European Pied Flycatcher

For a species that does not use a flight call by day, it is surprising that on September nights in south-western Europe the most frequently recorded nocturnal flight call is the buzzing, strongly modulated zzz of European Pied Flycatcher Ficedula hypoleuca. Further north and east, patient observers will detect much smaller numbers, and in spring the geographical pattern is completely different.

The reason for this is the exceptional migration strategy of Pied Flycatcher (Lundberg & Alatalo 1992). In autumn, individuals start their migration in a south-westerly direction, which concentrates most of central and eastern Europe’s birds in western Iberia (with Portugal being a major stop-over site). At this season, they are far more likely to be heard at night in western or south-western countries (eg France, Spain and Portugal) than in central Europe. On the night of 19-20 September 2019 for example, an estimated 1,302 individuals called while flying over Sagres, the southwest corner of Portugal (total: 1,959 calls).

Returning north in spring, Pied Flycatcher demonstrates what is meant by ‘loop-migration’. A more direct route takes the bulk of the population much further east, over the Balkans. Presumably only much smaller north-western European populations pass further west at this time. As a result, we have not yet recorded NFCs in spring, neither in Portugal nor in Germany.

Although most birdwatchers are unaware of it, Johann Friedrich Naumann described the main NFC of Pied Flycatcher two centuries ago: “Its nocturnal call, which one can hear on its migration, as well as from captive birds, is a loud slightly rasping Shreet!“ (Naumann 1822). We prefer to spell it simply zzz, in order to emphasise its buzzing or harsh quality. When there are high concentrations of migrants, this call can also be heard frequently in daytime, but not in flight. Instead it seems to serve as an aggressive signal, marking the limits of feeding territories.

The best known call of Pied Flycatcher during the day is a sharp, rising wit, and this can also be heard at night, albeit much less frequently than zzz. It is gratifying when Pied Flycatchers combine the two call-types into a third: zzz-wit. Since other flycatchers such as Spotted Flycatcher Muscicapa striata or Collared Flycatcher F albicollis lack anything resembling wit, the combined call-type is very helpful for identification. This is, however, the least often heard of the three call-types.

zzz calls

• highly variable in length, frequency range, shape and modulations
• duration 106 – 207 ms (90% range; median 142 ms; n = 101)
• two bands, roughly parallel, typically more than 1 kHz apart, closer at end, and sometimes at start (see examples b, e & j); upper band weaker (f & g) and occasionally absent (i)
• frequency 1.7 – 9.3 kHz (mean min 4.4 kHz; mean max 7.8 kHz; n = 101)
• overall shape usually a descending arc; near-symmetrical arc-shape also common (d, g); minority show an overall rise in pitch, eg. an arc reaching its highest point during second half (e)
• most calls descend sharply at the end in one or both bands, showing a ‘hindleg’ in sonagrams (a, b, c, e f, I & j); calls that are atypically straight, not curved, usually still show this (c)
• fine modulations almost always give a buzzing or harsh quality, particularly at the start of the call; median maximum rate of modulation 100 Hz (90% range, 52 – 126 Hz; n = 101)
• modulations become shallower in the course of the call, often disappearing altogether by the end (a, b, d & k)
• deeper modulations produce very coarse timbre (i) especially when combined with secondary modulation: a slower and deeper oscillation superimposed on the usual faster rate (k & l)

Effects of recording quality

• Closer calls have more than two bands and a lower final frequency.
• Distant calls appear shorter as fine details at start and end disappear (darker blue features on sonagrams); upper band becomes weak or disappears; shallow modulations become blurred and difficult to discern

wit calls

• duration 61 – 111 ms (90% range; median 77 ms; n = 46)
• usually two frequency bands, lower one much stronger (see examples m & r)
• rapidly rising pitch is dominant impression; stronger, lower band starts as low as 2 kHz and rises rapidly to a peak at 4.6 – 6 kHz (90% range; median 5.3 kHz; n = 46); weaker, higher band starts higher and peaks at 5.2 – 7.1 kHz (90% range; median 6.0 kHz; n = 43)
• overall shape arched in both bands, with peak right of centre and descending part faster and more difficult to hear
• generally unmodulated; in a sample of 46, six had fine but shallow modulations (o, p), not enough to give buzzing timbre
• upper band often peaks slightly earlier than lower band (p, q & s)

zzz-wit calls

• duration 345 – 508 ms (90% range; median 421 ms; n = 38)
• always zzz first then wit
• zzz higher-pitched and longer than wit
• full range of variation of zzz and wit calls used in this combination
• interval of 261 – 431 ms between start of zzz and start of wit (90% range; median 358 ms; n = 38): time configuration pretty consistent
• regarded as a single call in counts for, eg, trektellen

zzz calls

• Spotted Flycatcher Muscicapa striata NFCs are shorter, less descending, occupy narrower frequency range and have straighter bands. Any fine modulations will be upward-pointing spikes, lacking in the beginning. No downward-pointing ‘hindleg’ at the end, but often a spike.
• European Robin Erithacus rubecula NFCs are a little over half the length, considerably higher-pitched and lack fine modulations.
• Tree Pipit Anthus trivialis NFCs may appear similar at distances where the upper band of Pied would disappear. Doubled or tripled calls easily exclude Pied Flycatcher. Single calls more arched than Pied, with modulations distributed more evenly throughout the call.
• European Blackbird Turdus merula NFCs have two or more bands with modulations, but are higher-pitched and with much slower modulations; often doubled or tripled.

wit calls

• Ortolan Bunting Emberiza hortulana has a plik call that is also typical of early to mid autumn nights. It differs in having an initial spike, giving the whole call a shape similar to a rather angular small case letter ‘n’.

• anywhere: over towns, forests, mountains, offshore
• strictly nocturnal: no known diurnal flight calls
• can be expected at any hour: a bias of activity towards second half of night

Separation from other Ficedula flycatchers is still in its infancy. We have ideas about Collared Flycatcher and Red-breasted Flycatcher F parva NFCs but these are mostly based on zzz-type calls they give during the day. We know NFCs of Mugimaki Flycatcher F mugimaki and Grey-streaked Flycatcher Muscicapa griseisticta from the Far East, where many more flycatchers species can be heard at night, but we still have nothing to say about NFCs of Atlas Flycatcher F speculigera or Semi-collared Flycatcher F semitorquata. The iberiae subspecies of European Pied Flycatcher has a song quite different from the nominate. However, the evidence from daytime that its zzz and wit calls are probably too similar to the nominate to distinguish. The examples above may include some iberiae, although this subspecies is swamped in autumn by vast numbers of Pied coming to Iberia from as far east as Siberia.

Lundberg, A & R V Alatalo 1992. The Pied Flycatcher. London.

Naumann, J F 1822. Naturgeschichte der Vögel Deutschlands. Volume 2. Leipzig.