Magazine Article 1997 – Radio-Tracking Possums

He Korero Paihama   No. 6 March 1997

Radio-Tracking Possums

Did you know that the first wild animal to carry a radio transmitter in New Zealand was a possum? It was fitted on 17 December 1968, in the Orongorongo valley near Wellington. The transmitter ran on a pen-light sized mercury battery and weighed a massive 80g. It had a range of about 100m and a life of three months.

That huge, grossly inefficient transmitter carried by a rather stressed possum was built by Larry Keuchle who, seventeen years later, left research to start “Advanced Telemetry Systems” in Minnesota. It was built as a demonstration for Dave Ward who now manages Sirtrack Ltd (a subsidiary of Landcare Research), which manufactures telemetry equipment for a wide range of uses. And as for the possum – it survived the experience to become the first of many hundreds of possums that were, and still are, being radio-tagged in the Orongorongo valley.

The technology has been applied to many other species and since 1968 radio-tracking has advanced considerably. A major shift in frequency from 27MHz to 160MHz during the seventies did much to improve the performance of the equipment, and possum trackers no longer had their nightly beep-beep-beeps interrupted by citizen band radios operating on similar frequencies. A typical transmitter package for possums today weighs around 25g, will run for 15 months, and has a range of several kilometres. Furthermore, the transmitter can be fitted with options to sense such things as body temperature, heart-rate, sound, or death. New types of transmitters will turn themselves on at predetermined times, or will turn themselves on and off in a cyclical way to prolong battery life. Today Sirtrack transmitters are used on more than two hundred species of wildlife living in a wide range of habitats around the world. Notable examples include frogs living in the Alaskan tundra, antelope in swamps in East Africa, camels in deserts in North Australia, weta in rain forests in New Zealand, and penguins on ice floes and in the sea about Antarctica.

Progress with other radio-tracking equipment has been more variable. Receivers are shrinking and becoming even more portable but the efficiency of tracking antennae is about as good as it is going to get. Users really are stuck with their current size for the time being.

Photo caption – Dave Ward is Manager of SIRTRACK Ltd, based at Havelock North.

Photo caption – Possum fitted with a radio collar.

Handwritten note – (Published by Landcare Research NZ Ltd)