Chiffchaff and willow warbler illustration

Similar summer visitors

Our spring dawn chorus gets a tuneful boost each year from migrant warblers, but while their songs are unique, some of them look frustratingly similar.

Willow warblers and chiffchaffs are two summer visitors that look so alike even experienced birders get them confused. They’re very active birds, so it’s often hard to get a clear view of them, and even when you do, many of their differences are quite subtle.

Both species moult in late summer too, which changes how they look, and their juveniles have slightly different plumage as well. There’s even a sub-species of chiffchaff to consider, and two other similar species of warbler that might flummox you.

This is a tough one, so don’t worry if you find yourself struggling. But if you’re up for the challenge, we have a few tips to help you.

Chiffchaff

Early herald of spring

Identification

  • Small birds, about the size of a blue tit
  • Slightly dumpy
  • Greenish brown with paler underparts
  • Thin, dark brown or black legs
  • Flicks its tale like a slow-moving wagtail

Call

Chiffchaffs say their name: ‘chiffchaff chiffchaff chiffchaff’. The song is a repeated sequence of two notes, usually descending, but sometimes reversed. They tend to arrive before willow warblers and can be very vocal when they first get here, which is often around mid-late March. They sing right throughout the spring, but then often go a bit quiet in the height of summer. You might also hear one calling in the late summer or early autumn as they migrate back down the country towards their wintering grounds in Continental Europe.

Flight

They’re quite restless little birds that seem to be always on the move, so it can be hard to get a clear view of one. Their flight is a bit jerky, and if you do see one perched, they rarely sit still, often wagging their tails and flicking their wings. You’ll sometimes see them fly out to catch insects from the air.

Nesting

Chiffchaffs like to nest in deciduous or mixed woodlands, choosing areas with dense undercover. They build their nests very close to the ground, often in brambles, but will also use tall grasses and nettles. They can have two broods in the year, and the males play little part in chick rearing.

Where to look

Less common than willow warblers, chiffchaffs can still be seen almost right across the UK except in the far north and west. They’re migrant birds, but some are now choosing to winter in the south of England. They’re most visible in late March or early April, and you might see or hear them in leafless trees, particularly willow trees, searching for insects. During the summer, they’re more of a woodland bird and become harder to see. When they migrate south in the autumn, they sometimes visit gardens to refuel and wait for good travelling conditions, and during this time you can often hear them singing again. This may be young birds ‘practising’ for the following spring.

Chiffchaff song

Patrik Aberg, Xeno-canto

Willow warbler

Facing declines

Identification

  • Small birds, about the size of a blue tit
  • Slightly thinner and longer than chiffchaffs
  • Greenish brown with paler, often yellowy, underparts
  • Lighter brown legs
  • Clearer yellow stripe over the eye

Call

For many people, the song of the willow warbler is the sound of summer. It’s a fairly simple song, just a long, high descending sequence of notes that pops up a little at the end. In fact, it’s not a million miles away from the song of the chaffinch, but it’s sweeter and softer, and the ending is less punchy (it’s brilliantly described in Bird Guides as a ‘chaffinch-on-helium’!) You’ll hear the song from early April onwards and right through into the summer, but unlike the chiffchaff, you won’t hear it singing in autumn.

Flight

Willow warblers spend their winters in Africa, so they have further to fly on migration than chiffchaffs. This makes them stronger fliers and gives them slightly longer wings. When you see them perched, they’re not quite as jumpy as chiffchaffs, and they flick their tails much less.

Nesting

While chiffchaffs prefer woods, willow warblers are more often found in scrub or on woodland edges, and will even nest on brownfield sites if there is suitable habitat for them. The nests are dome-shape and often on the ground, but well hidden in undergrowth. Some males may try to support two females and two nests at the same time.

Where to look

Although they’re more common than chiffchaffs, willow warblers have actually suffered declines in recent decades. They’re widespread throughout the UK, and can be seen and heard from their arrival in early April right through to their migrations in September. Unlike the chiffchaff, willow warblers won’t spend the winter in the UK, so that can help with identification through the colder months. Like chiffchaffs, they’re often most visible when they first arrive when you can see them hunting for insects in leafless trees.

Willow warbler song

Patrik Åberg, Xeno-canto

Warbler overload!

Chiffchaffs and willow warblers are both quite common, but there are two other similar species of warbler to look out for which are much rarer.

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