Equipment Requirements:

Each animal to be radio tracked must wear a transmitter with a signal that is picked up by the biologist-operated receiver. Also required is a directional antenna, which locates and magnifies the signal coming from the transmitter.

Weight:

There are potential detrimental effects of too much transmitter weight. If an animal is uncomfortable and thrown off balance by excessive weight, its movement will be influenced negatively. This in turn can cause physical harm to the animal and result in poor data collection.

For mammals, no more than 4-5% of the total body weight should go into the transmitter being carried. Birds, with a more delicate center of gravity during flight, should carry no more than 2-3% of their total body weight. Tiny species wear transmitters that are sealed with epoxy for waterproofing in order to cut down the transmitter's weight.

Shape:

Transmitter collars are the most common form of mounting for mammals. Birds can carry transmitters via backpacks, ponchos, tail clips and crop mounts.

An animal lacking a defined neck, such as an otter or snake or fish, will be a good candidate for implantable transmitters. Coated with epoxy or Elvax (a chemically inert mixture of paraffin wax and resin for toughness), the implantable transmitter is placed in the peritoneal cavity or between skin and muscle. The implanting surgery should be done quickly and with sterile techniques to prevent infection.

Habitat:

The animal's usual terrain will influence the packaging of the transmitter. If the transmitter is to be worn under water, hermetic sealing for complete waterproofing will normally be used and will add weight to the transmitter. Species that move underground or in water may have the transmitter implanted. The transmitter antenna is occasionally left outside the body. More often the antenna is implanted between skin and muscle; many researchers use a technique described in Copea(1982 (3): pp. 702-705) for inserting the antenna under the skin, especially for snakes. If the transmitter antenna is implanted, the signal will be cut down.

For animals that will move in brush, the transmitter antenna is often coated with heat-shrink insulated tubing to protect it from wear. Additionally, a transmitter antenna may be anchored to the collar with a cable tie to hold the antenna in an upright position for better tracking; the cable tie also prevents the antenna from catching on obstacles. If there is danger of breakage when the antenna is mounted externally, as with "tough" species such as bears and wolves, the transmitter antenna can be enclosed between layers of collar webbing. This internal antenna will shorten the transmitter's signal range.

For birds that wear transmitter backpacks, the transmitter antenna can be angled to 45 degrees so that the antenna flows back, parallel to the ground. This adaptation keeps the antenna away from the animal's body for better range.

Length of study:

The biologist's required study time will influence the battery that WMI technicians insert, as well as the pulse rate, width and peak current (duty cycle) of the transmitters they build.

Backpack harnessing fabric is chosen for wearing comfort and for planned obsolescence. For instance, a smooth and soft teflon ribbon makes a comfortable mounting; teflon is also durable for longer lasting studies. Polyester soft stretch elastic is used when the study is designed for a shorter period of time. The polyester elastic will not cause abrasions and will eventually disintegrate. This eliminates the possibility of an animal's carrying a nonfunctioning transmitter for the rest of its life.

Physiological changes during study:

To accommodate the growth of fawns and elk calves, for instance, the transmitter is mounted on a nylon webbed collar with elastic folds that allow for expansion. For male deer in rutting season, a collar of braided nylon-over-surgical tubing may be used to accommodate the change in neck size.

Baby birds such as turkey poults, as well as adults in short studies, can wear a transmitter glued on the back. A small patch of down must be removed and the area would then be shaved before the transmitter is glued on. As the bird's feathers grow, the transmitter is pushed off. Also, a saddle may be made of thin surgical rubber for baby birds.

Transmitters can be glued to adult bird's tail feathers; when the bird molts, the transmitter will fall off. Also, a transmitter may be mounted on a grooved base plate; cable ties, threaded in the grooves, will hold the transmitter at the front and rear when attached to the bird's tail feathers.

After transmitter mounting and before study begins:

We encourage wildlife biologists to observe a transmittered bird, amphibian or mammal closely before releasing to the wild. Does the species move normally? Has the fish "righted" itself to swim under its own power? Has proper balance been maintained? Does the transmitter fit well but not tightly? Does the transmitter slip or appear too loose, allowing a paw to get caught in the collar, which could then end up around the animal's chest? Are there skin abrasions that require medication? If so, the transmitter or anchoring knots may need adjustment.

We urge consultation between the project's wildlife researchers and Wildlife Materials consultants at this time. Procedures can be altered, problems can be adapted to and equipment retooled during this period.

During the study:

Sometimes a study provides information not previously known. For instance, a transmittered animal may scrape off a collar while moving underground due to unanticipated narrower openings between passages. The collars can be reshaped by WMI technicians to enhance the animals' wearing comfort in their habitat. Our technicians have long experience in adapting to a project's needs so that better study results will occur.