You are absolutely correct. The trees, while spectacular, are all hotwired just below the crown. By zooming in on the original photo it is also possible to make out some wire/plastic sheets covering at least a couple of the trees.
I was here on a blistering hot day — the sun normally doesn't bother me but something about the lack of cover and the reflection from the sun forced me to move along from the baboon exhibit. So now I finally get to see it in it's entirety — thanks for the great photo! Looks like they have an incredible amount of land to move around in; do you know how many they have at the Melbourne Zoo?