It isn’t just in spring and autumn that birds are on the move. Winter sees many species flying long distances because of changes in the weather or lack of a specific food.

At the time of writing, redwings are pouring into gardens and green spaces in central London, including Hampstead Heath. Many have been in the country since autumn, having crossed the North sea in their thousands at night.

In late October and early November you can hear flocks making their piercingly high contact call, especially on clear nights with an east wind behind them.

In daylight, they are easily distinguished by the white stripe over the eye and a red patch under the wing.

Newly arrived birds, prefer the safety, and abundant berries of native hawthorn, rowan and holly. Then, as they filter through Norfolk and Suffolk, they join blackbirds and song thrushes on the ground, feasting on fallen apples in orchards and earthworms in ploughed fields.

But recent snow and ice, has cut off these supplies, and they are forced to seek food, and shelter, in the warmer cities. Here, the diet might include berries of familiar “garden” shrubs, such as mahonia, pyracantha and cotoneaster.

Once in the cities, they tend to stay - unless we get more snow and they move on again, usually south west towards the milder coast, but sometimes across the channel to France or Spain. If you’re lucky, you may see another thrush accompanying the redwings.

Fieldfares – slightly larger than blackbirds with a distinctive “shook, shook shook” call – also emanate from Scandinavia, and can be found in similar habitat to redwings, but favour open areas, rather than woodland edges.

They have a slower, undulating flight and are a little more shy. Over Parliament Hill, you can almost guarantee some sizable flocks after a fall of snow. Under such conditions birds lose their wariness and can even be found in front gardens, desperate for some energy boosting fruit or berries.

Kingfishers are residents on Hampstead Heath, occasionally breeding. They are often spotted perched on an overhanging branch, or on a makeshift post, gazing down into the water, where their prey swims or wriggles.

They are surprisingly difficult to relocate once they have moved, the bright colours somehow disappearing. Their diet consists not only of small fish, but tadpoles and aquatic insects. Sometimes I get to point out a perched bird – the Sanctuary pond is a good place – although you are just as likely to see a bird on the move – a flash of blue on a small bird whirring inches above the surface.

Icy weather triggers a move out to larger lakes, or even the coast, where they will switch to feeding in the brackish water of an estuary. Extensive cold though, can really hammer their numbers, as young birds have a high mortality and even breeding adults rarely survive more than a few seasons. Kingfishers must eat their own body weight every day, so several blank days can be life threatening.

Until quite recently, blackcaps, small migrant warblers, were strictly summer migrants to Hampstead Heath. They would arrive in April, sing their fluty song, have two or three broods then head back south in September.

But now the situation is more complex. A combination of global warming and a significant rise in bird feeders has tempted a number of them to stay – not just into autumn but through winter.

Birds breeding in central Europe, that would formerly have passed through London on the way to winter in Spain or Africa, are taking advantage of the kinder climate, and an increase in food, and shortening their migration.

This gives these individuals a great advantage over those still migrating from different areas. Not only are they in better condition by March, but they bag the choice nesting sites. Whether this change will spread to other populations is anyone’s guess. But for now the Heath has an abundance of blackcaps, from near and far.

Encourage more birds into your garden by planting a selection of shrubs, including some natives such as ivy and honeysuckle. Certain trees and shrubs will attract certain birds. If you want blackbirds (and who wouldn’t?) Plant a myrtle.

If you want to attract blackcaps, plant blackberries or a big vine. If it’s goldfinches you’re after sow some teasel try too, to have water available, all year round. Ideally a small pond - that could also attract frogs, but a big saucer will bring results. The bird list will really shoot up.

  • Peter Mantle is from the Heath & Hampstead Society.