Birds - General Information

Aves - a class of their own

While the Wet Tropics region is home to a quarter of Australia's frogs or a little over a third of the country's freshwater fish, it is home to nearly half of Australia's birds which means that the region harbours more than 370 bird species.

Like the plants, the Class Aves (the birds) has evolved into a wide variety of forms, some much older in the planet's evolutionary time scale than others. Because of the variety of habitat types, altitudes and food resources available in the Wet Tropics (it's not all rainforest), we can enjoy seeing the greatest number of birds in Australia. Some of the best places for birdwatching are ecotones - areas where two habitat types meet.

When trying to reconcile the distribution of modern birds and the former existence and breakup of the southern supercontinent Gondwana, some controversies cannot be avoided. There is still a healthy scientific debate raging as to WHERE birds originated, WHAT they evolved from and WHY they evolved at all.

Presently, the first bird is still credited as being Archaeopteryx and it is the first fossil unearthed with clearly defined feathers. Archaeopteryx is 145 million years old which means it is from the Jurassic Period - the time of the greatest dinosaur diversity. However, some other fossils have been found in China, Patagonia and Madagascar which also have features which make them bird-like dinosaurs or dinosaur-like birds. These fossils have been dated from 130, 88 and 80 million years ago, respectively. To cut a long story short, the prevailing view supports the concept that birds evolved from dinosaurs. Since Archeopteryx is the oldest of these and was found in what is now southern Germany (the next oldest is from China), it supports the idea that birds evolved in the northern hemisphere first and spread to Gondwana.

The oldest known bird fossils found in Australia have come from the Koonwarra fish beds near Melbourne and are dated from 110-115 million years ago. Unfortunately, it might be difficult to construct a neat and tidy sequence of modern bird evolution in Australia. At the time in earth's history when birds were becoming more diverse (the Tertiary period), the physical conditions which create good fossils were biased in favour of aquatic birds. We do know, however, that the oldest birds were the flightless species which makes our emu and cassowary Australia's oldest surviving bird species.