A monthly column by Rachel Shaw of Lincolnshire Wildlife Trust

Bar-tailed Godwits ANL-140110-101038001
Bar-tailed Godwits ANL-140110-101038001
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Though when the sun shines butterflies and bees are still on the wing, there is now a chill in the early morning air and enough foilage has fallen from the lime trees lining my street that I can kick the leaves.

Surely a sign the season has changed. With the passing of the autumn equinox on September 23, our days are now shorter than our nights. Autumn has arrived.

Swifts with their distinctive screaming calls that give the summer its soundtrack are long gone. Perhaps amongst the last swifts to leave Lincolnshire’s shores and head back to their wintering grounds in Africa were 15 reported flying south across Gibraltar Point National Nature Reserve on August 28.

On the same day, 1,000 swallows were counted all heading south, along with a handful of blackcaps, chiffchaffs, pied flycatchers and spotted flycatchers.

With the departure of these summer favourites comes the arrival of the winter birds, who have summered in Scandinavia and Russia.

Siskin, bramblings and redpolls have arrived. These will soon be joined by fieldfares, redwings and blackbirds. It may be a surprise that such a familiar bird as a blackbird also migrates. Our resident populations of birds including blackbirds, chaffinches and robins are joined by birds from the continent where the winters can be harsher.

Sometimes the migrating birds arrive in immense numbers known as ‘a fall’. Many birds migrate on clear nights, using the stars to navigate. A sudden change in the weather such as a blanket of mist can disorientate the birds, causing them to land for a number of days. Availability of food is also a factor. A scarcity of food in the place they spent the summer will cause larger numbers to migrate.

There are some staggeringly large numbers of birds arriving at Gibraltar Point. In recent weeks there have been reports of 3,657 bar-tailed godwit, 1,986 grey plover, 3,115 sanderling, 10,274 dunlin and 70,000 knot. These are coastal wading birds. They will spend the winter on the mudflats and sandflats feeding on worms and other invertebrates.

On the highest of tides, when they are pushed off these feeding grounds by the incoming tides, they form vast flocks of birds. Twisting and wheeling in the sky in great clouds, it is one of the most spectacular sights of the natural world. Starlings also form vast flocks in the late autumn and winter. Poetically called murmurations, they provide a mesmerising acrobatic display.