Confessions Of A Koala Counter – Night Surveys Monitor Koala Population In Bongil Bongil National Park

Ian Scott records his team’s results. Photo: Andrew Vivian.

 

BONGIL Bongil National Park is estimated to contain around 500 koalas, and has one of the genetically-strongest populations in the country.

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Each year, night surveys are conducted to check on the health and distribution of koalas in the park.

Volunteers, in five groups of up to eight people, conduct five surveys over a three week period and rotate through five different forest tracks on each survey night.

Three days are left between each survey, to allow for movement of koalas.

According to ranger Martin Smith, actual counting of koalas is almost impossible because of their colouring, and their ability to bundle into a ball in the fork of a tree, which makes actually seeing a koala very difficult.

Mr Smith said, “The park is 4300 hectares in area, so the average area for each koala is 8.6 hectares.”

“There is approximately one suitable tree every 4m2 for a koala to climb in the park, which approximates to 21,000 trees for each koala,” he said.

Therefore, a sampling method is used.

Five 1.5km stretches of forest track have been selected for the surveys because they are prime koala habitats.

The forest on each side of the track is scanned, using torches, for the glint of reflected eyes in a tree.

Sightings are not as common, however, as auditory signs of koalas.

Each team has a loud hailer and an iPod on which a koala mating call is recorded.

At 500m intervals along each track, the calls are played three times and team members spread out along the track to listen for a response – a male koala will bellow a challenge to any other nearby males.

Teams estimate the direction and distance of any koala calls.

They also record koalas and any other animals that are sighted.

(Last week, three possums, a three-metre carpet python and a 70cm Tiger snake were encountered.)

After three out of the five surveys, teams have heard fourteen koalas and sighted two.

The previous two years have resulted in 23 and 24 contacts with koalas, across all five surveys.

Indications, so far, are that the Bongil Bongil koalas, unlike those in many other areas, are doing well.

 

By Andrew VIVIAN

 

Looking for the gleam of koala eyes. Photo: Andrew Vivian.

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