A Tricky Subalpine Warbler

A Subalpine Trap : an interesting “cantillans” makes things hard !

by Andrea Corso, Michele Viganò, Ottavio Janni & THE MISC

The Subalpine Warbler Sylvia cantillans (sensu latu) complex is one of the most interesting Sylvia taxa in the Western Palearctic; its variety of taxa, complicated taxonomy and identification – not least its obscure nomenclature, which warrants an in-depth review (see Brambilla et al. 2006, 2008, 2009; Baccetti, et al. 2007; Svensson, in prep.; Corso & Janni, pers.obs.) – its distribution and the poorly-known female/juvenile plumages of the various taxa makes it truly intriguing for any serious birder.

When faced with a bird that does not neatly fall into a box, the identification of Subalpine Warblers becomes even harder, and this is the story of one of those moments that forces you to question your knowledge, which all of a sudden does not seem to be nearly as thorough as you thought! We are all quite familiar with Subalpine Warblers, since Italy is undoubtedly the best country in Europe to study all the various taxa and observe them in large numbers both during migration and on their breeding grounds. But when coincidence and variability throw a spanner in the works, then we all need to go further.

Shirihai et al. (2001), in their seminal work on Sylvia Warblers, report that “Specific separation of female-like (including 1st winter) plumages of Ménétries’s from Subalpine poses one of the greatest field identification challenges among Sylvia.”

We realised just how true this is in November 2012 in our birding paradise, the island of Linosa. It was the evening of November 5th, and we were quite happy with our haul over the previous few days: an obliging Daurian Shrike just 50 metres away from an Olive-backed Pipit (3rd of the autumn in Sicily), a Rustic Bunting in a tiny vineyard near our house, several Yellow-browed Warblers alongside with some good snorkelling – try doing that on Shetland in November! -and more…

AC was carefully studying an Acro showing characters of Marsh Warbler, a rare migrant in Sicily, when on the same olive tree a Sylvia sp. appeared on the highest branches. It was very pale, uniformly sandy coloured with…a strikingly contrasting BLACK TAIL !!!! Alarm bellsstarted to ring in the rarity-hunter’s addled brain…

The most obvious ID was Subalpine, but in a place like Linosa everything is possible, and Ménétries’s Warbler is already on Italy’s impressive list (536 species despite having very few active birders – the list could be much longer!).

After a quick glimpse the bird flew off, showing a featureless body with an obvious black tail: almost like a juvenile Red-breasted Flycatcher (or a Blackstart).

Do you know that feeling when the heart is pounding, breathing is as difficult as it would be under water, walking is as hard as having wooden legs or walking on the moon (to quote The Police J )… OK, that was the feeling AC had. He alerted Igor Maiorano and the others to have a careful look as this could be “something” really epic.

For the next half an hour, we studied the bird: in the field the tertials did not look particularly contrasting and the pale fringes disappeared in the intense Sicilian sun, so they that they looked plain, even under prolonged observation! The alula was almost solidly black with broad and obvious pale fringing, contrasting as a black patch against the uniform wing, the primary projection appeared very short, the wing itself being rather round-looking with a round-tipped impression, the wing-tip falling short the longest undertail coverts (in albistriata it is level with them or longer), the bill appeared deep-based and rather down curved but quite short, the base of the lower mandible was clearly pinkish tinged, the lores were very pale, and the eye-ring very bright and conspicuous.

The sunset arrived too soon, and OJ, MV and several others did not arrive in time to see the bird, as they were birding on the opposite side of the island (the area that we call “the dark side” since there is no mobile coverage and is always risky to go birding there ).

But the next day the bird was still in the same trees, and we all could study the bird in the field: the contrasting black tail was impressive but as noticed by AC the previous day, it was re-growing !

The bird uttered a call unlike Ménétries’s Warbler calls we known, but it also sounded different, at least slightly, from typical Italian Subalpines, obviously from the diagnostic double note of albistriata, and of course totally unlike Moltoni’s wren-like trill. A sound recording was secured by MV to obtain sonograms.

The tail pattern was also interesting: T6 (or R6 if you like) was a better fit for Subalpine sensu latu, being almost wholly pale but for a long, narrow tongue” running along the outer edge of the inner web; but the pattern of T5 (R5) was however better for Ménétries’s, being fully slate grey with a blackish tinge and a well-marked white apical notch.

We were still a little puzzled, chiefly due to the tail pattern and colour and contrast and the short-looking primary projection.

We decided to ask the opinion of our friend Yoav Perlman on the plumage – as he has handled and observed in the field far more Ménétries’s Warblers than we have – and to consult our sound-guru Magnus Robb, from the Sound Approach to Birding team, for an opinion on the call.

However, before their opinions arrived later on, the night brings good counsel and often nice dreams (in OJ’s case,he dreamt of the Daurian Shrike two nights before actually finding it!) … and the day after we decided that the mystery Sylvia was most likely a “Subalpine Warbler” – perhaps from the North African population (inornata) – which had lost is tail and was re-growing it with an adult-type pattern and COLOUR. Tertial’s pattern and call sonograms indicate this identification.

All in all, as Martin says – always learning !

TAIL PATTERN: tail pattern is reported to be a very helpful clue in several references, including Alstrom et al. (1991) and Shirihai, et al. (2001), with the T5 (R5) on adult-type tail constantly illustrated as different in the two species, Subalpines showing more white, as a wedge intruding into the feather along the shaft, and the pale patch itself less well-defined, while in Ménétries’s the apical “notch” or “blotch” of T5 is smaller, rounder, and very well-defined against a more intensely blackish ground colour. The odd Sylvia from Linosa has re-grown its tail into an adult-type (the feathers being dark and round-tipped instead of sand-colored, pointed, and narrow as in juveniles): T5 is a better fit for Ménétries’s, but we found an obvious amount of variability in tail pattern among the “Subalpines” complex, with some “Subalpines” showing much less white on T5 and T4 (or nothing on T4) and with the pale areas being smaller and more demarked (Shirihai, et al. (2001), but mostly see Svensson, in prep. and photos). Also, in juvenile “Subalpines” the tail is surely much paler than in our bird and in Ménétries’s, more sandy-buffish brown, while in adult “Subalpines” is darker grey, sooty grey or dark grey blackish tinged (mostly on the distal part). So the re-growing tail on our mystery bird showing adult-like colour is obviously contrasting with the pale juvenile body!

TERTIAL PATTERN: this is one of the clinching characters and therefore one of the most important. It should be underlined that in the field it was very hard to really be sure about the pattern, as in some angles and with intense light the well-defined pale fringes fade away and almost disappear, making the entire tertials look rather pale and uniform. Also, caution should be paid on any moulted or worn tertials, where the fringing can narrower or be less well-defined than usual on Subalpines. In our bird, the photos show the fringes to be rather bright and well-defined, with a rather demarked dark centre, making the bird a“Subalpine”. Fringes are usually better defined in S Italian taxon and on albistriata, less so in Moltoni’s Warbler (but what about Western taxa such Spanish and N African ones?), but this is however quite variable in all taxa. In Ménétries’s Warbler, the dark centres on all tertials are not well demarked, being less dark and with less defined borders than in Subalpine, being in fact diffuse and not much contrasting with the suffuse fringings, all in all they appear more uniform and less obviously patterned.

BILL: the bill appeared rather heavy and broadly based; this is better for Ménétries’s (Shirihai, et al.2001) as this species usually has a broader-based, often longer and more decurved bill than Subalpine (even more than a Sardinian Warbler in fact ! – see figure). However, without direct comparison this is pretty hard to judge in the field, and this feature is better assessed in the hand. Also, sure it is variable among sex/age and taxa groups of “Subalpine”.

CALLS: the calls are distinctive, but we read in both Svensson et al (2010) and in Alstrom et al. (1991) that they variable, with the latter authors reporting that Ménétries’s also has a “dack” call which might resemble some Subalpines calls. Our bird from Linosa had a call that matched “nominate” Subalpine, but which to our ears sounded a bit different from those we are used to in Italy. Could it be an inornata from Tunisia, whose calls we don’t know ? Also, it would be nice to find any sound recording of the “dack” call of Ménétries’s, the one reported in some quoted references…

WING PATTERN : Shirihai, et al. (2001) mention differences in the alula pattern, with Ménétries’s showing in general a blacker centred alula contrasting more with the rest of the wing, and showing better-defined and broader edging; however, our bird on Linosa had such a pattern and we found this to be highly variable and often overlapping. The differences on wing-formula (like the length of P1 and the P1:PC ratio) are only helpful in the hand or in very close up good photos.

PRIMARY PROJECTION (PP): reported to be shorter in Ménétries’s, with primaries tips more bunched together; whereas PP is longer, narrower, and more pointed in Subalps, with 7 well spaced primaries. In our bird the PP was pretty short and the wing looked short and rounded; however, we found that some birds (some taxa) of the Subalpine complex, like for ex. Moltoni’s Warbler could show a shorter PP, on account possibly of their different migration pattern (the shorter distance migrants having a shorter PP). Could the Linosa bird be an inornata (as Moltoni’s was excluded straight away by the call) ? And does inornata, being from N Africa, really have a shorter PP? This should be further investigated …

BEHAVIOUR: behaviour is one of the most helpful identification clues for many birds, and is crucial is separating two very similar looking Sylvia like Tristram’s and Spectacled Warblers, as well as the two species we are discussing here – in fact Ménétries’s habit of constantly twisting and fanning its tail is not shared by Subalps, which usually hold their tail still or move it slightly up and down. Indeed, our bird always held its tail still.

We finally concluded, supported by Yoav Pearlman and Magnus Robb’s opinions on plumage and call features, that the bird was more likely a “Subalpine Warbler”, possibly a North African one (inornata).

PHOTOS OF MYSTERY SYLVIA WARBLER LINOSA NOVEMBER 2012 – MISC

1

  1. Sylvia Warbler, identified as “Subalpine Warbler” (sensulatu) from Linosa Island, Pelagie Archipelago (Agrigento, Sicily) from November 5th 2012. Note the very pale sandy coloured plumage with a richer tawny tinge on mantle, the bright contrasting throat with creamy-apricot or buffish tinged flanks and breast side, the very pale lores, the obvious eye-ring, the be-coloured bill, the yellowish-flesh legs and the short looking tail. (Igor Maiorano – MISC)2
  2. Same bird in flight; note the strikingly contrasting slaty blackish tail, almost solidly black on the distal portion, which combined to the white lateral side is giving to the bird an almost Red-breasted Flycatcher impression. This is typical of Ménétries’s Warbler rather than any juvenile “Subalpines”, but the tail was re-growing with an adult-type pattern and color, therefore darker than in juv. and obviously contrasting with the pale body. (Igor Maiorano – MISC)3
  3. Same bird. Note the very dark black alula with obvious pale fringing, reported in field guides to be more typically found in Ménétries’s Warbler rather than in “Subalpines”. However, we find this character highly variable and therefore of limited – if any- use. (MicheleViganò – MISC) 4
  4. Same bird in a different light and angle – note the dark centred tertials with well visible and contrasting being well defined pale fringing. This seems to be the clinching character for it being an odd Subalpine Warbler rather than a Ménétries’s Warbler. However, note that in the field the fringing where never so obvious and the contrast never appear such dramatic, appearing the tertials rather uniform ! It is hard indeed …!!(Michele Viganò – MISC) 5
  5. Same bird – note the similarities with the juv. Ménétries’s shown in fig. 15, especially the very pale lores giving a “wide open” face looking, the complete and wide pale eye-ring, the short and thick based bill (with a pale base, appearing horn-grey but that in the field shown a pinkish-flesh hue or tinge). (Michele Viganò – MISC) 6
  6. Same bird – note the tail pattern with T6 almost entirely white but a long narrow blackish sandy-grey “tongue” running along the outer margin of the inner web, like in most “Subalpines”, while T5 showing only a small white apical notch as in Mènètries’s. Note however that tail pattern is variable in the cantillans-complex and “Western Subalpines” including Moltoni’s W could show similar pattern as in our Linosa bird. (Michele Viganò – MISC) 7
  7. Same bird (Michele Viganò – MISC) 8
  8. Same bird- sonograms of the call. Note the clear and sharp tack or dgiack calls, readily different from Moltoni’s and double notes of albistriata, but what about inornata and Western Subalpines? What about the “dack” call type reported for Ménétries’s by Alstrom, et al. (1991) and some other references? Would be interesting to compare sonograms of all these taxa. (Michele Viganò – MISC) 9
  9. Typical tail pattern of Eastern taxa of “Subalpines”, where the T5 pattern is different from the Linosa bird and from typical adult Ménétries’s with an obvious “tooth” from the tip into the feather along the shaft. (A.Corso, Museo Civico di Zoologia di Roma, MCZR) 10
  10. Typical T6 and T5 pattern of Eastern Subalps, with a quite long “tooth” or “tongue” on T5. (A.Corso, MuseoCivico di Zoologia di Roma, MCZR) 11i
  11. Typical tail pattern of a Moltoni’s Warbler from Sardinia, showing T5 pattern like in Linosa bird and on adult Ménétries’s Warbler, showing only a small and defined “notch” on the tip of T5 (the call however is always different from those taxa). (A.Corso, Museo Civico di Zoologia di Roma, MCZR) 12
  12. Same tail from below (A.Corso, Museo Civico di Zoologia di Roma, MCZR) 13i
  1. Bill seen from below in Sardinian (left) and Ménétries’s Warbler (right) to show the stronger, shorter and deeper based bill in the latter, similarly to the differences noticed when compared to Central and Western Subalpines taxa. (A. Corso, courtesy of Tring, NHM). 14i
  2. A beautiful 2nd cy male Ménétries’s Warbler from Israel. Note the diffuse dark centre on the new (moulted adult) middle tertial which also shown vague and diffuse fringing, differently to Subalpines and to Sardinian (Yoav Perlman). 15i
  3. A juv. Ménétries’s Warbler from Israel. Note that the bird is almost identical to the odd Sylvia from Linosa, and would be indeed identical if the tertials would not be typically more uniform, homogenously pale with only slightly darker suffuse center which contrast only barely with the unmarked, badly defined and not marked suffuse fringing. This would seems to be the clinching character to identify any juv. Subalpine from Ménétries’s. (Y.Perlman) 16
  4. Tail of the same juv. of Fig. 15 – note how much black is already in juvenile plumage, note the pattern of T6 with lot of black along the centre and along the shaft, and T5 fully black with a small white notch at the tip. Note as well the uniform tertials lacking any strong contrasting pattern. 17
  5. A typical adult female Ménétries’s Warbler from Eastern Turkey, Igdir (Michele Viganò- the MISC), June 2013. Note a very typical ad female with very uniform cold silk grey upperparts lacking almost altogether any rusty tinge, very dull underparts, broad diffuse greyish-brownish grey fringing to tertials, dull barely marked pale lores and the distinctive long-looking dark black tail. 18
  6. Same bird in different position. Note the short and blunt primary projection and the constantly moved tail in a cat-like fashion (as in Tristram’s Warbler and contrariwise in Subalpine and Spectacled). 19
  7. Same bird. Note the clear cut pattern of the T6 and the pattern of T5. 20
  8. A fresh juvenile Italian Subalpine Warbler. Note the bright rusty tinge to wings and head, the well demarked and defined pale lores and the pale tail. by Davide D’Amico21
  9. Same bird from different angle. Note as from some angle at least the central tail may appears rather blackish tinged , however, note the obvious and marked rusty tinge to crown (forming as a little “hat” against the pale lores and subtle supercilium). Underparts bright milky white by Davide D’Amico.
  10. Sound record of the call of the bird from Linosa <here>

Acknowledgements

We whish to thanks as always Dr. Carla Marangoni, curator of the ornithological section at MuseoCivico di Zoologia in Roma (MCZR), where a great collection of “Subalpine Warbler” (sensulatu) skins are preserved. On the same way a warm thanks goes to the Tring, NHM staff to which we are very much indebted for the most important help for any of our birds plumages studies : so a warm thanks goes to Katrina Kook, Robert-Pries Johanes, Mark Adams and the others working at Tring and that helped in various way.

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About Martin Garner

I am a Free Spirit
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5 Responses to A Tricky Subalpine Warbler

  1. Andrea Corso says:

    For a VERY DETAILED publications on all the various taxa of Subalpine-complex, please wait seminal paper by Lars Svensson in prep., as quoted, so it is forthcoming !! Be alerted and wait his paper and all the details and the complex will be solved !

  2. Davide D'Amico says:

    Thanks Andrea

  3. Hannu Jännes says:

    Bird in fig 17 looks like very fresh juvenile not ‘typical adult female’.

  4. Andrea Corso says:

    Hannu,
    thanks for pointing as we forgot to change the captions….
    obviously it is a typo..indeed it is a fresh juv. recently fledged and as ALL the other photos we included, the photos were reported to compare juveniles /2nd cy of Subalps and Menetriès’s ! iris colour, wing feathers and tail and so on all point towards this age, and it was with adult male and adult female. So indeed, they captions should be typical juv. ….
    thanks and ciao

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