This month, as the days get shorter and the weather colder, I’m looking at how birds prepare for the winter season ahead – and what we can do to help them!

Winter is a tough time for birds – especially the smaller species that visit our backyards and gardens, and which we enjoy seeing on our Birdfy feeder cameras. As the nights draw in, the hours available for them to feed get shorter and shorter. Meanwhile, the weather is also getting colder – often dropping below freezing in some northern locations, though in southern Britain and the southern states of the USA it may still be quite mild, even warm.

So what are the problems bird face during the cold winter months, what adaptations have they evolved to cope, and what can we do to ensure that they do survive to breed the following spring?

Birdfy in Winter

  1. The dangers of winter

Bird face three major problems in winter:

  • A shortage of time to feed
  • A problem getting access to enough food
  • How to cope with very cold temperatures, especially at nighy 

A typical small bird visiting your Birdfy camera feeder, such as a Blue Tit in the UK or Black-capped Chickadee in the USA and Canada, needs to eat between one-third and one-half of its body weight every single day, just to get enough energy to survive.

Think about it: that’s the equivalent of a 140-pound (10 stone) human being eating from 50 to 70 pounds of food a day – or between 100 and 140 Big Macs (other fast-food burgers are available!)

In late December, around the time of the winter solstice, there is only an average of about eight hours of daylight: more the further south you go, but a lot less in the north. For example, the Shetland Isles in Scotland, Hudson Bay in Canada and in parts of Alaska, all places at a latitude of 60 degrees north, the gap between sunrise and sunset falls to less than six hours.

Birds in Winter
That is why, on midwinter days, birds are active from dawn to dusk, with just one thing on their minds – where can I get food? Research in the UK has shown that on average a small bird must forage for 85% of the available hours of daylight if they are to survive the night.

If it snows heavily, covering the ground, or frost and ice forms on surfaces such as the branches and twigs of trees, finding food becomes even trickier.

And during the long winter nights, temperatures can drop well below freezing, which means that small birds struggle to stay warm enough to survive until the following morning, when must start to search for food again.
 

  1. How birds cope

We live in centrally heated homes, and when we do go outdoors in winter we wrap ourselves up in layer after layer of clothes, scarves, gloves, hats and other items designed to keep us warm against the cold. Birds don’t have any of that – so how do they cope?

The good news is that even the smallest birds have evolved over many thousands, even millions of years, to develop survival strategies. These include:

    (i)       Finding food:

Even though they may be very territorial during the breeding season, when male birds jealously guard their space against any rivals and incomers, in winter they behave very differently. They form flocks – sometimes with members of the same species, but often in mixed groupings with other, similar-sized birds.
    So in winter we see flocks of thrushes, finches, starlings, sparrows and buntings, often with two, three or more species involved; while the smallest birds such as tits or chickadees, nuthatches, creepers, goldcrests or kinglets, and even small woodpeckers will also form mixed flocks comprising half-a-dozen different species or more.
    This provides two major advantages: there are more birds searching to find food, which can then be shared out; and also more pairs of eyes taking a lookout for predators such as hawks, with only one bird needing to sound an alarm call for the whole flock to flee to safety.  
    Birds also regularly call to keep in close touch with the other members of their flock. This provides a real advantage for us birders: on a cold winter’s day, listen out for a series of high-pitched calls, and then look out for the birds making them – you may well have found yourself a mixed feeding flock!

Birds Finding Food in Winter


    (ii)       Keeping warm:

Birds are warm-blooded, like us, which means that their bodies can generate heat to maintain their internal temperature at the same level.
    Many small birds also keep warm by fluffing up their feathers, which acts rather like a duvet, trapping warm air underneath. Our ancestors realised the thermal qualities of birds’ feathers long ago, hence the use of eider feathers to make an ‘eiderdown’.
    At night they will also huddle up with other birds, which not only provides safety in numbers against predators, but also keeps them warmer than if they roosted on their own.
    Even so, a small bird can easily lose 10% of its body weight in just one night, making it even more essential that they feed early the following morning, to replenish their energy reserves.

Birds Keeping warm

    (iii)      Migrating:

Some birds take a very different approach: rather than staying put for the winter in the same area where they either bred or, in the case of first-year birds, hatched out and were raised, they travel to warmer climes for the winter.
    For some species, like the Barn Swallow, this involves epic journeys, all the way from Europe to South Africa, or from Canada to South America. But many migrants don’t go nearly as far: they may either travel a few hundred miles south, like the European Robins that arrive in the UK from Scandinavia each autumn. Others travel a far shorter distance: many garden and backyard birders in the southern states of the USA or southern Britain welcome new birds on their feeders each year, as birds which breed farther north come to their warmer, milder areas to spend the winter there.

    Where I live, in Somerset in south-west England, the departing swallows, martins, swifts and warblers are replaced in October and November by Redwings and Fieldfares – two species of ‘winter thrushes’ that arrive here from their breeding grounds in northern and eastern Europe.

Birds Migrating

3.  How we can help

The good news is that we can do a lot to help our backyard and garden birds survive during the winter – while at the same time enjoying amazing close-up views. And with your Birdfy feeder camera you can also take stills and video footage of your avian visitors, and post them on our Facebook groups.

We can help in several ways:

    (i)       Choose the best food:

When feeding the birds, it’s all about maximising the energy they get while minimising the time it takes for them to feed. Peanuts, for example, are not high in energy, while sunflower seeds are. And if you do provide seeds, make sure you choose those without the husks – I use kibbled sunflower hearts, which have had the outer layers removed, and have then been chopped in half, the perfect size for small birds to eat.

    (ii)      Make sure you keep your feeders topped up:

Birds tend to follow a regular circuit around several different locations, coming back to the same places – such as your feeders – again and again. But if you have allowed your feeders to become empty, they will have had a wasted journey, and even a brief period unable to find food might make the difference between survival and death. So make sure you keep your feeders topped up – and if you are going away for a night or two, ask a friend or neighbour to do so.

    (iii)      Keep your feeders clean:

A dirty feeder, especially one with old, mouldy food stuck to the bottom, can cause diseases that then spread rapidly through your local bird population. So make sure you regularly clean out your feeders.

    (iv)     Provide water as well:

Bird baths are the ideal way of providing precious water, not just for drinking but for bathing too. Small birds – especially those that mainly feed on seeds – need to drink regularly to top up their liquid levels; while a quick bathe removes any parasites, cleans up their feathers and keeps them in tip-top condition; essential for the bird’s continued survival.

Sadly, some birds will not manage to survive the cold spell – on average, especially for birds facing their first winter season, roughly one in two will perish.

Helping Birds


But the more you can do to give them a helping hand by providing good quality, regular supplies of food and water, the more chance they have of making it through to next spring, and continuing to delight us with their presence!

If you want to know more about birds, weather and climate change, do read my book Birds and Weather, published by Hamlyn in 1995, and now out-of-print, but available second-hand on these websites: USA and CanadaUK and Europe.

November 13, 2023 — Stephen Moss

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