once the needle is through the skin, position it almost parallel to the skin and inject the transponder. (B429.5.w5)
    • Withdraw the application needle. (B429.5.w5)
    • Apply finger pressure to the application site for about 30 seconds. (B429.5.w5)
    • If there is an obvious wound left by the needle, glue the skin using tissue glue. (B429.5.w5)
    • Scan the site with the reader to check that the transponder is working. (B429.5.w5)
  • Note: In the EU, legislation (Regulation (EC) 338/97) requires that species listed under Annex A (mainly CITES Appendix I species) must be identified with a closed ring (not applicable for mammals) or a transponder that complies with ISO standards 11784:1996 and 11785:1996. (D250)

(B13.1.w18, B22.5.w2, P4.1994.w3, J232.44.w1)

Bear Considerations

Implantable transponder chips (microchips) can be used for the permanent identification of individual bears both in zoos and in the wild. (D250, J40.65.w2, J46.256.w1, J343.52.w2, J345.14.w1)
Site for implantation in bears
  • The EEP Ursid Husbandry Guidelines recommend subcutaneous implantation cranial to the scapular, next to the pre-scapular lymph node. (D247.7.w7)
  • The site recommended by BIAZA for implantation of transponders in bears is intramuscularly in the left supraspinatus muscle (i.e. over the front (anterior) part of the shoulder blade). (D250)
  • Subcutaneous implantation between the scapulars was used in a study of Ursus americanus - American black bear on a montane island in Texas. (J345.14.w1)
  • Sub-dermal implantation behind the ear [left or right ear not specified] has been used in studies of wild Ursus maritimus - Polar bears. (J46.256.w1, J332.86.w1)
Lagomorph Consideration


  • Transponders can be implanted when the rabbit is about six weeks old. (J83.27.w1)
  • Insertion of the transponder may cause some pain. (J83.27.w1)
  • Rabbits and similarly-sized mammals should have the microchip implanted between the scapulae. (B545.8.w8)
  • Subcutaneously implanted transponders have been used for individual identification of wild Lepus europaeus - Brown hares. (J503.35.w1)
  • Transponder readers are relatively expensive. (J83.27.w1)
  • Transponders were inserted in the shoulder region for individual identification of reintroduced Brachylagus idahoensis - Pygmy rabbits. (D373)
  • Transponders were placed subcutaneously in the inter-scapular area in Sylvilagus palustris - Marsh rabbit. (J59.34.w4)
  • Transponders have been used to identify riparian brush rabbits Sylvilagus bachmani riparius (Sylvilagus bachmani - Brush rabbit) in a propagation pen and individuals caught during censusing. (D377)
Ferret Consideration
  • Transponders are a good method for permanent identification of ferrets. The transponder is inserted subcutaneously between the shoulder blades. (B232.3.w3, B631.18.w18, J40.51.w1)
    • After insertion, palpate the microchip and move it by careful manual manipulation so that it is no longer directly aligned with the hole made during insertion - the microchip is then less likely to be groomed out by the ferret. consider using a drop of tissue glue to close the insertion hole. (B631.18.w18)
    • Note: the skin is thick here, particularly in adult males It may be necessary to anaesthetise the ferret and use a stab incision, implant the chip, then close the incision with a suture or with tissue adhesive. (B232.3.w3)
  • Note: Ferrets entering the UK from EU and some non-EU countries can enter without a quarantine period if they comply with certain rules. They must be identified by means of a transponder (and accompanied by an appropriate health certificate (W19.Oct11.w1) (pet passport) confirming appropriate vaccination and treatment against Echinococcus multilocularis and ticks. From 1st January 2011, treatment against ticks will no longer be a requirement for travel. (W66.Oct11.w1)
Bonobo Consideration
  • Ideally, all great apes should be fitted with transponders to ensure reliable identification. (D428.8.2.w8b)
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DNA "Fingerprinting"

DNA "fingerprinting" may be used for identification at both the species and the individual level.
  • A record is made from blood or hair 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 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.
  • 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. 

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

Bear Considerations

DNA may be collected from bears in the wild when they are being handled (D249.w10), or without handling, by setting up attractants surrounded by a single-strand barbed wire fence; bears investigating the attractant leave hairs caught in the barbs. (J59.27.w1, J179.2005online.w1)
Use of DNA analysis in bears
  • DNA analysis has been used in studies to indicate genetic relationships among bear species, and among populations within a given bear species. (J30.78.w2, J57.12.w3, J347.32.w1)
  • DNA analysis has been used to indicate paternity, such as the degree to which different males were siring bear cubs in a population, and to indicate the degree of relatedness among female bears in a population. (J30.82.w1, J346.86.w1)
  • DNA analysis has proved that bear cubs within a single litter may be sired by different fathers. (J30.82.w1)
  • DNA analysis has been used as one means of identifying which mammal had predated an Ursus americanus - American black bear, by analysis of DNA from cells on the scats (faeces) left near the bear's carcass. It was confirmed that the scats were from an Ursus arctos - Brown bear which, together with data from bite wounds on the carcass, indicated the black bear had been killed and eaten by an Ursus arctos. (J345.13.w1)
  • DNA analysis is not used as a routine means of identifying individual bears in captivity.
Lagomorph Consideration DNA analysis has been used in studies of wild lagomorphs for:
Ferret Consideration Genetically, mitochondrial DNA analysis has shown two mitochondrial haptotypes of polecats in Britain, a "Welsh polecat" type and a "domestic ferret" type. However, this is not sufficient to distinguish between domestic ferrets and wild polecats: the "domestic ferret" haplotype was also found in a phenotypically pure Mustela putorius - Polecat from Slovenia. (J17.87.w1)
Bonobo Consideration
  • Bonobos can be identified individually by DNA "fingerprinting". 
  • This has been used to determine paternity in both captive and wild bonobos. (J179.266.w1, P86.9.w1)
  • Comparison of mitochondrial haplotypes has been used to confirm that female bonobos within a wild community are unrelated to one another. (J179.266.w1)

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Authors & Referees


Debra Bourne MA VetMB PhD MRCVS (V.w5)


Liz Carter BSc MSC (V.w144); Neil Dorman (V.w104); Mike Jordan (V.w30); Chris Lasher (V.w110)

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