Abstract
Understanding the ability of koalas to respond to changes in their environment is critical for conservation of the species and their habitat. We monitored the behavioural response of koalas to declining food resources in manna gum (Eucalyptus viminalis) woodland at Cape Otway, Victoria, Australia, from September 2011 to November 2013. Over this period, koala population density increased from 10.1 to 18.4 koalas.ha-1. As a result of the high browsing pressure of this population, manna gum canopy condition declined with 71.4% manna gum being completely or highly defoliated in September 2013. Despite declining food resources, radio collared koalas (N = 30) exhibited high fidelity to small ranges (0.4–1.2 ha). When trees became severely defoliated in September 2013, koalas moved relatively short distances from their former ranges (mean predicted change in range centroid = 144 m) and remained in areas of 0.9 to 1.0 ha. This was despite the high connectivity of most manna gum woodland, and close proximity of the study site (< 3 km) to the contiguous mixed forest of the Great Otway National Park. Limited movement had catastrophic consequences for koalas with 71% (15/21) of radio collared koalas dying from starvation or being euthanased due to their poor condition between September and November 2013.
Highlights
Conservation of a species relies on an understanding of how it responds to habitat change or loss [1,2,3]
The study was undertaken from September 2011 to November 2013 in manna gum woodland at Cape Otway (38°50’06”S, 143°30’25”E), Victoria, Australia (Fig 1)
Koala populations increased each year from a mean of 10.1 koalas.ha-1 in 2011 to 18.4 koalas.ha-1 in 2013 (Table 1)
Summary
Conservation of a species relies on an understanding of how it responds to habitat change or loss [1,2,3] This is important for species that have highly specialised dietary or nesting/roosting requirements and limited ability to adapt to modified habitats. Where such species occur in landscapes subject to a change in resource distribution and availability, survival of individuals relies on their ability to relocate to new habitats [4]. This may be limited by landscape factors such as the availability and distance to suitable habitat patches, and the PLOS ONE | DOI:10.1371/journal.pone.0144348. Most gliders only moved as their nest trees were being felled, and failed to relocate successfully to neighbouring habitat
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