A network of solar powered mini-computers that ''talk'' to each other is tracking the return of rare frogs to Australia's rainforests and will record the antics of Santa's reindeer at a zoo in Lappland.

The world's biggest outdoor wireless sensor network, developed by CSIRO, will be installed by Ume University at Sweden's northernmost zoo at Lycksele.

''It's not just a webcam in a tree. This is a complex system of cameras and microphones that monitor the animals' behaviour, and save energy and time by filtering out the boring bits,'' CSIRO wireless sensor research leader, Dr Michael Bruenig said.

The remote sensing system, developed to track cattle in Queensland's outback rangelands, is revolutionising the way environmental scientists are gathering data.

At Lycksele, the network (called a Fleck system) will analyse video and audio data collected by 100 solar-powered sensor nodes which typically contain a mini-computer, radio transceiver, tiny camera and light and temperature sensors.

CSIRO senior research scientist Dr Tim Wark said setting up the Lycksele network would be '' particularly challenging'' because there is little sunlight during winter and temperatures can drop to a camera-freezing minus 30 degrees.

Meanwhile, in Queensland, a network of 10 sensors is monitoring the return of frogs, birds and bats to areas of regenerating rainforest in the Springbrook World Heritage area. The wireless sensor nodes relay information to a base station or by ''hopping'' transmissions along the network.