When the days grow shorter and temperatures fall, the birdlife of the UK undergoes a quiet transformation. Many of the species associated with spring and summer – warblers, swallows, swifts – have long since departed for warmer climes, leaving behind a different cast of characters. The winter months bring their own richness: hardy residents such as robins, blackbirds, and wrens adapt their behaviour to cope with scarcer food supplies and colder conditions, while flocks of migrants arrive from northern Europe and beyond.
Famous summer bird migrants, such as the cuckoo, often capture our focus. However, wintering migrant bird species deserve special attention. The most visible winter visitors to the UK are wildfowl – ducks, geese and swans – which migrate in their thousands from distant breeding grounds in Canada, Greenland, Svalbard and Siberia, as well as from nearer strongholds in Iceland and Scandinavia.
Most bird surveys in the UK are carried out during the breeding season, typically from April to July. This focus on spring and summer is understandable, as birds are more vocal, easier to detect, and breeding success is a key conservation measure. However, concentrating exclusively on this period overlooks an important part of the annual cycle.
Why is surveying our winter birdlife important?
Based on our national survey datasets, we have found a significant portion of species is missed from surveys when only surveying during the spring/summer period. We analysed data from 99 locations where standardised bioacoustic surveys had taken place in the UK bird breeding season, and winter. While many species were identified during both seasons, almost one in four species (23%) were only detected only during the winter period. This highlights the critical value of winter bioacoustic monitoring: without it, a significant portion of the community would be overlooked. Ensuring that surveys include both summer and winter seasons provides a more complete and representative picture of biodiversity and strengthens the evidence base for conservation planning.
Winter is also a critical period for the survival of birds. Food is scarcer, temperatures are lower, and daylight hours are short, meaning that energy budgets are under intense pressure. Migratory species arriving from northern Europe, Iceland, or Siberia rely on the UK’s habitats to provide safe roosts and adequate feeding opportunities. Resident species must also adapt their behaviour to cope with these constraints. Monitoring bird populations in winter therefore provides not only a more complete measure of biodiversity, but also a direct indication of how well our landscapes are supporting birds during their most challenging season. In this sense, winter monitoring may be the most revealing measure of all: it tests whether habitats are functioning effectively at the time when birds depend on them most.
What can I look out for?
In total, approximately 40 species of birds regularly migrate to the UK for the winter months, making up millions of birds. Additionally, many more species migrate within the UK, or can show different behaviours which make them more likely to be detected during a bioacoustic survey. A few common groups to look out for include:
- Migratory thrushes such as redwing and fieldfare are classic winter visitors to the UK, breeding in northern and eastern Europe before moving south each autumn. In winter, they descend in their thousands to feed on berries in hedgerows and orchards, their calls often a distinctive feature of the colder months. Their presence is entirely seasonal, making them invisible to summer-only surveys. They often gather in large flocks for warmth and safety.
- Owls such as tawny and barn owl are resident in the UK year-round, but their calls are most prominent in the autumn and winter months. Tawny owls in particular become highly vocal during this period, using their characteristic hoots and calls to defend territories and strengthen pair bonds ahead of the breeding season. Barn owls, too, may be more frequently detected in winter as longer nights extend their hunting activity and vocalisations.
- Meadow pipits are good examples of seasonal migration within the country. The meadow pipit is one of the UK’s most widespread breeding birds, yet its detectability varies strongly with the seasons. While present in summer, birds are dispersed across upland and farmland habitats, where their calling can be relatively inconspicuous. In winter, however, many meadow pipits move into lower-lying farmland and coastal areas, often forming larger flocks.
Prominent changes can be seen in our birdlife at almost every habitat during the winter months. Even common garden species adjust their routines, foraging more actively during the short daylight hours and can be found heavily on garden feeders to sustain them.
So what can you listen out for in the coming months? While many species reduce their vocal activity outside the breeding season, robins and wrens continue to sing regularly, often being most noticeable on cold mornings and evenings. The arrival of migratory thrushes also adds distinct sounds, with the high, thin calls of redwings heard and the chattering of fieldfares carrying across hedgerows and farmland. If you’re lucky, you may witness waxwings in towns and gardens, recognised by their soft trilling calls. At dusk, larger gatherings dominate the soundscape, with starlings producing varied whistles and clicks in pre-roost flocks, and rooks and jackdaws calling in large numbers as they assemble at communal roost sites.
Interested in learning more?
Learn more about the sounds of our seasons here. Want to learn more about winter bird monitoring? Get in touch here.