Cryptic fauna among the cross words of environmental conflict

Miniature radio transmitter weighing 0.5gms glued to the fur of a Little Forest Bat, Vesperdalus vulturnus. The number is the frequency of the transmitter and is specific to that individual bat.

Radio-tracking: Rob Wheeler checking that the bat is flying successfully immediately upon its release in the early evening.

A giant tree; roost site selected by the diminutive Little Forest Bat, Vesperdalus vulturnus. Vegetation specialist Bill O'Shea provides a scale.

Woodchipping in the forests of the Eden region has been one of the most bitter environmental conflicts in Australia. Fauna conservation has always been a theme in this debate, albeit a minor one compared with the issue of conserving large tracts of forest as national parks. Now that the Regional Forest Agreement (RFA) of 1999 has been implemented, and the transfer of State Forests to National Parks has been settled, the more subtle subject of conserving fauna in commercial forests, i.e. those that will be logged, remains on the list of matters needing intelligent management decisions. Our national parks system will never be large enough to conserve all our biodiversity, so ecologically sustainable forest management is a necessary part of conserving species across the landscape. The focus in the RFA process was on threatened species, but there is more yet to do, especially with cryptic species, such as bats. Our research is tuned to the bats, a group of forest mammals that needs more research to help make the best management decisions.

Where the story began

Our study began in 1980 following a State Cabinet decision for the Department to examine the impact of woodchip logging on the fauna of the coastal forests near Bega. We took a bold step for the time and included bats among the fauna. In fact, we found that bats comprised one third of the list of the mammals of these forests. We also pioneered radio-tracking bats to their roosts. Our work was in Mumbulla State Forest, part of which became Biamanga National Park during the RFA process. We published that work, and it has helped to extricate bats from the list of species that were too hard to study.

Today’s story

Our current objective is to follow up on our efforts of 20+ years ago as the forest was being logged. Forests change, and it is sensible to make today’s management decisions on current information. To enable us to make the comparison over time as tight as possible, we went back to the same parts of the forest and reset the traps to catch the bats. The traps are the collapsible bat traps that were such an innovation when they appeared on the Australian scene in 1978. They have proved to be highly effective traps that do not harm the bats. We continue to use them.

The next step was to again place miniature radio-transmitters on the bats. Steady gains in technology have meant improvements in the transmitters. They are now less than one third of the weight that they were 20 years ago. This meant that we could not only use them on the bat we originally studied, Goulds Long-eared Bat Nyctophilus gouldi, but also on the smallest bat in the forest, the Eastern Forest Bat Vesperdalus vulturnus. It weighs 4 grams. (Reflect for a moment on how tiny this mammal really is. The world’s smallest mammal is a bat, weighing 2.5 grams. Thus one of our study animals is among the world’s smallest mammals.)

The results were amazing. The forest bats flew unerringly to the largest trees – giants that were about 1 metre in diameter. These roost trees were also characterised by rotting limbs, cracks in the trunk and other holes and entrances just the right size for a tiny bat to find a huge shelter. This means that these trees are old, and can be called old-growth elements in a forest that has been simplified by logging. The story is still unfolding, and we shall have much more to say in future editions. In the meantime, we are analysing our current records.

We remain indebted to the Foundation for its continued interest and support for this project.

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