Caspian Stonechat ssp variegatus on Vlieland

 

Deception Birding!

by Nils

21 years ago, Hans ter Haar († 2011) invented a new way of rarity hunting in the Netherlands. After years of the classic Dutch Birding (whole) weeks on Texel in October, his eyes got stuck on Vlieland. Vlieland, next to Texel, was much narrower, almost wholly accessible and much smaller than Texel. So, it looks much better to cover with a fairly small group of birders. Also he thought that one full week was not the way; too much chance for a long slow period and too much chance of ‘the same birds’ every year. No, the plan was three long weekends spread out over the autumn between early Sept and late Oct. With not too much expectations but with humour and some self-mockery, Hans and his friends called their experiment ‘Deception Tours’. http://deceptiontours.nl/

Indeed some weekends were a deception (motivations were always high, but birds sometimes few), as on all island which lean on migration, but the concept was brilliant! The list of rarities found during the Deception Tours weekends is much too long to mention here, but to highlight a few: 5 new species/taxa for the Netherlands (Yellow-rumped Warbler, Turkestan Shrike, Pallid Swift, Northern Waterthrush and indeed Caspian Stonechat). The 2nd Bonelli’s Eagle for the Netherlands, and Vlieland, as small as it is, now host about half or more of all Dutch records of Olive-backed Pipit (7 in one weekend of which a group of 4!), Yellow-breasted Buntings, Rustic Buntings and Radde’s Warblers (4 on one day!). Hans sadly died just before the third weekend last year. Until his last days, although already very weak, he still supported us on Vlieland by phone. His motivation, insights, leadership and great company we will continue to miss.

In the overcrowded Netherlands, Vlieland is the most ‘remote’ inhabited island. It has a population of 1100 people and the ferry arrives just three times a day. UK birders will be laughing now, and yes we can only dream about isles like Fair Isle, Foula, St Kilda etc. Cars are not allowed for visitors on Vlieland, so birding goes by bike and by foot.

The mobile network doesn’t cover whole Vlieland so if you come across this without receiving the message earlier, you know there is sometimes very wrong (uhh, good!).
The Northern Waterthrush twitch, Sept 2010
Photo by Henk van Rijswijk

October 2012

The weather maps are my compass. After quite a long period of bad situations, finally a narrow ridge of high pressure waved over Southern Scandinavia during the second Deception Tours weekend (5th -7th Oct). On Saturday early morning the back of a frontal zone passed Vlieland and already huge numbers of thrushes, mostly Redwings were coming in while still raining. The excitement in the air sunk quickly down into our veins, our team prepared for code red…

For me and my friends, the fall phenomena is a wonderful event in itself, whatever including rarities or not. But the excitement went to a climax when Eddy Nieuwstraten and Han Zevenhuizen bumped into a Siberian type Stonechat with white in the tail… A ring from Han and within minutes I was with them: WOOOOW a cracking male variegatus!! Beside the ‘black-eared wheatear-tail-pattern’ the bird shows • a huge whitish (not uniform buffish) uppertail-coverts and rump-area, • very broad orange neck-side patch, strongly narrowing the black mask towards the rear-side • sandy-grey fringes to the mantle-feathers and scapulars, and • an almost maximum contrast between black underwing-coverts and white bases of the underside of the flight-feathers (latter from photo’s). All spot-on for variegatus.

In flight the bird gives a very pied impression…
Photo by finder Han Zevenhuizen

The bird was a splendid male with such a deep black face, seemingly full set of adult-type wing-coverts, narrowly pale edged primary-coverts and blackish primaries that, at first I thought it have to be an adult male. I knew that at least some first winter males variegatus are much more ‘adult-like’ than maurus first winter males, but this seems too much.

In the 2nd part, below, the ageing of this beauty is further clarified. The earlier presumed age as a first winter by the presumed diagnostic tail-feather shape appeared to be incorrect.

Note the nasty swellings at the tarsi and toes, which probably also effected the leg-coloration.
Photo by Eric Menkveld

The taxonomic situation of variegatus is still unclear, but for the time being widely regarded as a form of Siberian Stonechat and forms a group with armenicus: the Caspian Stonechat. Whatever future DNA studies will discover, for birders, the males are very distinctive by at least their tail-pattern. I think the most interesting thing is that first winter males variegatus in autumn are often already much more ‘male-like’ compared to first winter male maurus (which are often hard to tell from females). To highlight some possible reasons for this: • a difference in body moult-strategy between the two taxa (with maurus acquire a black mask by moult not before the winter)? • larger pale tips to the body-feathers of maurus, concealing the male-like plumage tracks? and/or • earlier breeding season of variegatus (due to the more southern breeding range) resulting in older first winter birds which are more advanced and thus more ‘adult-like’? As far as I know, this is not clear, and some first winter male variegatus are much less advanced and thus more similar in body-plumage to maurus. Maybe there are readers who know more? The Vlieland-bird had already moulted most or all wing-coverts, some secondaries and possible the upper two tertials. Also several secondaries went missing during its two week stay, maybe due to active moult. The more adult male-like plumage compared to most vagrant (first winter) maurus in Western Europe in itself seemed to be an interesting starting point for future discoveries, before the tail-pattern is seen. Females are, as far as I know, identical to maurus (females). Maybe some show little pale at the base of the outer-tail feathers, normally invisible in the field.

Part 2: Caspian Stonechat on Vlieland, the ageing reviewed

Thanks to Magnus Hellström, Tom van de Have and Brian Small, now we can firmly say that it is indeed an adult (2cy+).

Very pointed tail-feathers with large white tips; incorrectly thought by me (Nils) to exclude an adult, despite the otherwise very ad-like appearance.
Photo by Arnoud van den Berg

Magnus Hellström: tail of fresh adult autumn (2cy+) male stejnegeri, Beidaihe, China September 2012. Although there are some average differences regarding the shape of the tail-feathers, both age classes (1cy and 2cy+) shows quite broad feathers with a rather protruding and pointed tip. Note also the pattern/coloration: in average, adults generally show a darker black feather with a pale tip/edge that is whiter and more sharply set off. In juvenile males the feathers are usually more brownish black with a tip/edge that is more buffish and often more diffusely set off.
Photo credits: Beidaihe Bird Observatory.

 
 

Here, the primary coverts are visible and show to have only a very narrow fringe which is even more narrow along the tip. In first winters the fringe should be thicker, often more frayed and most thick along the tip.
Note also the adult-type wing-coverts with white fringes which not reach the base of the feather. Well advanced first winters could show at least some adult-type coverts.
Photo by Cock Reijnders

Here the uniform and deep black face is well visible; typical of adult males form the ‘redstart/wheatear-group’ in autumn. First winters are more extensive pale tipped including the loral area.
Photo by Marijn van Oss

 

 

 

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4 Responses to Caspian Stonechat ssp variegatus on Vlieland

  1. Tom van der Have says:

    @ Nils: I think this bird showed several other adult characters: jet black primaries (same colour as tail feathers) and a narrow white margin to the primary coverts. Unfortunately, the latter character is concealed by the body feathers in the above picture! Furthermore, the inner tail feathers were unmoulted and the left outer tail feather (t6) was still growing. Such an advanced tail moult stage seems unlikely to me to occur in 1st winter birds. The moult strategy in several Saxicola taxa has been studied in depth, including breeding and hybridisation studies. Maurus is exceptional compared to rubicola and African taxa that it produces only one clutch and has a very early moult. If this applies also to variegatus (one clutch, early moult) then indeed a more advanced moult stage would be expected in autumn if it breeds earlier than maurus. The maurus population in Kazakhstan apparently also has some white at the basis of the tail feathers, but this is usually concealed by the upper tail coverts.

  2. Brian S says:

    Hi Nils. I too think this is at least a 2cy+ male (adult), for the reasons Tom states, but also something simple like the all black loral feathers that would have pale tips in 1-w male – http://nubijar.blogspot.co.uk/2011/11/casucasian-stonechats.html . Greta bird and very jealous.

  3. nilsvanduivendijk says:

    Hi Tom and Brian,
    The main problem not to call this an adult was the shape of the tail-feathers, which maid me and several others believe that this is ‘diagnostic’ for a first winter, despite indeed the rather overwhelming things suggesting otherwise. Beside your input, Magnus Hellström send us a very useful email in which he also questioned the age as first winter, and he also wrote that at least some adult stejnegeri have the same pointed tail-feather shape as the Vlieland-bird.

    Also the borders between the black and white parts in the tail of the Vlieland-bird are sharp, while in the first winter bird in the link towards Yoav’s blog (thanks Brain!) shows diffuse borders.
    All in all, this put everything into its place.

    Thanks you very much to have you involved here!

  4. Pingback: Stejneger’s Stonechat in the Netherlands? | Birding Frontiers

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