Koalas are picky eaters. There are more than 800 species of Eucalypt in the world but koalas don’t eat all of them. And of the ones they do eat, they only munch on the tips. Talk about fussy! So when it comes to feeding four Queensland Koalas at Perth Zoo, we need to make sure we have a lot of trees to choose from.
Luckily, Perth Zoo has a big supply of 14,000 trees. For the past 20 years, Perth Zoo has maintained an off-site plantation which is carefully managed to ensure a steady year-round supply of tasty Eucalypt tips.
Perth Zoo Horticulturist Kathie Mauger says the plantation began in 1991 but Perth Zoo has only been completely self-sufficient for the past five years.
“Previously, our Eucalypt leaves were supplemented with stock from Yanchep National Park,” Kathie says. “Now, we’re very pleased to get everything we need from our own plantation at Byford.”
Every two days, Perth Zoo’s leaf-cutter heads out to the plantation and cuts between 56 and 84 branches, making sure to select quality tips. While the branch might be 1.5 metres long, the koalas typically eat only 30 cm off the top. The rest is collected at the end of the day and mulched.
“To cater for their selective tastes, we grow seven types of Eucalypt, six from New South Wales and Queensland and one Western Australian species. Of course, there are no koalas in the wild in WA but the Queensland Koalas at the Zoo are partial to a bit of WA Flooded Gum.
“Each day we try to give them a different selection to vary the taste. It appears that the koalas have a favourite, Eucalyptus camaldulensis or the Red River Gum, but they can’t eat that all the time.”
Once enough branches are collected, they’re loaded into the back of a covered ute with wet hessian sacks over the top to keep them moist and fresh. They are then delivered straight to the koalas’ exhibit and stored in water buckets.
“We have to make sure the leaves retain their moisture as koalas get all the food and water they need from the Eucalypt tips. Dried leaves just won’t do.”
The Zoo’s plantation is divided into plots with different varieties grouped into lots depending on the tree’s age.
When a new tree is planted, it is left to grow for about seven years and even then it’s not ready for harvest. The trees are then cut back to stumps, a practice known as coppicing. This is done to encourage regrowth which is what the koalas prefer. It also creates a manageable harvesting height.
Twelve months later, the tree is finally ready for harvesting for koala food.
“We need to wait those 12 months as the new shoots produce a phenolic compound which makes them unpalatable to mammals like koalas and possums.
“After 12 months, the toxin fades. Leaves and branches are harvested for another three years after that before they’re cut back to the stump and the process begins again.
“We hope to get 20 to 25 years out of the trees before they stop producing good quality tips and then we dig them out and plant new ones.”
Because the plantation has been going for 20 years, the paddocks are all at various stages of growth. This ensures a constant supply. The plantation is spread over many hectares which helps guards against the impact of fire or disease.
“A water system is in place to put out fires but that’s the only time water would be used for the plantation. We rely on the winter rains to make everything grow.
“The koala food also has to be produced organically. We don’t use any artificial fertilisers or pesticides, just good quality soil and a lot of love and care by the horticultural team. I think the koalas get the best meals in the Zoo.”
