The Italian Job?

ilyabirding
May 4
11 min read

Updated: May 5

A puzzling Subalpine Warbler (or two)?

On 2nd May 2025, Dave Collins turned up a cracking Subalpine Warbler just north of Kynance Cove. Its identity — Eastern, Western, or Moltoni’s — sparked plenty of debate on the local WhatsApp group, though Moltoni’s was fairly quickly ruled out on call. The following morning, Dougy Wright found another or refound the same Subalpine Warbler in Soapy Cove, about 500m further north, keeping the discussion very much alive.

Given all that, I thought it was worth putting together a write-up on how to sort these things out — and what I personally reckon these birds were. Spoiler alert: I'm still not completely sure whether the Soapy Cove bird was the same individual as the Kynance bird or what it was, but I’m pretty confident the Kynance bird was an Eastern cantillans, probably a 2CY. On balance I think the soapy bird was also eastern and probably the same bird.

Subalpine Warbler, Kynance Gate 2nd May 2025. Dave Collins

Identifying subalpine warblers

Taxonomy

Nowadays there are five recognised distinct clades, comprising three species of what used to be good old-fashioned Subalpine Warbler. 'Western' (Sylvia iberiae) includes birds breeding in North Africa, mainland Iberia, southern France, and the far west of Italy. 'Eastern' comprises both S. cantillans cantillans, breeding in central and southern Italy, and S. c. albistriata, breeding in Greece and western Turkey. Moltoni's (Sylvia subalpina) appears to form two quite distinct clades, with birds in northern Italy genetically distinct from those on the Balearics, Corsica, and Sardinia. Inornata has been lumped with iberiae, as they don’t seem to differ much genetically.

You can read a lot more about the taxonomy and history of it here and here, including why Moltoni's is subalpina (basically because Latin names follow type speciments and they keep finding that the original type specimens for subalpine are actually Moltoni's)

The original Svenson (2013) map. It has now been suggested inornata be lumped with iberiae and the island populations are subalpina are a bit distinct from those in the north of Italy

Latest phylogeny of subalpine warblers - see this page for details.

Telling them apart by looking at them

The Collin's guide isn't too helpful with subalps, as it doesn't distinguish between the two forms of eastern, which are actually quite different from one another (though I suspect they'll sort this out if a new issue emerges). It's usually Eastern cantillans and Western that are the source of confusion. Anything other than a an adult male in breeding plumage is also a bit of a headache, though tail pattern and primary projection can be useful. I'll stick mostly with adult males. You can read more about females and other ages here.

General tones and submoustachial

Western Subalpine Warbler. The underparts tend to be extensively warm orange-red, almost brikc-coloured. A key feature to look for is the lack of contrast between the throat/breast and the rest of the underparts. They usually have a short and narrow white submoustachial. This one here is an absolutely classic western.

The bird below, found by Tony and Dougy at Soapy Cove in 2021 is also a classic western.

Western Subalpine Warbler, Soapy Cove, 6th Apr 2021. Photo: Joe Jones.

cantillans Eastern. The underparts are more often rather more pink-toned than in western - rarey orange brick toned. The darker throat tends to contrast more with a paler under belly, but note that the flanks can be more concolourous with the breast, but there is almost always some contrast between the flanks and the breast. Below are a couple of photos of a vagrant cantillans I found in Mallorca, which ran the guantlet of the Spanish experts, when submitted.

The bird below, found and photographed by Tony Blunden along the Kynance Road area on 13th Apr 2015 is also probably a cantillans Eastern. Note the broad white submoustachial and flanks contrasting with the throat.

albistriata Eastern. Classic individuals are actually fairly easy to identify, The belly is much more extensively white, with darker redish tones confined to the throat. The flanks and upper belly tend to only have a hint of reddish-pink wash to them. The bird below, found and photographed by Tony in his garden looks to be a classic albistriata.

Moltoni's. These tend to have more extensively salmon-pink or rose-pink underparts, lacking the contrast between the throat/breast and the rest of the underparts seen in cantillans Eastern, but more pinkish in tone than western. The submoustachial is normally short though can be variable in breadth, They are tricky to identify conclusively on plumage, and the best way to identify them is on call (see below). The bird below, seen and photographed by Tony along the Kynance Road on 9th May 2016 seems like a very good candiate, but wasn't heard unfortunately.

This one from Corsica is a definate Moltoni's

Classic males of all taxa in spring seem pretty straightforward, and it is a good starting point to ask, which of these does it look like? The trouble is that there does seem to be a bit of variation, and 2cy year males tend to be a bit more faded, such that a western might look more like an eastern. It's tricky to age them too: 2cy do tend to show a slightly more brown iris, and often retain some worn juvenile tertials and tail feathers, and often the white pattern isn't as fully developed, but in general they are hard to age in the field. Then, of course, there's the issue of females and non-breeding males. The following are more reliable then.

White on the tail

According to Svennson, this is the sure fire way to identify them (though see note on sub-adults below). Put simply, both forms of eastern have a thin white wedge that extends down the shaft of T5, whereas western and Moltoni's have a square white tip on T5. This is true of both males and females and many 1CYs (see simplifed diagram below). If you subscribe to British Birds, you can get the full article here.

In more detail:

Western. This has a usually small and basically square white tip to T5 in adults of both sexes and often also in first-years. If anything,Western Subalpine has on average more white on T6 than Moltoni’s Warbler, with the extent of white similar to Eastern Subalpine. White tips on T5 and T4 average slightly more extensive in birds from north Africa, but there is much overlap.

Eastern (both cantillans and albistriata). The tail patterns are very similar in both with between-individual variation exceeding the difference between the two taxa. Both show a narrow white wedge inside shaft of T5, present in adults of both sexes and often also in first-years. The size and number of wedges on the outer tail feathers varies somewhat individually, some having quite a small wedge on T5 only, others a very extensive wedge on T5 and smaller wedges also on T4 and T3. Juveniles and first-winters with retained outer tail feathers have either a diffuse hint of a wedge or none at all.

Moltoni's. As in western, the white tip on T5 is small and basically square white tip, or occasionally bluntly wedge-shaped. This is the case in adults of both sexes and often also in first-year birds. They typically have less extensive white on T6 compared with both Western and Eastern Subalpine Warblers, often with white restricted to edges and tip (but variable and some overlap in this character).

Unfortunately, the tail method — once thought reliable — isn’t 100% failsafe, except in full adults. Many 1CY birds don’t yet show a fully developed white tail pattern. They undergo only a partial post-juvenile moult and typically retain their juvenile tail feathers through autumn and winter. While most complete their moult on the wintering grounds between December and February, some 2CY birds still lack fully developed tail patterning even by May. This can lead to confusion — for example, see this bird with a western-type tail that proved to be eastern. The most likely explanation is that, as a 2CY, it hadn’t yet developed its full tail markings. Also, unless you're handling the bird or have high-quality photos, tail patterns can be hard to assess. When using photos, make sure you can see all six rectrices on each side — it's easy to misidentify, say, T4 as T5 if T6 is tucked beneath.

Primary projection

A recent paper available here Andrea Corso et al show that primary projection can be a very useful feature. Eastern Subalpine (both cantillans and albistriata) shows narrow and long primary projection, with six to seven visible and well-spaced primaries visible. The projection on cantillans is on average slightly longer than on albistriata. By contrast, Western Subalpine shows shorter and broader primary projection formed by five or six unevenly spaced primaries. The differences are valid across age and sex. Moltoni’s, typically has intermediate primary projection, which some suggestion that primary projection on Corsica and Sardinia is on average slightly longer than those from Italy. However, while usueful, it isn't known whether primary projection is completely diagnostic.

Telling them apart by listening to them

Song. Spring males are often quite vocal and there are a good selection of songs available. Here, here, here and here are some examples of Western. Here, here, here and here are some examples of cantillans Eastern. Here, here, here and here are some examples of albistriata Eastern. Here, here, here and here are some examples of Moltoni's.

The songs are superficially similar and show a degree of individual variation. That said, Western sounds scratchier to my ear, with fewer low-pitched, whistling notes — more reminiscent of a Linnet. Eastern cantillans and albistriata are virtually indistinguishable, but both differ subtly yet distinctly from Western, with more frequent flutier, higher-pitchednotes that are a bit more reminsicent of a Serin. Moltoni’s is trickier still — falling somewhere between the two.

Songograms again reveal some subtle but important differeences - typically the vertical lines - the scratchy notes are more dominant on western, whereas in eastern there are more squiggles indicative of the more frequent fluty notes.

Calls. Calls are a sure fire way of seperating some of the taxa. Western has a hard tack like a Lesser Whitethroat (listen here). Eastern cantillans is very similar to western (listen here) but is more of a teck, and very sligthly softer. Eastern albistriata actually has a completely different call from cantillans - a t-tret t-tret sound (listen here). Moltoni's is also diagnostic on call - a soft wren'like trilling sound (listen here). There's a nice side-by-side of the spectograms of each taxa here: https://luscinia61.com/2022/04

The Lizard bird

Appearance. The bird fits all the features of a cantillans eastern. The flanks contast with the darker throat, a fairly broad moustachial stripe (top). The primaries are pointy (see middle photo) with at least six visible, and the there does appear to be a fairly distinct white wedge in at least one of the feathers that isn't the outer (bottom photo). So is it that straightforward. Probably, more or less, but a couple of small flies in the ointment (see below)

Subalpine Warbler, Kynance, Dave Collins

Blow-up and slightly enhanced image of the primaries. Comparing with the figures shown in this paper, it would seem to fit eastern much better than western

Blow-up and slightly enhanced image of the tail

First, there is another photo (below) that shows the tail when the bird in flight, which appears to show quite a square white end to T5, which at face value is pretty damming evidence. It also suggests the tail is quite worn, which coupled with the brownish iris might suggest a 2CY bird rather than a full adult, where western can look a bit more eastern.

Subalpine Warbler in flight. Photo: Joe Jones.

It is hard to be sure what is going on, but two points are worth noting. First, it is quite hard to see which tail feather is which on the flight photo. There are only appears to be five showing on the left-hand-side, when a fully spread tail would show six on each side. Is is just about possible that T6 is actually tucked underneath T5 and is the square tipped one T4? Second, and probably the more likely explanation (thanks partiocularly to Nick Watmaugh for pointing this out), if the outermost tail feather is not tucked underneath T5, then T6 does not look like a classic adult Eastern or Western where T6 which should have extensive white on both webs. However, on some sub-adult birds the white pattern on T6 and T5 may not be fully developed. You can see this on several photos in the Svensson article but a particularly extreme case is a female found at Spurn on 312st May 2020, shown below. Beth Clyne's photo shows what quite clearly appears to be a western-like tail pattern, but the bird was actually DNA-identified as Eastern. On Joe's photo, it also looks quite like the extent of white hasn't full;y developed, and is a good explanation for why it doesn't quite seem to tally with Dave Collin's photo - if it is quite faded, it is more likely to be visible on some photos than on others.

Vocals. Both the song and the call of both the Kynance and Soapy Cove bird were recoded, but just on a mobile phone so the calls are not very clear. Here is the song of the Kynance bird and here is the song of the Soapy Cove bird. The Kynance bird is very fluty, whereas the Soapy Cove bird has more of the scratchy notes, but both, to my ear, have enough high-pitched fluty notes to make them fit more squarly in the eastern than the western camp, especially the former. The sonograms would seem to bear this out too. Note the clips are shorter than in the sonograms shown above, so the lines are fatter.

Sonogarms of Lizard Subalpine Warbler. There seems to be just enough horizontal squiggles in the Soapy bird to fit eastern. The Kynance bird is entirely inconsistent with western

Call. The calls of the Kynance and Soapy bird are available here (Kynance) and here (Soapy). Both seem to seem nearly identical and seem to match eastern cantillans very closely, being slightly softer and having more of a 'teck' than the harsher 'tack' of a typical western call. Both emphatically rule out Moltoni's and eastern albistriata.

Conclusions

I personally think that, despite the one in-flight tail shot, there is enough convincing evidence to ascribe the the Kynance bird to Sylvia cantillans cantillans (Eastern), very likely a 2CY. Nobody saw the Soapy bird well, but the calls and song are more indicative of eastern, albeit the song less conclusively so. It may have been the same bird as the Kynance bird, but it behaved quite differently and tended to give sub-song rather than full song and there is precident for multiple subalpine warblers turning up on the same day on the Lizard. It probably was the sdame bird. Whether ti definately was will remain a mystery.