Nature

Our birdlife this winter

During the winter months we all look forward to spring and the sight of the first swallow. ‘Our’ swallows are now known to winter in South Africa, nearly 10,000 km (6000 miles) away, although in Gilbert White’s day (1720-1793) they were thought to overwinter in the mud of ponds! Their migration journey includes a crossing of the 2000-mile wide Sahara Desert. The change to milder winters over the last 40-50 years has meant that some flowers are in bloom almost all the year round. A few migrant birds have altered their migration pattern and some remain in Britain through the winter. There are now far more blackcaps and chiffchaffs overwintering in suburban gardens and coastal sites, and some gardens may host several blackcaps during winter. Even small numbers of swallows are now spending the winter in coastal areas of Cornwall.

Flocks of redwings and fieldfares are often seen in the countryside from autumn to spring, feeding on berries and other food. In very cold weather they even come into gardens. However, there was an almost total failure of rowan berries across Scandinavia in autumn this year. Probably as a result of this berry shortage, easterly winds at the end of October resulted in a huge arrival of winter thrushes on the east coast. Several locations recorded thousands of redwings, with 33,000 over Flamborough and an amazing 122,000 counted over Crosby Marine Park in Lancashire, together with 19,000 fieldfares. In October, whilst staying on Lundy in the Bristol Channel, I witnessed an amazing passage of thrushes, mainly fieldfares, over several days, including one day when over 4000 fieldfares were counted, with fewer redwings and ring ouzels. Fieldfares and redwings breed from Scandinavia right across to eastern Russia. They feed on hawthorn, holly berries, and rosehips; when feeding on the ground they take worms, snails, beetle larvae and other invertebrates.

As a result of this year’s outbreak of avian influenza, many seabird colonies across Britain and Ireland have been devastated, with many birds dying. This has affected a variety of seabirds, with gannets, terns and skuas badly affected. Apparently the virus can survive for a year or more and there is great concern that it may continue to affect seabird colonies next year. The virus is probably spread through wild birds coming into contact with infected chickens, and then migrating to another country.

Greenfinch numbers have declined over the last decade due to trichomonosis, which affects their lungs. Recent research has now shown that chaffinches, as well as greenfinches, can also be infected with trichomonosis. Since birds visit garden feeding stations on a daily basis, it is very important to clean out the feeders regularly to avoid spreading disease. Don’t forget to provide water for the birds to bathe in; this helps to keep their plumage in good condition. Even a small bird bath is useful. If you get frequent visits from a sparrowhawk intent on his breakfast, place the bird feeders close to a hedge or thick bush so that the birds have somewhere to hide!

Anthony John