Discovery, Confusion, Fascination and Mystery (all rolled into one)
(a Magnus Robb and Martin Garner production -because without Magnus , MG would be stumped!)
1st winter flava Wagtail. Canal Scrape, Spurn 24th August 2010. What are the origins of this rasping flava?
What follows is an example of the start of a process – of discovery. It usually begins with some field experience which leaves me with more answers than questions, but especially intrigue. This has been a tricky post to write, because I think the stuff I don’t know is greater than that which I do know. It makes me nervous! No quick or easy answers (here at least) – more a journey of discovery. In case you’re interested, here’s a little diary of how the process began and what I am learning…
The Point Dunes, Spurn. 17th August 2010. 2 days earlier a 1st winter Citrine Wagtail was only the second record for Spurn and the first in autumn. With good numbers of flava wagtails passing down the Spurn peninsula over several days I (MG) made a regular effort to check grounded flocks. One such was a group of about 12 birds at the point, early on 17thAugust. They were tricky to see in the marram grass and flushed easily. My attention was quickly arrested by a clear rasping Citrine-like call coming from one bird. I managed brief, poor views. Nevertheless they were enough to satisfy me that it was not the first winter Citrine of 2 days earlier, nor (I surmised) a less advance juvenile Citrine. In fact it looked like a fairly typical moulting juvenile- first winter flava -type. Clean breasted but still with something of dark supraloral line. I radioed out that I had a rasping flava wagtail – not Citrine- though I confessed I had no working knowledge of Citrine Wagtail in ‘proper’ juvenile plumage.
Intrigued I tried to relocate the bird as the flock blogged about. I finally got within reasonable range, and slightly isolated from the rest of the group found the bird to be giving both the raspy-type call (which at the time sounding scarily Citrine-like) seemingly mixed with more normal sounding flava type calls. I managed some poor sound recordings before the bird flew on. I returned an hour later in an effort to get better views and attempt to photograph it, but no luck.
PS Discovered subsequently that Pete Wragg encountered almost certainly the same bird the previous day. On 16th August he described a flava wagtail – which flew over him several times give obvious raspy calls but seemingly also giving normal ‘flava– type calls. His impression of the bird on brief views was that it was not a Citrine but fell into ‘young flava’ camp.
Sat 21st August. Birdfair, Rutland. Chatted with Magnus, mentioned the rasping flavas. He encouraged me to send recordings.
P.S. I use a Remembird device for recording- more details on that and making sonagrams on the Equipment page http://birdingfrontiers.com/equipment/
Canal Scrape, Spurn 24th August 2010. After a morning down the point called by en route back to caravan about 9:30 am to find 4 close feeding flava wagtails. One quite striking bird had strongly greyish tones to the upperparts. It too uttered an obvious rasping call on several occasions. Feeling somewhat indifferent with my confusing experience of rasping flavas I nevertheless took some photos and sound recordings (force 5+SW blowing straight into hide) before heading for breakfast. Was it the same as the bird 1 week earlier at the point. Maybe? I really don’t know.
1st winter flava Wagtail. Canal Scrape, Spurn 24th August 2010. Giving rasping citreolla-like calls combined with some ‘eastern’ plumage characters. What’s it doing at Spurn in August? Where’s it from?
Laptop, Caravan, Spurn. 29th August 2010 Magnus emails. Shocking news! Read on:
“I’ve had a listen to your wagtail sound [from Point Dunes on 17th August] and taken the liberty of cleaning it up a bit. I can’t remember how well you saw the bird, but I’ll just tell you what I think it sounds like. For me it falls squarely in the ‘Citrine camp’, and cannot be one of the rasping southern taxa: feldegg, iberiae or cinereocapilla. This is because it is too high-pitched, not coarse enough, and it lacks the details I mentioned, that I can see on sonagrams of those taxa. I don’t suppose you’d mind if it was a Citrine, but I think you mentioned it looked more like a Yellow Wag of some kind…
There are several other taxa that call like Citrine (and not like feldegg), but all are from quite far east. They are basically all members of the ‘eastern yellow wagtail’ group which also includes Citrine; e.g, tschutschensis, taivana etc as well as thunbergi-lookalikes from north-central Siberia that pass through Kazakhstan in spring. However, what are the chances of one of these turning up in mid-August? Most claims are from quite late in the autumn.”
Bewilderment now replaced indifference. Over next few days all recordings from the Point Dunes and Canal Scrape encounters were reviewed and Magnus confirmed ‘citreola-type’ calls from both. (N.B. we use “citreola –type” to refer to the very similar calls of Citrine Wagtails and Eastern Yellow Wagtail group.) We have not yet arrived at a full explanation. Nevertheless we have discovered some fascinating stuff. Here is what we have:
To help put the interesting calls in context here is a quick overview of the normal variation of the calls of Yellow Wagtails heard in Britain, most of which are assumed to be ssp. flavissima.
Breeding season song and calls
During summer months, adult breeding Yellow Wagtails of the (north) western group (flavissima, flava, thunbergi etc) utter a raspy sounding song. This is also often accompanied by raspy calls, which can be uttered in flight and presumably include the ‘alarm call’ – also a phenomena of the breeding season. These can give us a fright, but are not really similar to either citreola-type or feldegg-type rasping flight calls.
Yellow Wagtails (flavissima, flava, thunbergi) utter a variety of calls, quieter or louder and include an occasional slight rrrr component. Its even possible that all Yellow Wagtail taxa have some element of modulation (varying up and down in frequency) in their flight calls, but it is so tightly spaced in the calls of flavissima, flava and thunbergi as to be imperceptible. Thus, degrees of coarse versus fine. While this call can be described as rasping, it is weak and rather short and not nearly as impressive sounding as a typically ‘electric’ citreola – type call.
Yellow Wagtail, Point Dunes, Spurn 17th August 2010. This is the familiar ‘sweet’ sounding call of Yellow Wagtail in Britain (presumed flavissima/ flava/ thunbergi). Note how the 2nd part of the sonagram is of a thicker downward angled straight line with no visible modulation.
Click on the sonagrams to see them better
Sonagram of adult male flavissima. Point Dunes, Spurn 17th August 2010. Showing short weak rasping call type amongst normal ‘sweet’ calls. See how there is slight modulation, but the call is not very long. Click on the sonagram
Sonagram from Encounter 1 of rasping flava, Point Dunes, Spurn, 17th August 2010. M Garner. Deep, well spaced ‘slower’ modulation over longer time period is what produces a proper rasping call . The recording has not picked up the finer details and harmonics of other sonagrams presented here due to less expensive equipment, greater distance from the bird and some wind noise. The basic ingredients are nevertheless visible.
Following sonograms to compare with other individuals and taxa:
These 2 sonagrams are from a recording of a typical October, grey and white, presumed ‘Eastern Yellow Wagtail’, Netherlands, 13th October 2008. Herman van Oosten
The call both audibly and on the sonagram is very similar/ almost identical to the Point Dunes bird of 17th August. Interestingly in the lower sonagram, the 3rd call is audibly more like the normal ‘sweet’ call flava/flavissima/thunbergi and the sonagram is similarly ‘straight- edged’ lacking visible modulation.
Black-headed Wagtail (ssp. feldegg) SW Turkey, 19th August 2009. Martin Garner
‘feldegg’ has the most widely spaced, slowest modulation producing the most rasping call of all the flava/citreola groups. Seeing a rasping flava doesn’t really mean very much (its a bit like seeing a ‘Commic’ Tern). Get a recording – get an identification!
Presumed 1st winter North-eastern flava wagtail, Canal Scrape, Spurn, 24th August 2010
1st winter North (or South)- eastern Yellow Wagtail, Pulau Burung, Malaysia 23rd September 2007. David Bakewell. About 90% of identifiable birds here are tschutschensis, then plexa/macronyx (c10%) and taivana (rare). ‘Dig Deep’ is David’s blog and it’s a cracker! http://digdeep1962.blogspot.com/
Some observations, comments and hypothesis about what’s going on:
- one or more young flava-type wagtails giving a rasping call which best fits with citreola/ eastern flava (closest to Eastern flava group) on Britain’s east coast in August.
- Calls are very similar to an October grey and white flava seen in the Netherlands (which is considered to be vagrant ‘Eastern’)
- Citrine/ flava hybrid option explored but at the moment, unconvincing. Very few real Citrine plumage characters on Spurn bird(s).
- Plumage characters of (some) young Eastern flava are crystallized a little more. Features such as:
1) Cold grey tone to upperparts, with quiet bright mossy-green fringes when fresh
2) Tendency to extensively or wholly dark ear coverts
3) White (ish) supercilium and throat
4) Most of underparts white with little yellow (restricted to lower belly/ventral region) or complete absence of yellow (classic ‘grey and white flava’)
5) Can show quite white (sometimes broad) fringes to retained juvenile wing bars and tertials
6) Adult females with more male-like plumage than western taxa
Eastern Yellow Wagtails: What about plexa of Central and East Siberia? This form is provisionally synonymised as ‘eastern thunbergi’ – “following Meinertzhagen (1954) and Vaurie (1957)” in Alstrom and Mild’s ‘Pipits and Wagtails’ book. The calls of plexa do seem to link it better with the Eastern Yellow Wagtail group.
Why do migrant watchers in East Yorkshire and Norfolk report a rasping quality to the call of some thunbergi? These reports do NOT concur with sound recordings of western thunbergi. Are they instead birds coming from plexa population(s)?
Most compelling and revealing information is found in this phyllogenetic study:
Key points: “If recognized as species, the name Motacilla flava applies to western forms, the northeastern group becomes Motacilla tschutschensis (Gmelin 1789) [with subspecies plexa and tschutschensis], and the southeastern group is Motacilla taivana (Swinhoe 1863).”
Examples of plexa were sampled as NEAR to Britain as Yamal on the edge of European Russia. Thus vagrant plexa reaching Britain may be no further away than the northern Urals/ edge of the West Siberian Plain. It could be argued that the Citrine Wagtail that turned at Spurn, around the same time was from the same geographic region.
Furthermore BWP notes that in the USSR, the northernmost birds leave breeding grounds from early August, making vagrancy on Britain’s east coast during August an eminent possibility. Presumably individuals from further east across the considerable plexa/ tschutschensis range could occur in Britain, later in the autumn as is more normally expected.
More to be discovered here me thinks! Let me know if you see a potential ‘North-eastern’ flava – and whatever you do? Record the call!