Monday, 16 December 2013

Amazing bird facts and photos

 Dr Graham Lenton brought some amazing facts and his own photographs to illustrate his talk entitled  Why Birds are so Different. These courting albatrosses have a 12' wing span that will carry them for thousands of miles across the oceans. They will dive into the top few feet of the ocean to catch fish and squid and may sit on the suface waiting for the right wind conditions but they only touch down on land for breeding.
 We are all aware of the extraordinary journeys of many birds like swifts but few of us had heard about the journey of  these bar-tailed godwits. They fly in stages up the east coast of asia from New Zealand to Russia and Alaska to breed, then fly the whole distance, some 7000 miles, back across the oceans in a week without touching land at all. Not surprisingly they arrive back looking very bedraggled and exhausted. They have made such an impression on the local people that when they set off north the bells in Christchurch are rung to celebrate their departure.

 Feet are designed for different purposes and different environments with moorhen feet designed so they can walk on the pond leaves and appear as if they are walking on water. More familiar are ducks webbed feet which are designed to give a larger surface area for paddling; but surely they are not helpful when climbing about on the roofs of houses. Graham also answered a question that is puzzling every time you watch a David Attenborough programme about the Antarctic or the film Happy Feet. Why don't penguins freeze with their feet standing on ice all the time? The answer is that they have a well-designed blood supply system that short circuits just above the foot to send most of the warm blood back to the body and just  enough warm blood round the feet to stop them freezing.
Graham also talked about the differences in bills (or beaks) for accessing different types of food. I am familiar with many differences, for example, birds of prey with their bills designed for gutting and tearing their prey and the seed eating golfinch with fine bills for foraging through the heads of teazels for tiny seeds, but I certainly didn't know that great tits' bills change in shape and size at different seasons of the year. For most of the time they are shorter and stouter for crushing seeds but in the breeding season they become finer and sharper so they can probe into tiny holes to gather the insects that they feed to their young.

Defence mechanisms were another fascinating subject and I won't forget the foul mouthed fulmar in a hurry. Be careful not to get too close to one if the chance arises as it will try to cover you in a foul smelling regurgitated mess.
These are just a few of the amazing bird facts and stories from the talk and as I am writing I remember some more. The kestrel that is really the only bird that can hover although kingfisher and barn owl make a good attempt; the hummingbird that flies backwards with its rotating wings; the fairy tern that is too lazy to make a nest, laying its egg in a tiny indentation on a branch so when the chick hatches it finds itself perched precariously on a twig. There were just too many to mention them all.
Thanks to Graham for a really interesting and enjoyable evening.

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