Zoological Collections - Identification of Zoo Species

An essential part of managing collections is being able to identify individuals and what has happened to them during their lives. It also gives us a knowledge of ancestry for captive management programmes. Not being able to accurately identify individuals can lead to not recognising changes which might reflect their health or welfare status.

• temporary measure of identification can sometimes last for the animal's entire lifetime
• zoos must choose what method to use based on multiple factors:
  • the degree of handling necessary
    • all methods of artificial animal identification require the animal to be caught and handled for the feature to be applied
  • the potential for pain that may be experienced when applying the identifying feature
    • can vary from slight discomfort when applying leg rings to certain pain involved in applying ear tags
  • the longevity of the feature
    • how long it will be before the process needs to be replaced
    • longer lasting methods means the animal needs to be caught and handled less
  • impact the identifier has on the life of the animal
    • e.g., will the identifier affect the animal behaviourally or physically during its everyday life?
      • in one case study, captive zebra finches became attracted to multi-coloured leg rings. Males preferred black rings on females and females preffered red rings on males.
        • only happened when UV light was available in laboratory conditions
      • thought ear transmitters (with batteries) caused a lower chance of survival in wild moose calves

• Naturally occurring characteristics used in identification of individuals include colour or patterns in coat, feathers or skin; facial and bodily characteristics and features, including deformities such as twisted legs or scars; size and behaviour.
• Visible characteristics are an obvious and practical method of identifying individuals on a daily basis, but is reliant on the skills of the observer
• Many animal keepers are able to identify their animals just by using physical characteristics, but their ability to do this depends on their experience and familiarity with the animals
• Sometimes binoculars are used by keepers when enclosures enable animals to distance themselves from the keepers
• Using the stripe patterns on a certain area of the body can be used to identify zebra species and Okapi (Okapia johnstoni)

• The term ‘transponders’ may refer to devices with or without battery supply
• Transponders with battery supply are able to broadcast information whilst ones without battery supply require a device to read the information directly
• Within the zoo industry, ‘transponders’ and ‘microchips’ refer to transponders without battery supplies
• Not visible, but can migrate within the animal’s body and may no longer be able to be read
  • Can be groomed out by a conspecific
  • They are therefore not considered permanent

• often to reffered to as 'bands' in the USA
• Rings, collars, necklaces are thought to be the most benign of the types of artificial identification
• closed rings are slipped over the foot of a young bird with the intention that they will be permanent and never be removed
  • care to make sure the ring is big enough and does not become restrictive once the bird is an adult
  • can be difficult to remove if the bird injures itself and the leg becomes swollen
  • the ring may get caught in the bird's enclosure
• split rings are flexible
  • can be put on the animal's legs at any age
  • not necessarily secure
  • may be bitten or fall off 
  • reduced longevity
  • may need multiple applications if the ring falls off
• metal rings
  • secured in place with pinchers (ringing pliers)
  • the BTO states that 'placing a lightweight, uniquely numbered, metal ring around a bird's leg provides a reliable and harmelss method of identifying birds as individuals'
  • application requires a skilled professional, because the animal's limb could be damaged
  • usually used in long-lived species
  • metal can be worn and wear and tear could lead to the metal becoming sharp
• new materials are being used to make rings. A team from Bristol Zoo and the University of Bristol have created new silicone rings specifically designed for ease of application, and can stretch onto the penguin's flipper or bird's wing.

• requires the animal's skin to be perforated so that the identifying feature is fixed to the body
• best practice requires antiseptic
• used mostly on ungulates, but also on birds
• mammals are usually tagged young, sometimes at just one or two days old
• if tagging young care needs to be taken regarding potential aggression from the mother and the effects of restraint
• probably a painful event for the animal
• can be torn from the animal's ear

• Thought to include identification cuts, branding and tattooing
• All permanent methods of identification

• Works by embedding ink under the surface of the skin via injection
• Patterns of tattoo dots are used as a visible means of identification, whereby the position and number of dots identifies the animal
• Using secluded sites that have low pigmentation which mean the tattoo stands out more
• Can fade over time
• Tattoos can be hard to read when the skin becomes wrinkled or loose, which is common in older animals