Palatability mapping: a koala's eye view of spatial variation in habitat quality
Ben D. Moore,1,4 Ivan R. Lawler,2,5 Ian R. Wallis,1 Colin M. Beale,3,6 and William J. Foley1
1Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200 Australia
2School of Earth and Environmental Sciences, James Cook University of North Queensland, Douglas, Queensland 4811 Australia
3Ecology Group, Macaulay Land Use Research Institute, Aberdeen AB158QH United Kingdom
Ecologists trying to understand the value of habitat to animals must first describe the value of resources contained in the habitat to animals and, second, they must describe spatial variation in resource quality at a resolution relevant to individual animal foraging. We addressed these issues in a study of koalas (Phascolarctos cinereus) in a Eucalyptus woodland. We measured beneficial and deterrent chemical characteristics as well as the palatability of trees using a near-infrared spectroscopic model based on direct feeding experiments. Tree use by koalas was influenced by tree size and foliar quality but was also context-dependent: trees were more likely to be visited if they were surrounded by small, unpalatable trees or by large, palatable trees. Spatial autocorrelation analysis and several mapping approaches demonstrated that foliar quality is spatially structured in the woodland at a scale relevant to foraging decisions by koalas and that the spatial structure is an important component of habitat quality.
Key words: associational defense; Australian Eucalyptus woodland; formylated phloroglucinol compounds; generalized additive mixed modeling; habitat quality; koala; NIRS; patch use; Phascolarctos cinereus; plant secondary metabolites; spatial autocorrelation.