Bird Migration - A Natural Miracle
BIRDS
Part One: Explorers and Pioneers by William Bowell The journeys undertaken by birds on their migration from their summer breeding homes to their wintering grounds are incredible. As the nights get longer in October, migration is well underway for birds and our small island is a brilliant place to witness this natural miracle. Why do birds migrate? The urge to migrate to warmer climes isn’t because birds are thrill-seeking sun lovers. Migration is a dangerous undertaking. Goldcrests weigh the same as a 20 pence piece yet fearlessly set out across the North Sea to our shores this month. These are the smallest birds to be recorded in Britain and are a common breeder here, but in October numbers swell as Continental birds arrive, with some remaining and some leaving for southern mainland Europe. On their journey over the sea they will encounter bad weather, predators and almost certain exhaustion. They can only land if they are lucky enough to find a boat or oil rig. The risk is high but the will is stronger. The two main factors that compel birds to migrate are food and weather. Usually the two are connected. A breeding location in the far north can be inhospitable in the winter which will make finding food hard if not impossible. Birds also migrate to find new food sources as a way to preserve their feeding grounds for the next year. A ‘Fall’ of birds Imagine you are standing on the east coast in October. The wind is a stiff north-easterly and there is a threat of rain in the air. Hundreds of miles away in Scandinavia, though, the Norwegian coastline is set fine and clear after a week of westerly winds and rain. This is exactly the set of conditions that, as a birder, I crave. Great White & Little Egret. Little Egret first bred in Britain in 1996 and now is a common sight around the Deepings. Great White Egret first bred in Britain this decade and is now annual in the Deepings. This was taken on Deeping Highbank.
Pied Flycatcher. These small passerines are regularly associated with ‘falls’ on the east coast as they fly down to Africa from their northern breeding grounds.
Why? Because these are also the conditions which will bring millions of ‘common’ birds over to our shores. I have witnessed amazing ‘falls’ on the east coast before, from tens of thousands of goldcrests in Yorkshire to thousands of blackbirds and other thrushes on the north Norfolk coast. Many of these birds are just so exhausted that they show no fear of humans as all they want to do is feed. Many will perish but those who don’t, once they are strong enough once again, will continue to thrive. Other birds that have spent the summer here will also be the move. Swifts, birds which only land to breed (even sleeping on the wing) have long gone, having spent just four or so months in Britain. Swallows and martins, if they haven’t already, will be gathering on wires, having raised several broods of the next generation, getting ready to show them the way to Africa– a migration which could see them cross the barren landscape of the Sahara Desert. The Pioneers and Lost Souls Not all birds that reach our shores mean to get here. These could be blown off course, deranged or lost. These vagrants can also be at the very sharp end of colonising and the changing of a species range. As our climate in Britain gets warmer some birds are moving in from the south, whilst others are finding it too hot to handle and retreating north. continued >
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