EXPEDITION REPORT - Biosphere Expeditions

Radio Telemetry
The VHF radio collars, receiver, headphones and antenna used in this study are from ATS
(Advanced Telemetry Systems) in Minnesota, USA. The collars weigh 240 g, which is less
than one per cent of the study animal’s body mass. They are fitted with activity and
mortality sensors and emit three types of signals: resting signal - regular single signals
when the animal is resting; activity signal - irregular signals of different rhythm when the
animal is walking or running; mortality signal - regular single signals, but twice as frequent
as the resting signal when either the collar was lost or the animal was dead
The collars are equipped with a VHF antenna, 30 cm in length, extending 17cm from the
collar. The other half of the antenna is embedded in the collar band. The batteries of the
collars last for approximately three years.
Every day the telemetry team covered central parts of the study area. To locate collared
animals, the team stopped at vantage points (Figure 2.5.2.b) and tried to receive signals
emanating from the surrounding area with the radio telemetry equipment (see cover page).
At every stop the date, the time and the GPS position were recorded using a Silva Multi-
Navigator. If a signal was detected, the signal bearing was measured with a Silva
compass. The strength of the signal and the activity status of the study animal were
recorded, too.
Figure 2.5.2.b. Map of the study area with fixed spots (vantage points) to perform ground telemetry.
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