In nature, everything is connected. But some of the affinities between koalas and other animals might surprise you!
Honeyeaters, like this Eastern Spinebill, pollinate trees. Without honeyeaters, new trees will struggle to grow. No trees = no koalas.
If Flame Robins didn’t eat insects, plants would suffer from insect overpopulation. Insects eat the leaves of many plants, eucalyptus included. Too many insects = no leaves on trees for koalas to eat.
Even butterflies are important to koalas. Butterflies, like this Common Brown, pollinate native plants when they search for nectar to drink. Unlike bees, who pollinate a small area very effectively, butterflies can carry pollen large distances, which means they can bring new plants to an area and ensure an even spread of a diversity of plants. Plant diversity at the ground level helps other animals like wallabies thrive.
Caterpillars, the babies of butterflies, eat plants. The caterpillar of the Common Brown eats grasses like Kangaroo Grass (Themeda triandra), which has a tendency to become too dominant in an area if not managed. Aboriginal People managed kangaroo grass with regular small fires, but now that is not happening, we are lucky to have Common Brown caterpillars!
Macropods (kangaroos, wallabies) make tracks through thick undergrowth as they search for food and water. When the undergrowth is thick, koalas use the tracks of kangaroos and wallabies to move around from tree to tree every day. If there are no tracks through thick undergrowth, a koala is in danger of predation by dogs, and they find it much harder to push through. Too much energy expended means a koala has less energy to breed.
Grass-seed eaters, like Long-billed Corellas, spread the seeds of grasses and help control weeds like Onion Grass. Grassy woodlands are perfect habitat for koalas, providing easy movement from tree to tree.
Koalas also benefit other species. Black-chinned Honeyeaters are a threatened small bird. They take fur from koalas to line their nests. Without koalas, who will the Black-chinned Honeyeaters get fur from? Wallabies don’t stay still long enough, possums are only out at night. Will baby Black-chinned Honeyeaters get too cold in their nests and die?
Some creatures, like this Painted Honeyeater, have almost disappeared from koala habitat. Could this be why koalas are declining? We just don’t know.
People often ask us why koalas are declining, even in National Parks. Truth is, no-one is really sure. Every region has different challenges, but overall, koalas are declining too rapidly for their long-term survival.
We don’t know the answer to koala decline, but we do know this: everything is connected. When Grey-crowned Babblers disappeared from the You Yangs, did that affect koalas? Maybe only slightly. When Tasmanian Pademelons, Eastern Barred Bandicoots, Brush-tailed Rock-wallabies and Dingoes disappeared did that affect koalas? Slightly+slightly+slightly+slightly = a lot.
Fact is, we have lost insect, bird, reptile and plant species that koalas rely on from koala forests, yet we still expect koalas to breed well (but not too much) and live long healthy lives. It is amazing that they are surviving at all.