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Capture & Telemetry

A lynx wearing a collar walks on a forest path and was photographed by a camera trap.
A lynx with a GPS collar. Camera trap picture, Jura mountains, 2017. © KORA

Lynx have been researched with the aid of telemetry in Switzerland since 1983. Telemetry stands for the wireless transmission of radio signals from a transmitter to a receiver. In order to observe large carnivores with the use of telemetry, they must be fitted with a radio collar containing an inbuilt transmitter. Consequently, the animal first needs to be captured and anesthetised to put the collar on it. Radio collars are adapted to the body size and weight of the captured animal. After reaching the end of its battery life, the collar falls off at a predetermined breaking point. The transmitter in the collar records the location of the individual. Besides the location, modern collars often also include sensors for the surveillance of other parameters such as temperature, activity, etc. Such data allow for answering various questions on diet, habitat use and demography.

Since 2005, KORA has also been using GPS systems, which have the advantage that locations are recorded automatically. At predetermined times, the GPS unit in the collar determines its location with the help of satellites and saves the information. The saved coordinates are sent to a ground station via the GSM mobile network or via an Iridium satellite. KORA can then process the data directly on the computer.

The radio collars also include a VHF (very high frequency) unit. This enables one to take bearings on the animals if the GSM system fails. The inaudible VHF signals from the collar are recorded by an antenna on a receiver. With a directional antenna, the direction of the signals origin can be determined. The own location and the direction of the signal are registered on a map. Repeating this process from different locations (cross bearing), the lines on the map will intersect at the location of the transmitter on the collar. In the mountains, this process is made more difficult by reflections of the signal off cliff faces, and deflections. Taking bearings requires a lot of experience – technically, in dealing with maps, and in the field.

Captures

There are a variety of methods that can be used for capturing wild large carnivores. For capturing lynx, we use three different trap systems:

Box traps

A box trap, painted yellow, black, stands on a path in the snow. The passage next to the box trap has been blocked with branches and nets.
A box trap installed for capturing lynx. © KORA

KORA uses box traps to capture lynx and wildcats. Box traps are made from solid wood. The inside walls are smooth in order to offer no points of attack for claws and teeth. When closed, the inside of the trap is dark and offers protection from cold and wet weather. The trap doors are triggered by an animal tripping over a trip wire across the middle of the trap or stepping on a seesaw inside the trap. The trap doors are constantly monitored with an electronic alarm so that the animal can be handled as quickly as possible.

Box traps are used in winter on forest roads and game trails. Lynx tend to use such man-made tracks especially when the snow cover is high. The most successful time of the year is around the breeding season between February and April when lynx travel around more. The passage on each side of the trap is hindered with the use of branches and camouflage nets. Thus, the easiest way leads through the box trap. Box traps for wildcats are not necessarily set on trails or roads. Moreover, a valerian lure is added to those traps. Traps are always set only after coordination with the respective canton. Signs inform passers-by about the trap. For every capture, the animal is anesthetised, examined, equipped with a radio collar and released again as quickly as possible.

Snare traps

KORA uses foot snare traps to capture lynx. Foot snares are efficient and safe. They are usually set nearby an animal killed by a lynx. Each trap consists of a round stepping board, two jaws, one wire snare and a trap tube. The stepping board and the jaws serve as a throwing mechanism for the snare. When a lynx touches the stepping board, the jaws throw the snare up and over its paw. It is thus restrained by the snare and the trap tube which is anchored in the ground. The trap tube contains a spring which dampens the jerky movements of the lynx. The traps are continuously surveyed with a VHF transmitter. As soon as the trap is triggered, the alarm is set off. The capture team is waiting nearby. As soon as the lynx is trapped, it is anesthetised, examined, equipped with a radio collar and released again. The complete snare trap set as used by KORA can be ordered from KORA.

Minimally Invasive Capture System MICS

The MICS is installed on a tree in the forest.
The Minimally Invasive Capture System MICS is mounted to capture a lynx. The MICS is a remote controlled tranquilizer gun. © Laurent Geslin

KORA uses the MICS to capture lynx. MICS is a remote controlled tranquilizer gun. The tranquilizer gun can be controlled on a monitor from a distance of up to 800 m. The MICS is usually set nearby an animal killed by a lynx. With the aid of an inbuilt camera, a monitor and the remote control, accurate shots are possible up to a distance of 25 m. The device also contains an infrared camera and an infrared spotlight. Motion detectors alert the capture team when an animal approaches the kill. The tranquiliser darts contain a VHF transmitter to help find the lynx after firing the tranquiliser. The advantage of the MICS is the relatively stressless capture of the animal. However, as the animal is not physically restrained and can still move after being hit with the tranquilising dart, the MICS cannot be used if there are dangerous elements in the vicinity, like a busy street, water courses, or steep rock formations. The MICS can be ordered from KORA.

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