Koalas may be the
'pickiest' marsupials around
Koalas have evolved to feed almost exclusively on the leaves of
Eucalyptus trees, and they are highly selective when it comes to which
species and even which individual trees they visit. When the furry
leaf-eater settles on a particular tree, it relies on a number of
factors, including taste, to make its selection.
In a study published in the November issue of Ecology, a journal of
the Ecological Society of America (ESA), researchers used koala feeding
preferences to design a new method that could help ecologists and
conservationists map habitats.
Ben Moore and colleagues from the Australian National University and
the Macaulay Land Use Research Institute in Scotland collected and
analysed leaves from all the trees available to koalas in a Eucalyptus
woodland using a near-infrared spectroscopic model.
To define "palatability" in koala terms, the researchers tested
leaves on captive koalas and recorded how much they ate: They found that
the koalas ate less foliage when it contained lots of lipid-soluble
phenolic chemicals known as formylated phloroglucinol compounds (FPCs).
The researchers then tracked koala tree visits in a Eucalyptus
woodland to show that tree preferences of wild koalas could be predicted
using the taste preferences of the captive koalas.
The researchers also determined the chemical composition of the
trees' leaves and other factors such as tree size and neighborhood
quality, or how attractive each tree's neighbours were to koalas.
Specifically, koalas spend more time in large trees; however,the
individual tree they prefer depend on the taste of the leaves and the 'neighbourhood'
in which the tree is growing. Although tree size and taste are most
important to the koalas,the researchers found that trees were visited
more often if thery were surrounded by smaller, less palatable trees or
by larger more palatable trees. because koalas were attracted to these
high-quality areas.
Moor and colleaugues explained that trees surrounded by smaller
,unpalatable trees were probably more attractive by comparison.
At the other extreme, trees surrounded by other large ,pa;latable
trees were visited more frequently because koalas were attracted to
these high-quality areas
"This method uses a new technique to combine our understanding of
animal behaviour with the chemical, spatial and physical aspects of the
environment to make a map of koala habitat, as koalas see it," said
Moore. "Our approach can aid ecologists in tracking and examining the
presence or absence of animal populations in different areas -- and it
can measure plants' susceptibility to herbivory -- by determining the
quality and value of a habitat from the herbivore's point of view."
- ScienceDaily |