Icterine WarblerHippolais icterina Texel, Noord-Holland, Netherlands, 6 June 2011 (René Pop).

Other than Eurasian Reed Warbler, if I am to find any of these species in Dorset singing in spring the song is likely to be plastic, since spring overshoots tend to be first-year birds whose songs will only crystallize when they know they have reached their destination and stake out their territory. It is thought that females recognize plastic songs as experimental and avoid interacting with the singers.

Plastic songs of Marsh Warblers still migrating towards their breeding grounds are less clearly structured and it becomes a bit more difficult to discern any regular cycle between faster and slower material in the song. They may include longer sections of frenetic singing than crystallised song, and fewer slow sections with simple repetitions of a single sound or species. Nevertheless, the diagnostic rapid alternations, za wee-style, are all there, and so is the trip report (in progress) for anyone able to follow it!

Marsh Warbler Acrocephalus palustris Göksu Delta, Mersin, Turkey, 15 May 2001 (Magnus Robb). Plastic song of a spring migrant. Background: Wood Sandpiper Tringa glareola, Graceful Prinia Prinia gracilis and Eurasian Reed Warbler A scirpaceus. 01.019.MR.11650.00

Eurasian Reed Warbler's plastic song is a wonderful thing. Plastic songs by nature lack the steady structure of adult song, they have irregular rhythms, surges and calls interspersed. Not this Eurasian Reed. Its need for tidiness makes it create a steady plastic song, one that causes no inconvenience with everything in the right drawer, just some slight wobbliness and muttering as it goes through its rather steady paces.

Eurasian Reed Warbler Acrocephalus scirpaceus Port de Pollença, Mallorca, Spain, 12:26, 9 May 2016 (Magnus Robb). Song of a spring migrant in an olive tree. Note that Ambiguous Reed Warbler A baeticatus ambiguus arrives early in Iberia and a migrant would be unlikely at this date. However, plastic song of Ambiguous probably sounds extremely similar. Background: Common Nightingale Luscinia megarhynchos and Cetti's Warbler Cettia cetti. 160509.MR.122606.01

By contrast, Blyth’s Reed Warbler's plastic song is far more musical and varied, so much so that migrating and breeding males can sound like two different species. This is a bird in a hurry. If you identify Acrocephalus songs only by speed, then Blyth's plastic song will throw you. They sound as if they are insecure about the size of their repertoire, checking how much they have and hardly pausing to repeat anything in cycles. Remember, the thing that makes the song of Blyth’s on the breeding grounds sound slow and steady is the long cycles and consequent slow repetition rate. With plastic song of migrants, instead of speed, the clues are in the type of sounds the song is made up of, with plenty of short tak-like notes and a variety of more tonal sounds. It may sound as varied as a Marsh Warbler song but lacks the za wee-type motifs and shows far less contrast in terms of velocity within the song. No sudden frenetic outbursts, just a steady variety-check.

Blyth's Reed Warbler Acrocephalus dumetorum Chokpak pass, Dzhambul, Kazakhstan, 2 May 2000 (Magnus Robb). Plastic song of a spring migrant. Imitations in this song include White-winged Tern Chlidonias leucoptera and Graceful Prinia Prinia gracilis. 00.020.MR.00720.00

The challenge with Icterine Warbler plastic song is a similar one. There are few of the characteristic 'broken record chunks' and you have to focus on the timbre and the kinds of species imitated. Their timbre in plastic song is unmistakeably the same 'squeaky toy' sound that they use on the breeding grounds, except during those moments when they descend into a kind of whisper song. With this migrant from Greece you can hear some typical imitations, including a Barn Swallow, Eurasian Golden Oriole Oriolus oriolus, Eurasian Hobby, Fieldfare T pilaris and Common Rosefinch Erythrina erythrina (0:37). It's funny to think that a month or two earlier it was probably imitating rosefinches in South Africa while the very rosefinches it learned the sound from were wintering in India. Of more practical use, any unidentified Hippolais in the UK that is imitating Fieldfare and Common Rosefinch will hardly be an overshooting Melodious Warbler from southwestern Europe, but must be from northeastern Europe and is therefore Icterine.

Icterine Warbler Hippolais icterina Lake Mikri Prespa, West Macedonia, Greece, 7 May 2002 (Magnus Robb). Plastic song of a spring migrant, with imitations including Fieldfare Turdus pilaris and Common Rosefinch Erythrina erythrina. Background: Eurasian Golden Oriole Oriolus oriolus and Common Nightingale Luscinia megarhynchos. 02.023.MR.14516.01


As for Melodious Warbler, we have recordings of its plastic song from Africa. It is a fairly common wintering species in Ghana, and Magnus recorded a couple there in November. Their plastic song is as fast and furious as their song on the breeding grounds but has less clear-cut 'broken record chunks', incorporates more rattling contact calls, and occasionally descends into whispered subsong.

Melodious Warbler Hippolais polyglotta Mole National Park, Savannah region, Ghana, 10:01, 16 November 2019 (Magnus Robb). Plastic song of a wintering individual. Background: Vinaceous Dove Streptopelia vinacea. 191116.MR.100102.01

It would be fascinating to know more about the songs of our warblers during the non-breeding season, when they are far away. Are they defending feeding territories or just practicing? Do adults sing as much as first-winter birds? And do they often betray their European origins with mimicry of species from Europe? Magnus heard a Melodious Warbler imitating a Barn Swallow and European Bee-eater M apiaster, for example, but it could have heard those in either continent. More recordings would surely give a clear example or two. Another good excuse to return to Africa, says he.

In your dreams, Magnus!

 

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