Press Report

Answering the call

Rosslyn Beeby
Monday, 25 September 2006

'HEAR that scratchy sort of corkscrew call? Wee-cha-choo? That's the eastern bristle bird," Australian National University field ecologist Chris MacGregor says, methodically noting the bird's presence on a data sheet, while keeping a well-attuned ear out for other early morning callers.

And the sound like grinding scissors? That's the leaden fly catcher. Hear that pip-pip-pollwee? That's the call of the GST, or grey shrike thrush.

It's not yet 7am, but MacGregor and his team of bird call specialists have been at work for several hours and have already assessed bird life at around a dozen sites throughout Booderee National Park, at Jervis Bay in southern NSW.

Unless the temperature rises fairly quickly on this sunny spring morning (the birds stop calling as the morning gets hotter) the team has another two hours of work ahead of them - methodically ticking off calls, estimating the distance and habitat that various species appear to be calling from, as well as recording sightings of any birds flying overhead and jotting down anything unusual about calls or behaviour.

"Sometimes you hear something that throws you. It might be a bird you weren't expecting to be calling, or a variation in a call that's unlike anything you've heard before, or you might be lucky enough to see a bird on a nest. All those things are important," MacGregor says.

The surveys are a vital part of Australia's biggest study of the impact of fire on wildlife and vegetation - the Jervis Bay Fire Response Study, established in 2003 by ANU ecologist Professor David Lindenmayer.

There are 110 observation sites spread across Booderee National Park, and during the spring bird survey each site is assessed twice over a five-day period. All sites have two listening points - one at 20m in from a road or dirt track, the other at 80m - where observers note the number of birds calling over a five-minute period. It's like a rapid-fire aural quiz, or bird call blitz. Accuracy is critical and error could skew research findings, so this is definitely not just a walk in the park. It's world-class, world-first science.

"Each site is revisited at a different time of the morning from the first assessment. We also send a different observer into the site to listen and record the calls," MacGregor says.

It's precision work that uses the skills of a crack team mustered from the Canberra Ornitholgists Group - a team that includes CSIRO scientists, retired senior public servants, diplomats and, most importantly, a statistician.

Dr Peter Fullagar, a CSIRO honorary research fellow, set up the National Wildlife Sound Collection and is probably Australia's leading expert on bird vocalisations. He's making recordings at most of the sites.

Peter Roberts, Mike Doyle, Terry Munroe, Jenny Bounds, Bruce Lindenmayer and Ian Anderson are veterans of seasonal bird surveys with the Canberra Ornitholgists Group and national Bird Atlas surveys.

All have the finely-tuned aural skills of a symphony orchestra conductor, and can tune into the multi-layered calls of a dawn chorus, quickly sifting wrens (variegated, emu and fairy) from trillers and tree-creepers.

Don't call them "twitchers". These are serious ornithologists.

"Twitchers are like train spotters, compared to the specialised work we're doing," Bounds, a retired public servant and former COG president who contributes bird distribution data to the annual State of Australia's Birds report, says. "Twitchers are more concerned with seeing birds, rather than listening or recording behaviour. This kind of work is highly skilled and it's the only survey of its kind in Australia. There wouldn't be too many people who could do it, because it takes years of experience to get your ear around all the different calls and the regional variations of those calls.

"We've got five minutes to log calls, so you haven't got time to stop and think about what it is that you might have heard."

Carefully picking her way through waist-high bracken, heading for a spot marked by pink tape, Bounds checks her watch and her pencil starts skimming over the data sheet. After five minutes, she heads to the 80m checkpoint, obscured from sight by shrubs and ferns.

"It's not easy-going at some of these sites. There are no paths and you've got to watch your feet because you're continually stepping over logs and branches," she says.

And judging from talk around the barbecue the previous night, it's also wise to keep an eye, and ear, out for chunky little snakes called death adders. They're apparently fast and venomous.

"No, you wouldn't want to stand on one of them, but if you make enough noise walking through the bush they tend to get out of the way," Bounds says.

So how did she fare at these first early morning sites? To amateur ears, the dawn chorus sounds like a chirping cacophony with a few obvious notes ringing out from an eastern whip bird.

"I've got brown gerygones, brown thornbills, eastern yellow robins, Lewins honeyeater, rainbow lorikeets, grey butcher bird, variegated fairy wrens, red wattlebirds and a rufous fantail. They're a migratory species, so it's good to see they're coming back," Bounds says.

The next site is easier to negotiate - a brisk walk through low clumps of vegetation, down to a valley floor ringed by forest. It sounds busy with birdlife, but Bounds explains that despite the variety of calls, there isn't really much bird activity.

"There's not much actually calling in this site. Everything is calling from the woodland beyond. The only calls I've picked up here are a couple of wrens, a brown thornbill and an eastern spinebill."

MacGregor later explains that surveys get quite tricky when a site is comparatively quiet.

"That's where you need the experience and ear for bird calls. When it's quiet, you can start picking up on birds that are a lot further away than the site you're recording. You've got to be careful to stick with the vegetation type you're recording and not list calls straying in from different vegetation. You've got to be discriminating about what you're hearing."

Hear those red wattlebirds? Their call might be distinct and easy to identify, but they don't make the cut - at least not for the heathland site that MacGregor's assessing.

"There's no point recording them because they're too far away and are probably calling from the trees over there. That's not what I'm listening for at this site. I want the heathland birds."

He explains that the Jervis Bay fire recovery survey sites are the result of complex computer mapping of differing vegetation types and statistical sampling.

MacGregor is based at Jervis Bay and co-ordinates the various fauna surveys for the project, which include mammals, marsupials, reptiles and birds. He's specifically researching the habitat use and nesting habits of ringtail possums and long-nosed bandicoots.

"We set up this study because the impact of prescribed burning and feral baiting programs on ecosystems wasn't well understood, " Professor Lindenmayer says.

"There's remarkably little data on long-term ecological impacts of fire. How can you manage an ecosystem if you don't know what you're managing for?"

Fire burned across much of Booderee in 2003, destroying most of the sites he'd set up with MacGregor, so Lindenmayer switched the research focus from prescribed burning to fire recovery.

The study has already delivered some surprising findings, and Lindenmayer's research team is poised to "deliver some massive papers on birds and mammals" within the next six months.

One of the most unexpected findings has involved the endangered eastern bristle bird, which was thought to be restricted in its distribution to a few areas of dense, unburned coastal heath.

"About a year after the fire, we began recording them all over the park. The foxes probably weren't going after them in the dense heath, but when we knocked out the foxes with a baiting program, the birds began moving out into the park.

"So now, we're learning a lot more about them and the other animals in the park. We're getting some fascinating results."

Canberra Times link at:http://canberra.yourguide.com.au/detail.asp?class=news&subclass=environment&story_id=512039&category=Environment&m=9&y=2006

Members of the Canberra Ornithologists Group and staff from the ANU Centre for Resource and Environmental Studies participating in the Fauna/Fire Response Study being conducted by CRES at Booderee National Park, Jervis Bay Territory.

September 25^th 2006 off picture gallery at: http://www.bobmcmullan.com/