When frogs laugh and call, Earthwatch volunteers listen and learn
IN a photograph of a sweet little frog cupped gently in Alan Lane’s right hand, you can see the fine sprinkling of emerald spots on the amphibian’s back and the bright yellow flashes that run along its inner thighs.
‘ ‘ Its common name is the emerald-spotted tree frog or the laughing frog because of its maniacal cackling call,’’ Lane says affectionately.
At his home in Blackheath in the Blue Mountains west of Sydney, the retired microbiologist has regular conversations with the frogs in the spring when they start to call from a nearby creek..
And he’s got lots to tell them. Lane has twice volunteered on Earthwatch’s Vanishing Frogs expedition where he has watched with interest as the puzzle of a diminishing frog population is gradually pieced together.
‘‘I was fascinated to learn that the causative agent of collapsing frog populations was identified as a fungus, chytrid, which was attacking the frogs,’’ Lane says. ‘‘It was a puzzle as to why it was so extremely virulent and so fatal.’’
In an effort to untangle this and other mysteries surrounding the steady decline of frog populations, Earthwatch leads expeditions into the mountain forests of NSW’S Hunter region. Under the guidance of Michael Mahony, an associate professor at Newcastle University, volunteers collect data that will help him to determine the impact of chytrid on frog populations and to ascertain why the fungus is present in specimens collected and preserved long before the disease first emerged.
‘‘Has it mutated and suddenly become more virulent, or is there some other factor at play which is making the frogs more susceptible?’’ Lane asks.
The answers lie somewhere along a creek bank where, in the dead of night, Lane and his fellow volunteers don head torches and work their way upstream in search of frogs.
‘‘The way you find frogs at night is by looking for their eye shine — it is very, very pale pink,’’ he explains. ‘‘If you’re careful, you can identify where a frog’s calling from — some frogs reply if you call.
‘‘You pounce on the frog, put it in a plastic bag, mark where you found it with a piece of ribbon, take it down to Michael [Mahony] and then you put it back in the plastic bag and take it back to exactly the spot where you got it from, take the piece of ribbon away and let the frog get on with its day.’’
Frogs that have been microchipped give clues to the animals’ range and longevity — vital information when determining the sustainability of their population. And beyond the invaluable task of capturing these creatures, volunteers have also contributed to the discovery of four new frog species.
Lane, who has also volunteered on Earthwatch’s platypus and dinosaur expeditions, didn’t expect the frog project to have quite so profound an effect on him.
After retirement he returned to university to do a master’s degree on the effects of urbanisation on frog populations and co-authored a children’s book, Saving Frogs, with his wife, Virginia King.
Lane has also helped his local volunteer bush care group to eradicate willow from the creek near his home, and is happy to report that frogs, such as that emeraldspotted tree frog with its rousing laugh, are returning to the re-vegetated creek.
‘ ‘ It was a completely sterile habitat before, nothing lived there except the willows. Now it’s a thriving wetland and last spring and early summer, when the frogs were calling I was able to identify five different kinds of frogs in an area that was previously completely devoid of wildlife.
‘‘So I go down and talk to them, and listen to them,’’ Lane says.
Emerald-spotted tree frog