What's going on in our Tropical Rainforests

Skyrail Nature Diary: May 2004


Fruits, nuts and spiders, while these items may not seem to be a compatible grouping, they do provide the perfect 'what's on' guide to Australia's Tropical Rainforests this month.

Some of the rainforest's more distinctive and popular species are fruiting, including the Davidson's Plum and Candle Nut, while a not so intsy wintsy spider has climbed up into the trees and built some large and very strong webs.

The Davidson's Plum (Davidsonia pruriens), named after one of the region's pioneer sugar cane farmers, is one of the more well-known rainforest species of Tropical North Queensland, with its fruit being highly prized by local jam producers. Growing up to 12 metres high under the rainforest canopy, or four to five metres in the open, the Davidson's Plum is a distinctive rainforest species with small pink flowers and furry, pink new leaf growth.

Although its main fruiting season is usually mid to late year, the Davidson's Plums have started early this year, and the plum-shaped fruits, which are approximately 5cm in diameter, can now be found on the trees. The fruits, which are purple on the outside with bright scarlet insides, are covered by a thin layer of irritant hairs which need to be removed prior to consumption. The fruit can be eaten raw, although they are quite tart, and are more commonly used to make jams.

Meantime the Candle Nut (Aleurites moluccana), a slender, fast growing rainforest canopy tree, is now showering the forest floor with nuts, much to the delight of white tailed rats. The Candle Nut is commonly found throughout the tropical rainforests of North Queensland, the Pacific and south-east Asia and grows between 20 to 30 metres high.

Its large, globular brown fruits contain between three to five seeds, which can not only be eaten, but also used as a fuel source to help light fires, or keep fires burning during rainfalls. These seeds are a favourite food for the rainforest's white tailed rats, and are also suitable for human consumption if prepared properly. However, if they are not prepared correctly they can cause stomach upsets, so eating them is not recommended.

There are many species of spiders which call Australia's Tropical Rainforests home, but one of the most visible this month is the Golden Orb (Nephila maculata), whose webs are appearing in many trees.

The Golden Orb produces large, very strong webs, which generally measure approximately one metre across and are strategically positioned in 'fly-ways' between trees. These webs are so strong that if you walk into them you will actually feel the resistance, and they are capable of catching and stopping small birds.

The Golden Orbs' webs started appearing in April , and are easily visible thanks to the presence of the very large female Golden Orb in the middle of the web (they can have a leg scan of over 25 centimetres!). These spiders are reproducing at the moment, and if you look closely at a web you will see the smaller males around the edges, they are about one sixth the size of the females and are generally a dull black or brown. The male Golden Orb dies once mating is complete, while the female dies shortly after laying her eggs in a sac on the web.

Australia's Tropical Rainforests are home to an amazing diversity of plant and animal life, and are the oldest continually surviving rainforests on earth. Dating back more than 100 million years, these rainforests used to cover the entire Australian continent, but today are only found in a small coastal stretch between Cooktown and Townsville.

The best way to see the rainforest is on Skyrail Rainforest Cableway.