Evolution of Flight

Kings of the Skies and Other Aerial Acrobats

Birds, bats and insects show how it is done: with muscle power, low weight and technique, they take to the air. Insects were the first to do so, 350 million years ago; pterosaurs followed around 230 million years ago, birds 150 million years ago and bats 50 million years ago. With their streamlined bodies, air-filled bones and plumage that is both strong and light, birds are especially skilful fliers. In fact, only their weight sets limits: at 19 kg, the kori bustard, which lives in Africa, is the heaviest bird capable of flight.

World Champion of Gliding Flight

Common swifts are long-distance migrants, travelling several thousand kilometres. In Tyrol they are rare: around 500 to 1,000 breeding pairs live here in summer. They are mostly found near settlements in the main valleys. Their nesting sites lie at an average altitude of 770 metres above sea level, and on cliffs at up to 2,400 metres.

Common swifts can remain in the air for up to ten months, almost without interruption. Each year they cover 190,000 km, and their top speed is 200 km/h. Only the peregrine falcon is faster, reaching 250 km/h — and even 320 km/h in a dive.

Common swift,
Apus apus

A Majestic Bird That Stays Grounded

Western capercaillies are resident birds, staying in the same region all year round. They belong to the grouse family and occur throughout Tyrol. Around 1,700 to 2,300 individuals have their breeding sites in mountain forests rich in old trees. You may encounter this majestic bird in the forest and on clearings — for one very specific reason: at 4 to 5 kg, Europe’s largest galliform bird is a rather poor flyer.

Western capercaillies,
Tetrao urogallus

Forelimb Skeletons Compared

The human arm skeleton consists of the upper arm bone, ulna, radius, carpal bones, metacarpals and finger bones. This structure allows us to grasp well. In pterosaurs, birds and bats, the corresponding bones evolved into the internal framework of the wings.