The secret life of garden birds in winter

Rather than hibernate in winter, birds employ various tactics to survive. Some migrate, others eat more and move less to conserve energy, and some roost together to keep warm. Find out below what your garden birds are doing this season.

How do garden birds survive in winter?

Migration

We all know that swifts and swallows migrate from the UK to Africa for winter, but did you know that robins and blackbirds migrate too? Your summer resident robin may fly south to, say, France, while the winter robin in your garden may spend summer in a similar garden in Sheffield or some other northern region. Never assume that your garden robin is the same one all-year round, you could have a summer one and a winter one.

Communal roosting

Keep an eye on your bird boxes at dusk: some birds roost together to keep warm. Bird such as wrens may squeeze themselves into one bird box to stay warm on cold nights – the record is from 1969, when 61 wrens were found roosting together in a nest box in Norfolk.

Fluffing feathers

Birds may look fat on cold days, but they're actually all fluffed up – they use their feathers to trap air, which insulates them against the cold. Birds with clean feathers are able to insulate themselves better than those with dirty feathers, so keep your bird baths topped up with fresh water so birds can keep themselves as clean and insulated as possible.

Shivering

Birds use a lot of calories to shiver, which helps to keep them warm. They eat a lot during the day to gain fat reserves to give them the energy they need to shiver at night, and benefit from calorie-rich foods such as sunflower seeds. However, to save energy throughout the day, birds are less mobile, so will fly less to conserve the calories they need for shivering.

Communal feeding

With natural food in short supply, some species form winter flocks to search for food together. Look for roving flocks of mixed species such as blue tits and great tits, along with goldcrests and firecrests. You'll see them scouring trees and shrubs for insects, spiders, eggs and grubs.

Defending territories

Some birds, like robins and wrens, will establish winter territories, which they defend throughout the season. Studies have shown that those who defend territories are more likely to survive winter, presumably as they defend the food sources within those territories. Look out for birds chasing each other out of your garden. if you have a holly tree, is there a song thrush in it? They can guard the berries throughout winter to stop other birds eating them.

Courtship

After the winter solstice and the days start drawing out, keep an eye on the robins and great tits in your garden. You may spot courtship behaviour from robins – the male bringing the female food, for example, or the pair looking for nest sites together. Similarly, great tits may start prospecting for nest sites. Look out for them checking out nest boxes while also preventing other birds, such as blue tits, from doing so.

What do birds eat in winter?

Birds eat berries, crab apples, seeds and insects, spiders and even eggs, which they glean from leaves, stems and the bark of trees.

To help birds in your garden, grow as many berrying trees and shrubs as possible, including hawthorn, rowan, roses (that produce rose hips), apples, holly and ivy. Grow seeding plants such as teasels, sunflowers, thistles and ornamental grasses like miscanthus. It's also worth letting seeds remain on herbaceous plants in your border – even seeds from lavender will be taken. Elsewhere in the garden, let leaves pile up and don't be too tidy – these small habitat areas will provide shelter for grubs, which birds such as blackbirds will pick through.

Should I provide supplementary food for birds?

Feeding garden birds certainly helps them survive harsh winters, but studies have shown that this can also increase risk of disease transmission such as avian pox and trichonomosis, and also give some birds an advantage over others (for example great tits, which increased by 77 per cent from 1967 to 2023, compared to marsh tits, which declined by 81 per cent in the same period). Improving garden habitats is therefore the main thing to do to help garden birds, as it enables them to feed naturally, which reduces risk of disease transmission while also reducing unfair advantage.

If you do provide supplementary food for birds, make sure you clean your feeders weekly and buy food that's been certified pesticide-free.