Koala Habitat & Population Assessment

Biolink is unique in having both specialist in-house knowledge and the methodologies to address the complex issues of identifying and mapping koala habitat, as well as investigating and modeling the distribution of free-ranging koala populations over large geographic areas. Biolink staff also have expertise in the preparation of site-specific and shire-wide koala plans of management, and are capable of undertaking health assessments and Population Viability Analysis for koala populations, as well as investigating ecological history relevant to regional study areas.

Koala Habitat Mapping

National concern about koalas now manifests itself in the National Koala Conservation and Management Strategy 2009 - 2014 (NRMMC 2009). As evidenced by a recent review, the former National Koala Conservation Strategy (now replaced by the above) didn't really do much except present a bunch of motherhood statements about koala conservation and management that have little (if any) impact on the ground; this is the Government's way of dealing with the politics of koala conservation. There is also an approved recovery plan for koalas in NSW. Koala conservation and management efforts are further guided in New South Wales by State Environmental Planning Policy No. 44 - (Koala Habitat Protection), while in Queensland (where koalas are listed as a vulnerable species in the south east Queensland bioregion) it's the Nature Conservation (Koala) Conservation Plan and Management Program 2006 - 2016. What's especially interesting about these last two documents (given that they both share common objectives) is the extent to which they differ in their respective approaches rather than what they share. Regardless,both approaches require some form of habitat assessment/categorisation/mapping to be carried out. That's where we come in...

Based on a sampling tool called the Spot Assessment Technique (SAT) we have developed an unbiased and systematic approach to the matter of objectively assessing koala habitat. Called Regularised Grid-based Spot Assessment Technique (RG-bSAT) sampling, it enables assessment over large, heterogeneous landscapes. The data obtained allows us to determine several things including localised food tree preferences and even koala population density (and hence population size), while also providing key information on exactly where koala populations are located across the landscape, the boundaries of which we can identify using spatial analysis components of GIS software.

How reliable is the modelling?

Over the last seven years RG-bSAT has been applied in various areas along the eastern seaboard of Australia from Raymond Island in Victoria, the south-east forests of NSW to the Gold Coast in south-eastern Queensland. On average, our modelling captures 85 - 90% of contemporary koala records (which is quite acceptable given that a proportion of all observations will always be attributable to transient animals). Most importantly though, the boundaries which result from our modelling invariably capture 100% of breeding females; this is a significant outcome and allows us to be confident that our approach clearly delineates the most important habitat areas.

The best test of what we do arguably lies in the realm of scientific peer-review. To this end we have recently submitted the details of our approach  for publication (Phillips, S., Hopkins, M., and Warnken, J. Splines in the sand: modelling population structure across the landscape to provide greater planning certainty for an arboreal marsupial (Koala Phascolarctos cinereus Goldfuss)).

Why is it also important to do population and/or health assessments?

An understanding of the distribution of age classes within a given population is fundamental for effective conservation and management planning. Ideally, what we look for is a population with age classes that are approximately normally distributed (i.e. the majority of a individuals in a given population belonging to the middle-aged tooth wear classes). If the age-class distribution of a given population is skewed to the left (of normal), then it tells us that the population is mostly comprised of older animals and recruitment into the population is probably a key issue. This leads us to not only ask why, but then to develop management actions and/or guidelines that can effectively redress the imbalance. Conversely, if the age-class data is skewed to the right, it tells us that the population is largely comprised of young animals and likely to be in a positive growth mode.

How do you tell how old a koala is?

We look in their mouths and in particular at the amount of wear evident on the pre-molar and molar teeth.

How do you catch a wild koala?

Unlike Government agencies in Victoria and South Australia, we won't use nooses to capture koalas because we consider it to be unethical, unnecessary and traumatic for the animal. Instead we use either a flagging technique (cloth attached to one or more extendable poles) to encourage a descent to the ground, or alternatively, a custom designed koala trap. Both are very effective techniques and allow us to gather meaningful data in a manner that is both time and cost effective, but which also causes minimum stress.