Saturday 9 February 2008

An ideal location for a vacation


You may not realise it but your garden provides a winter retreat for a whole bunch of foreign visitors. In amongst your resident garden birds will be those that have arrived here from as far afield as Norway, Iceland or even Russia. The thing about these avian ‘tourists’ is that many of them go completely unnoticed. While visiting Bramblings, Waxwings and Fieldfares might stand out from the crowd because they don’t breed here, visiting Chaffinches, Greenfinches, Blackbirds and Robins don’t look any different from their resident counterparts. We only know that they are here because scientists across Europe regularly fit small metal rings to birds. In time, some of the birds fitted with rings are caught elsewhere by bird ringers; others fall victim to pet cats, fly into windows or collide with traffic. If somebody finds the bird, notices the ring and then contacts the address stamped into the ring, then the researchers can work out where the bird has gone and over what time period.

Thanks to the efforts of these scientists it has been possible to estimate, for example, that a minimum 12% of the Blackbirds in Britain outside of the breeding season actually come from overseas. Equally sizeable populations of various finches and other thrushes also winter here, collectively hinting at what an attractive destination a British garden makes. So why should Britain be so good in the winter? It may not seem as pleasant here as somewhere further south, for example the Mediterranean coast of Spain. However, Britain is actually surprisingly mild for its latitude during winter, warmed by the Gulf Stream and this means that birds can overwinter here in relative comfort. They are also closer to their breeding grounds than they would be if they had migrated further south. This is also advantageous because they do not have as far to go on the return leg in spring, thereby reducing the energy stores needed to get them home.

Of course, another reason why our gardens are so attractive is that they are often stocked full of food, thanks to our love of birds and willingness to feed them. Some of the visiting birds will have moved here over several months, following natural fruit and seed supplies and only reaching our shores once these stocks have run out. Not only that, but many gardens have conifers in which these birds can roost overnight, water which they can drink or in which they can bathe. So take a look out of your window and cast your eye over the Blackbirds fighting over apples on your lawn or the Starlings squabbling over your bird cake. Are these local birds or do some of them bicker with a continental accent?

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