TECHNIQUES FOR MARKING WILDLIFE Nova J. Silvy, Roel R. Lopez, and Markus J. Peterson Department of Wildlife and Fisheries Sciences, Texas A&M University College Station, TX 77843, USA

Introduction All captive-animal and many field studies involving wildlife requires individuals be marked for future identification. Because of the wide diversity among vertebrate species, no single list of approved methods for marking is practical or desirable. The ultimate responsibility for the ethical and scientific validity of methods used rests with the investigator.

Considerations Prior to Marking Do the animals need to be marked or can natural markings be used instead? Do the animals need to be marked as individuals or can they be marked as a group? Do the animals need to be physically captured prior to marking or can they be marked without capture? How visible do the marks need to be and do the animals need to be “recaptured” for the mark to be observed? Will the marking method cause pain and/or decrease survival of the animal? Will the proposed mark affect the animal’s health, reproduction, movement patterns, and/or behavior? How long will the mark be required to last to complete the study and how durable is the proposed marking method? Will the proposed marking method interfere with other studies? Will the marks promote public concern about the study and will the marks have to be removed after study completion? Have the appropriate approvals (animal welfare and state and/or federal permits) to mark animals been obtained?

Techniques for Marking Wildlife Three main classes: Natural Noninvasive Invasive Marking techniques (natural marks) having the least adverse effect on animals should be used whenever possible. Invasive techniques have the greatest potential for adverse effects. Many techniques require capture, recapture, and handling that also might affect an animals’ behavior and survival. Separation of these effects from those caused directly by the marking method has yet to be evaluated in most cases.

Marking Permits Before an animal can be captured and marked, the appropriate local (e.g., animal welfare permits), federal, and/or state/provincial permits must be obtained. Wildlife species are regulated within state/provincial boarders by the appropriate wildlife agency. The federal government regulates capture and marking of migratory birds and threatened and endangered species.

Natural Marks Many animals exhibit unique coat patterns or can be identified by unique color patterns, scarring, fin or fluke notches, antler configuration, and/or other traits. Natural markings are most efficiently used on individuals with complex patterns, and analysis must be confined within a local population or region.

Unique spots and stripes on 2 bobcats

Marking as Individuals or Groups Many herd/flock movement and dispersal studies only require that large numbers of individuals be marked in a given area and relocated later. Many mark-recapture or mark-resight studies conducted to estimate population density do not require marked individuals be differentiated from another.

Marking Without Capture Remote marking of animals as individuals or groups has a long history. Marked with paint-tipped arrows and paint balls Manually triggered dye-spraying device Self-affixing collars Dyes can be introduced into the animal’s food to produce dyed fat, teeth, pelage, and droppings Dye-spraying devices affixed to aircraft Dyes also can be placed on eggs and nests, marking the adults as they incubate their eggs

Marking After Capture If animals must be captured, there are numerous marking techniques available. Although the most suitable marking techniques will depend on the needs of the investigator. Factors to consider are duration of study, ability to relocate marked animals, number of animals to be individually identified, and the effect of the mark on the animal.

Ideal Marking Technique (1) involve minimal pain or stress (2) produce no adverse effects on survival and behavior (3) permanently mark individuals (4) be easy to recognize at a distance (5) be easy to apply (6) be easy to obtain and/or assemble (7) be relatively inexpensive.

Retention Time of Marks Two categories relative to retention time: (1) permanent marks as those lasting the life of the animal (2) non-permanent marks as all others Permanent marks include branding, tattoos, ear notching, toe clipping, and other invasive techniques although scarring, tearing, and aging may reduce their effectiveness.

Noninvasive Marking Techniques Neck Collars Bands (arm and wing, flipper, leg) Nasal Discs and Saddles Back Packs, Harnesses, and Ponchos Trailing Devices Nocturnal Tracking Lights Tapes, Streamers, and Bells External Color Marks (Dyes, fluorescent pigments, bleaching, inks, and paints)

Oversized neck collar (right) that could allow animal to place leg through collar. Collar should fit snug around neck just below head (left).

Elastic (expandable) radio collar on white-tailed deer fawn (left) and a caribou cow (right) with radio collar and a highly visible numbered collar attached that allows for individual recognition of the animal if the radio transmitter fails

Expandable neck collars for male ungulates (left) and non-expandable female ungulate neck collar with holes for brass-split rivets (right).

Plastic neck collars on tundra swans

Standard butt-end bands used on the legs of birds (left) and butt-end aluminum band (right leg) and colored plastic band (left leg) placed on greater prairie-chicken (right).

Nasal saddle on the bill of a female mallard (left) and female black grouse with backpack tag (right).

Neck collar and ear streamer on white-tailed deer (left) and bell attached to collard peccary (right) that allows investigators to follow herd movements.  

Colored dye being applied with brush to the white portion of a white-winged dove wing.

Invasive Marking Techniques Internal Markers (chemical, particle, and radioactive) Transponders Tattoos Tags (ear, wing, body, jaw, and other appendages) Branding (hot, freeze, chemical, and laser) Tissue Removal (feather Imping and clipping; fur removal; shell notching; scale, toenail, and toe clipping; ear punching and notching; web punching; tail clipping; skin transplantation; and amputation)

Implanting a transponder (PIT tag) into a radio-marked fox squirrel (left) and numeric characters tattooed on the inside of an ear of a white-tailed deer (right).

Plastic numeric numbered tags attached to both ears of a collard peccary (left) and a plastic domestic livestock ear tag used on white-tailed deer (right).  

During the imping process (left), a feather of a captured bird (left) is clipped and a feather of contrasting color (right) is attached to it by means of a double-pointed needle. The right picture shows a patagial-wing markers on a least tern.

Freeze branding mark on hip of Thomson’s gazelle (left) and clipping the toenail (right) rather than the toe is preferred for short-term marking studies of small mammals.  

Using Multiple Marks It is best to use as few marks as needed to meet project objectives. However, there are times when multiple marks may be needed. For behavioral studies, highly visible marks are needed to observe an animal at a distance, but a radio collar may be needed to first locate the animal. In addition, a more permanent mark such as tattoos or PIT tags may be needed for long-term studies (e.g., survival studies). Use of as few marks as possible to complete the objectives of a study.

SUMMARY Natural markings are preferred Marking without capture is next best option For animals that must be captured prior to marking, noninvasive techniques are preferred Noninvasive methods generally are preferred Advantage of some invasive techniques is that many are “permanent” Multiple marks used only when it is absolutely necessary Ultimate responsibility on the ethical and scientific validity of methods used rests with the investigator.