Following the 2006 decision by the federal government to not list the Koala as ‘Vulnerable’, the Australian Koala Foundation (AKF) made the decision that in order to protect the species, we needed to have confidence in just how many Koalas remained in the wild, and where those Koalas were located. This resulted in Bob’s Map (named after the past chairman of the AKF); a project with the specific aim of estimating the national Koala population. A more technical outline of the process used to generate Koala estimates is available here.
Click the images for a larger view.
Bob's Map is the result of 8 million dollars and 15 years of research and simply and powerfully illustrates the dramatic impact humans have had on the landscape, and the devastating losses the land has felt since Europeans first settled in Australia. It’s not just the trees lost over the last 225 years, but the impacts of this habitat loss on over 1,000 threatened species, on our soil and water, on our climate, and on our general quality of life.
Initially National Vegetation Information System (NVIS) Version 1.0 data was used to map potential Koala habitat on the East coast of Australia. Of the 26 NVIS classes we selected four classes containing tree species that might be suitable for use by Koalas. Vegetation mapping was initially split into regional ecosystems, and later reapportioned by federal electorate. As the Federal Government and its elected parliamentarians are the ultimate guardians of the species, it was felt appropriate to examine the issue on this basis. For a map of your local Federal electorate and how your local member scores, visit Act or Axe.
Field Data Collection
While conducting research to develop the AKF Koala Habitat Atlas (KHA), the AKF has accumulated a database of records for over 100,000 individually assessed trees from 2,000 field sites in 16 of the 30 bioregions the Koala is known to occur. At each field site, Koala habitat utilisation and tree species preferences were assessed. Combined with vegetation maps this data allows AKF researchers to estimate the amount of habitat remaining, and to rank that habitat in terms of its suitability for Koalas.
Estimating Koala Abundance
AKF has developed over 250 KHAs providing data on the amount and quality of available habitat. Additionally, we have made use of the results of a number of published studies conducted by other researchers. With this data we can model estimates of the proportion of habitat occupied by Koalas, potential Koala densities and home range sizes in each class of habitat and use this information to predict the number of Koalas in each area. The results are validated and adjusted if necessary using information provided by researchers and local community groups working in the local area.
Given the significant experience the AKF has developed in the course of collecting data from around the country, and the generally satisfactory levels of confidence gained through the validation process, we have been and will continue to further develop the methodology underpinning Bob’s Map.
In 2012 NVIS Version 4.1 became available, addressing several shortcomings in the first NVIS dataset. Data resolution was increased from one kilometre to 100 metres (one hectare) allowing capture of linear vegetation including riparian and other corridors, and the number of classes was increased from 26 to 79. Using detailed State mapping, AKF SAT sites and some expert botanical advice (thanks Derek) we have been able to assign a “eucalypt density” to 49 classes, ranging from “less than 20% (but greater than zero)” to “80 to 100%”. For the map on this page we have 4 classes, for future population modelling we will have six classes, including one for “less than 5% eucalypts” which captures, for example, brigalow vegetation with some eucalypts present. The figure below shows the difference between the two maps.