When frogs laugh and call, Earthwatch vol­un­teers lis­ten and learn

The Weekend Australian - Travel - - Destination Australia - CATHER­INE MAR­SHALL

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.

earthwatch.org/australia

Emer­ald-spot­ted tree frog

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