Sunday, 17 January 2010

Making the best of bad weather

Birds have a range of behaviours to cope with the cold. Many - Swallows, Cuckoo, many warblers - avoid it altogether by migrating to warmer latitudes well ahead of winter, these are birds exploiting resources that are virtually non-existing in the winter such as caterpillars or flying insects. Others undergo more regional migrations, often depending on the local conditions. Here, surprisingly, there are many British species, which move south to the continent, and at the same time come to the UK from colder areas like Fennoscandia, these would include the Robin or the Blackcap. Yet another group of species simply change their habitat preferences. Some species that are found in mountain areas move down to the plains in the winter, species that feed on freshwater lakes and ponds in the summer move to the coast, where water does not freeze in the winter (Grebes and Kingfishers do this). There are a fourth group of species which change their food habits with cold weather. The Blackbird and other thrushes switch to feeding on berries when the ground is too hard to hunt for earthworms. I probably haven't exhausted the options and several of them are not mutually exclusive. For example, the Swift, a summer migrant from Africa, also undergoes substantial regional migrations in avoidance of poor weather. In addition, some of these options are only taken depending on the local conditions. The Waxwing's irruptions, when birds normally inhabitants of northern Europe, reach the UK and western Europe, happen in response to poor berry crops in the rowan of their native forests, and then to happen at irregular intervals. The last one of such invasions happened during the winter of 2008-2009.
  In the last few days, I have noticed couple of species which I don't see very often within the city have become more common. One of them is the Pied Wagtail, the other the Redwing. The first one belong to the  habitat switchers, the Pied Wagtail is most often found in gardens and towns during the winter. With its constant tail bobbing and its frantic running and direction-changing motion in chase of minute insects and bugs, to get a decent photo in the gloomy dark days we've had lately is a challenge. The Redwings, which migrate into the UK in the winter from northern Europe, feed on grassy areas - or berries - in loose flocks, they are quite wary and the photos are also not good.

Two Redwings

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