The Common Chiffchaff (Phylloscopus collybita) is the brownish cousin of the Willow Warbler — almost identical visually but easy to separate by voice: a monotonous, mechanical repetition of "chiff-chaff" that gives the species its English name. It is small, 10–12 cm long with a wingspan of 15–21 cm and a weight of just 6–9 g, olive-brown-green above and dingy whitish-yellow below, and its dark legs are the key visual mark separating it from the pale-legged Willow Warbler.
The song is a monotonous, mechanical, alternating "tjif-tjaf-tjif-tjaf", repeated at an irregular pace almost without end — the notes stay at nearly the same pitch though their order can shift, as in "tjaf-tjif", which keeps the melody distinctive rather than tiresome. The species sings for many hours a day, starting soon after arrival in late March and continuing into July, with a peak in early morning but activity through the day in clear weather, typically from a semi-hidden perch in mid-height foliage. The contact call is a distinct, sharp, upward-inflected "huit" — almost like a spoken question mark — while the alarm is a hard, repeated "hwid-hwid"; the song remains the surest way to tell it from the Willow Warbler, whose song is a soft, wistfully descending scale utterly unlike the mechanical chiff-chaff. It breeds across the whole region up to the birch forest zone, in mixed and coniferous woodland with undergrowth, often in damper spots than the Willow Warbler prefers, with a Swedish population of around 800,000 pairs. As a short-distance migrant it winters around the Mediterranean and North Africa, with some remaining in Western Europe, and arrives back in late March to early April, earlier than the Willow Warbler. The nest is a domed, roofed structure with a side entrance, built low in dense undergrowth or on the ground, well hidden in grass and brush; the female lays 5–6 eggs, incubated for 13–15 days, typically a single brood per season. The diet consists of small insects, larvae and spiders, and the species is classified as Least Concern (LC).
Read about this species in Swedish →