Frigate Bird

23 Oct 2016

You can see why scientists like to visualise dinosaurs as having had bird bones when you consider the remarkable feats of the frigate bird. Bird bones are lighter bones otherwise birds would never be able to launch themselves and remain in the air - and frigate birds have extremely light bird bones. They migrate over thousands of miles of ocean, rarely touching down for a breather, between Africa and Indonesia. They are inclined to avoid the doldrums, that equatorial region of unpredictable winds that becalmed so many sailing ships prior to the 20th century. Frigate birds are the masters of air currents. They ride on the Trade Winds in great elongated circles, round and round, moving from one cloud structure to the next, all the way across the Indian Ocean. Not in a direct line but like a rollercoaster, up and down and inside out. They glide as they have very light bodies and their big wide wings allow them to almost float rather than fly, on the slightest of breezes as well as the strongest of updraughts. A recent article in the journal Science illustrated the novel flight patterns of the frigate birds after attaching a sensor to some of them. The results were surprising as they did not fly in a straight line but in loops, making use of thermals of warm air with hardly a wing beat, flying as high as 2000 feet and on occasion sucked up to as high as 13,000 feet. Whilst dinosaurs did not fly can we say that looking at what our eyes might be telling us are great big lumbering beasts with thick tails and long necks and muscular hind legs that allowed them to move rapidly, they differ remarkably from birds such as the frigate bird - but do they have a similarity with the ostrich or emu? Bird like bones are of course a 'get out of jail' card in one way - why did they grow so big?