By Dr Andrew Carter, Wildlife Ecologist
Fitting wildlife with tracking devices is an important part of the work AWC does across the country. Tracking is undertaken to monitor the survival of native mammals re-introduced inside fenced, feral predator-free areas or to better understand the effects of management activities on the spatial ecology of wildlife in open (unfenced) landscapes.
Satellite-based transmitters can send location data remotely without the need to relocate the tagged animal, but the size of this technology means that, at present, it can only be fitted to species that weigh more than three kilograms. To obtain location data from telemetry tags fitted to smaller species, it is necessary to maintain contact with the tagged animals. This can be done actively from the ground via vehicle or foot-based searches, but such an approach is very time consuming as detection distances are usually short (up to two kilometres).
Another option is to use base stations that download location data automatically when a tagged animal is nearby. These can either be fitted to fixed towers and left unattended at strategic locations, or mounted to unmanned aerial vehicles (‘drones’) for active searching. Fixed towers are difficult to build in remote locations and once erected cannot easily be moved elsewhere, while drones can only be flown for short periods at a time.
In a search for a more efficient and effective solution for downloading wildlife telemetry data, AWC recently trialled an alternative approach—a tethered helium balloon. The week-long trial, which took place in September in the Pilliga State Conservation Area and Pilliga National Park, in northern New South Wales, was the first of its kind in the southern hemisphere to use this type of balloon for wildlife research.
Developed by French company, EONEF (eonef.com), the balloon is made with a gas-proof, multilayer, plastic membrane, and is filled with 10 cubic metres of helium. Tethered to the ground with a nylon cable, it can be flown at heights of up to 120 metres, and returned to the ground using a winch. Measuring approximately 4.3 metres long by two metres wide and two metres high, the balloon can be set up by one person and is capable of flying unattended for weeks at a time. It can be fitted with solar panels to maintain power to the telemetry base station that is attached to its undercarriage.
In the forested landscape of the Pilliga, the balloon was able to download data from telemetry tags located nine kilometres away. That equates to an effective detection area exceeding 25,000 hectares, which suggests that a single tethered helium balloon could provide download coverage across any of AWC’s current fenced reserves — greatly improving the efficiency of obtaining location data from tagged animals.
The next stage of development for the balloon is to automate its operation so it can be raised and lowered to the ground remotely to safeguard against adverse weather conditions. This approach would open up endless possibilities for monitoring wildlife in even the most remote locations.