SA Government Koala figures incorrect: AKF

20th July 2015 article from The Australian- 'South Australia Koala Cull not on horizon: Ian Hunter' 

 

The South Australian State Government has unveiled a draft for its Koala Conservation and Management Strategy. As stated in the above article, South Australian Government figures estimate that there are between 114,000 and 200,000 Koalas in the Adelaide Hills.

The AKF is of the view that this is completely incorrect, with Koala numbers in South Australia more likely to be in the range of 12,180 - 13,870. Citizen science surveys, which are well meaning, were used in this case, and may have little scientific merit. 

AKF Landscape Ecologist, Dave Mitchell believes that with its population estimate of 114,000 - 200,000, the South Australian Government appears to have fallen into the age-old trap of extrapolating from a small sample in a small area.

The AKF has developed a Koala Habitat Atlas (see below) for the whole State, and as you can see, there just isn't enough habitat to support such a huge number of Koalas.

 

 

 

These overestimations by government occur Australia-wide. Protecting Koalas in South Australia is very important, but can definitely not be an 'insurance policy', nor an alternative to protecting Koalas on the East coast. Koala Populations are rapidly declining Australia-wide. A Koala Protection Act is needed to ensure the future of Koalas.

Below you can read thoughts from Dr Douglas Kerlin, AKF Chief Ecologist on the 'Great Koala Count', which is the study that the South Australian Government got their figures from.

 

 

'South Australian government figures estimate there are between 27,685 -199,723 Koalas in the Adelaide / Mt. Lofty Ranges area (mean estimate

113, 704). Compare this with the Australian Koala Foundation's (AKF) estimate: we believe there are between 12,180 and 13, 870 Koalas in South Australia. Which estimate is correct?

I would argue that there is a pretty simple reason to doubt the higher Government figure. We already know that, in 1997, 1,105 koalas were translocated to this area. Remember, Koalas in this area were hunted to extinction in the early 1900s. There were apparently no Koalas in this area prior to the 1997 translocations.

And it is basically impossible that a population of 1,105 Koalas could grow to a population of 114,000 Koalas in 15 years. The population would have to double every 2.243 years.  That is significantly higher than has ever been observed anywhere else in Australia.

The next closest estimated population doubling time would be found in island populations.  Using the island population doubling time (3.2

years) would give a population estimate of 28,500, so you can see how significant the difference is.

Why is the Government figure so high? It is hard to guess, but we would suggest the biggest issue is scaling - how they have taken numbers for small areas, and extrapolated them across the wider area.  It is a problem we see time and again, including some of the preposterous Koala population estimates that have come out of Kangaroo Island over the years.

I'll make one final point. These populations are of extremely limited value as an 'insurance policy' for the East Coast Koalas, as has been argued.  Inbreeding is a real problem. As mentioned, Koalas were hunted to extiction in the early 1900's in VIC and SA. Nearly all of the animals now occupying those States are descended from a small island population that survived the slaughter.'