Birds and Weather
The weather patterns that occur across Britain are complex, and being isolated from the land mass of the continent and surrounded by the sea, the weather in the north of Britain is often quite different to the weather in the south.
Throughout the year birders are avid viewers of the daily weather forecasts and while for example in October east coast birders are waiting, if not praying, for easterly winds then there counterparts in the west are wishing for strong westerly airflows produced by fast moving tropical storms that began life off the eastern seaboard of America. A basic understanding of how weather systems affect birds and the patterns of bird migration is quite fundamental in choosing the site you visit on a particular day and the species you look for. It would not be a good use of time to sea-watch for eight hours if there was a strong offshore wind on a cloudless day. You would see a few birds but time would be better spent walking sheltered sunny spots that may hold a few birds.
The same weather in different parts of Britain will produce differing birds. Strong south westerly or north westerly winds during August and September will in the south west of Cornwall and south west Ireland often result in good numbers of seabirds passing close inshore. These will be species that are rarely seen in calm or reverse weather and include Cory's & Great Shearwater and Sabine's Gull. Strong south westerly winds along the east coast of Britain would normally produce few birds during the same period. However a strong north westerly and north east winds can produce good sea watching along north facing coast or headlands such as Norfolk and parts of Yorkshire such as Flamborough Head.
The general rule regarding passerines is that onshore winds tend to help produce occurrences of both common migrants and scarce birds during the peak migration times. The south coast can be excellent in spring with soft south and south easterly winds that help push migrants from the continent across the English Channel. South easterly winds during the spring are good for the whole of east coast Britain and it is this wind that is responsible for the occurrence of eastern European and Scandinavian birds from Kent to Shetland during March - November.
Cold weather movements during this month are often not as dramatic as during January though can still involve many species and in quite large numbers. Very cold weather during January that has forced birds to move can continue in to February as in 1963 when large numbers of grebes, diving ducks and raptors continued to arrive in eastern England. Cold weather during February, when food availability is very low, can produce interesting records of birds visiting gardens such as Water Rail (right) and Woodcock.
This month is a good month to search through the flocks of geese, ducks and gulls as these groups of birds often become nomadic looking for food and shelter. Sea watching is normally poor during this month with few sea birds seen and little passage. Though once again cold weather with onshore winds can produce movements of wildfowl and waders.
Spring migration for several species begins during February and though not always obvious certain species such as Skylarks & Meadow Pipits begin their return migration in some numbers. These birds will have wintered in southern England or northern France and Holland and are making the first tentative movements northwards. This early migration can include numbers of species in particular Stonechat and Linnet. Light south & south-east winds with rising temperatures often encourage these light movements.
A good indicator of birds heading northwards during early spring can be seen from sighting along the western coast of France.
Rare & scarce spring migrants often occur in late February along the south coast of Britain as well as the east coast. The following species have all be recorded as migrants in Britain during the month of February; Night Heron, Ballion's Crake and Red-rumped Swallow and Serin.
Paul Laurie runs birdwatching tours in Norfolk through his Bird ID Company. Paul is also currently writing a book on birdwatching and this article is taken from part of a chapter on weather - we will bring you full details of the book when it is published.