Patchwork 2010 - Bittern on six fingers

Bittern, SNR, 21st December 2010

Number one in a series of boredom-relieving, reasons-to-believe-in local patch highlights from last year. Of course, all these and many more occur 'live' over at the Hackney Wildlife latest sightings page, but while pickings are slim there's no harm in isolating a few special occasions to remind myself why masochism is nothing to be ashamed of.

For those unfamiliar with the patch (and my endless ramblings about it online and elsewhere), Stoke Newington Reservoirs comprises two very small waterbodies deep within the dark heart of urban London, in the Borough of Hackney. A full overview can be found here.

Last year was particularly memorable, not least because I was able to cover the patch on something approaching 300 days, and with greater scrutiny than ever. Hence, a golden opportunity to nail often-dreamed of and unexpected species that would otherwise drift through unnoticed.


Bittern, SNR, 7th January 2010

Bitterns have become something of a star bird here in the last two winters; unthinkable previously, especially considering the miniscule amount of suitable habitat and unappealing location. Unrecorded in the area since the first record of a bird found in a Stoke Newington bus shelter in the infamous '62/'63 winter (admirable local knowledge perhaps, what with no tube station locally), 2009 provided the first modern record, watched from the Obs platform lolloping west at dusk on 28th October. At the time, exceptional, and a welcome addition to the personal list.

Until sustained coverage during the extended cold snap in January 2010 brought an amazing spectacle on the 7th: Coming in low from the east at around 1340 and maniacally harassed by a group of Carrion Crows, the bird looked to put down in the reedbed, but was recieving too much hassle; instead of continuing west (like the first site record above), the Bittern opted to swing around and land in the crown of a tree on the Woodberry Down housing estate.


Visible from my office window and garden, it remained in the treetop for at least ten minutes, defending itself admirably against a group of about 15 Carrion Crows and three Magpies. Despite constant attack, it managed to aim a potentially mortal blow at one of the crows, which tumbled out of sight....








Bittern, SNR, 7th January 2010

Fast-forward to March, and the first morning scan of the East Res revealed a suspicious movement in the reedbed on the far side; soon enough revealed to be another Bittern, the first actually seen utilising our Phragmites, and the first to be twitchable by other local birders (including the Birdwatch office - see Dominic's blog entry here).

Less than two weeks later, and a wander round the East Res perimeter produced yet another - a new bird (on flight feathers) flushed from close range on March 13th. Number four for the site, all in the same winter.

And so to this winter, and the idea of an extended period of freezing conditions bringing in a stellaris suddenly not sounding so foolish. After a fantastic week of weather-related scarcities and movements (Greenshank, Curlew, Jack Snipe, two Goldeneyes etc - all gold dust locally), December 6th brought Bittern number five - flushed by a fox, at close range, in the south-east corner of the reedbed.

A period of milder weather returned conditions, and sightings, to regulation mid-winter fare in the meantime; until a second period of severe, extended arctic conditions set in from the 17th - and bingo, another Bittern. Number six was watched drifting in from the south at low level, croaking noisily (not unlike a Brent Goose), and sensibly putting down into the reedbed before risking being taken out by the local Corvus / Larus hit-squads.



Bittern, SNR, 17th December 2010

Two days later and with the big freeze becoming even more extreme, presumably the same bird was initially flushed from the East Res perimeter on the morning of the 19th, and was later watched playing cat and mouse with the local foxes during the middle of the day from the epic panorama of the Lincoln Court rooftop.



Bittern, SNR, 19th December 2010 (from the roof of a neighbouring tower block)

The following day, and after watching the bird's behavioural patterns (commuting between the inflow and outflow much of the time), I relocated it by the outflow. With the light good, snow and ice coating everything in sight and camera at hand, I crept up on the Bittern - and instead of flushing as expected, it adopted the snake-necked camouflage mode, and both of us froze.





Bittern, SNR, 20th December 2010

Allowing approach down to about four metres (any closer and the camera lens impotent), the bird performed beautifully, under the impression it remained cleverly undetected... I left it in the same spot after five minutes or so, still neck-craning and immobile. Staying untill 22nd at least, it represents a wonderful part of local birding - from fantasy pipe-dream to eagerly expected in little more than a year.





Bittern, SNR, 21st December 2010

ID hell, episode four - another SNR Gull, December 2010

Another one from the local patch (Stoke Newington Reservoirs), from a couple of weeks ago, on 28th December 2010; found amongst a large build-up of the commoner gull species on the ice of the East Reservoir, quite late in the day and in overcast, dull (and very cold) conditions.



At some distance (the short films here are with the scope at 60x and a hand-held pocket digital camera at full zoom), the bird still stood out conspicuously. Confusing features included:

overall size and shape - slightly smaller than nearby Lesser Black-backed Gulls, with a lower carriage; probably also slightly sleeker and less bulky than e.g. graellsii;

head - relatively small and fairly rounded, with a gentle hind-crown peak; dark streaking intense immediately around (esp. just behind) the eyes, but otherwise light and inconspicuous

legs - pink; appeared quite short

eye - pale, perhaps yellowish, iris; quite 'mean-looking' despite apparently diminutive features

bill - also appeared quite short, almost blunt, with little gonydeal angle; yellow with large red gonys spot

Upperparts - mid/dark grey, darker than e.g. argentatus and michahellis (and slightly darker than Common Gull); clearly paler than graellsii

wing detail - the most striking feature in the first instance and throughout - very extensive white primary tips, which formed an almost unbroken white line along closed primaries from a distance; large white tip to p10, seperated from large white mirror by a small dark band; extensive white trailing edges to remiges; large, extensively white tertial step





After a bit of research on and offline, I'm still unable to find anything like a worthy mast to pin its colours to. Comments, as usual, welcome.

ID hell, episode three - putative eastern Lesser Whitethroat, St. Agnes, October 2010

Last autumn's excellent fortnight deliberately marooned on Agnes produced plenty of great birding, migrants of quality and quantity, hatfuls of scarcities and a handful of rarities, as well as a few near-misses and subspecific questions; of the latter, this Lesser Whitethroat was particularly interesting.

First located on the morning of the 10th, I refound it a few hours later nearby, at the seaward end of Barnaby Lane (around the gate onto Wingletang). In truth, hard to miss, being particularly bullish in character and needing no excuse to hassle the hell out of nearby Wrens and Robins.


The bird initially frequented the last (southernmost) Pittosporum hedge, before a little gentle pishing persuaded it over into the bracken- and bramble-covered dry stone wall at the end of the lane, and to within a few metres distance at times.

Aware of the possibility of halimodendri and other eastern races - especially with a perfect supporting cast (a mammoth fall of passerines including Black-headed Bunting, dozens of Ring Ouzels, Rosefinch, RB Flys, Wrynecks etc., and Black-eared and Pied Wheatears just across the water on Mary's) - I naturally spent a good while with it, taking plenty of notes and photographs. Location, timing and and prevailing conditions (south-easterlies, weather fronts, birds arriving in waves) hardly diminish the bird's credentials.


Thankfully a few of the record shots came out quite passably despite the poor light, and the interesting features are self-evident on the accompanying photos. Of these, the following were most noticeable:

> pale, sandy/rufous-brown upperparts, extending well up onto the nape
> extensive white in the outer-tail feathers
> much reduced dark 'mask', with contrast barely evident from most angles; only a small area of the lores noticeably darker
> entirely pale tertials, concolourous (or slightly paler) than the mantle

.... a suite of characters strongly supportive of an eastern origin, perhaps most likely halimodendri, and a cracking bird. Who needs Dendroicas?

ID hell, episode two - Hackney Hirundine, May 2010

Another one from the local patch, another from last year, and another mystery. Appearing with a mixed flock of (predominantly) Barn Swallows, House Martins and Common Swifts over Stoke Newington Reservoirs on the evening of 11th May, and immediately standing out, the bird apparently shared most characteristics with the Barn Swallows it was hunting insects over the East Res with, except for several obvious differences - most strikingly, its short, squarish, apparently undamaged and symmetrical tail.

Also apparent in good viewing conditions (but often not in poorer light and at distance) was the bird's pale, slightly two-toned partial rump-patch; the upper area of which was a little darker pinkish than the lower area (similar to the rump colouration of e.g. Red-rumped Swallow). The feature was by no means clean-cut or extensive as on e.g. the latter species or House Martin.


Most other features were apparently as Barn Swallow, although the vent / undertail coverts were a shade darker when observed close to, and at times the bird appeared less sleek and more broad winged (although the latter feature may have been a proportional 'trick' associated with the short tail). The bird fed actively over the water (both high and low) and gave good, reasonably close views in overcast conditions.



Possibilities? pure Barn Swallow, and the other regular European hirundines, can be comfortably ruled out, as can (to my knowledge) any other swallows and martin spp.; based on the anomalous features the likelihood of a hybrid of some kind seems very compelling, but of what parentage?



Barn Swallow x House Martin would be the most likely candidate based on known frequency of hybridisation (rare, but relatively well-documented) and the abundance of both species geographically; but a hybrid of these two species surely wouldn't show a short, square tail and a pale rump patch. Of all the photographs and descriptions I can find of this combination, none even come close to the SNR bird.

Opinions were sought from various sources, but no further light was shed; David Sibley, who was kind enough to comment on the bird shortly after, expressed general confusion over its identity, concluding with "there just don't seem to be any likely candidates".

Comments welcome.

ID hell, episode one - SNR Gull, December 2010

Part one in a short series of problematic identification headaches....

Having scanned the gulls on the local patch here at Stoke Newington Reservoirs increasingly of late, and while it's by no means a premium site for Larids (see here for overview), there's been plenty of intrigue to keep the home fires burning. Aside from a succession of colour-ringed birds of the four commoner species, an apparent hybrid Herring x Lesser Black-backed Gull, regular Yellow-legged Gulls and omnipresent argentatus Herring Gulls, a couple of recent individuals have been less than straightforward.



Top of the list presently is this troublesome 'Yellow-legged' Gull, on the East Reservoir on the 14th December. Immediately standing out and looking 'wrong' for e.g. standard michahellis, it was distinctive enough to inspire the seeking of more opinions.

After receiving the views of several larophiles, a satisfactory ID seemed increasingly improbable, with the most popular punt initially being a hybrid with potential 'throwback' characteristics. Other possibilities mentioned but thought unlikely included a 'dwarf' (or exceptionally small) michahellis, or an odd Finnish / north-eastern yellow-legged argentatus.




However, a message from Martin Garner the other day raised a fresh possibility. Martin aligned several key features of the bird with lusitanius Yellow-legged Gull, a comparatively little-researched form from the north-west Iberian coastline, and suggested the Stoke Newington bird looked good for this race.....





Following web links and finding several other useful Spanish and European gull study sites as a consequence, it's becoming increasingly difficult to rule this form out of the equation. Most potently, returning to the Yellow-legged Gull text in Olsen, the (previously unnoticed) small print on lusitanius suddenly jumped out, for a variety of reasons.

Key features of this bird included:

size - smaller than the smallest Lesser Black-backed Gulls (of which a variety were present for direct comparison), and significantly smaller than all nearby Herring Gulls.

shape - distinctly low-carriaged, squat and short-legged (almost bizarrely so). Appeared particularly long-necked when alarmed, and hind quarters slender when relaxed.

head - rounded with a flattish forehead and slight rear-crown peak. Very light streaking on the crown and ear-coverts.

eye - iris pale, yellowish.

bill - proportionately heavy and medium-long, with large red gonys spot extending onto upper mandible.

legs - bright yellow; brighter than most recent winter-plumaged michahellis at the site.

upperparts - medium-dark grey. Obviously darker than argentatus, and darker than 'normal' michahellis (and indeed Common Gull); substantially paler than e.g. paler graellsii.

wing pattern - large white wing tips, and reduced black, on primaries. White mirrors on p9. Reduced black compared to e.g. michahellis extending up primaries (e.g. black not reaching primary coverts on p9). No black at all on p5.






Graellsii, argenteus and 'standard' argentatus are easily excluded, realistically leaving a hybrid, an exceptionally small and aberrantly-plumaged michahellis Yellow-legged Gull, a different race of Yellow-legged Gull, or a different race of Herring Gull.




If it's a hybrid, which is always a possibility (especially with large gulls), then of what? While offspring can show anomalous characteristics not indicative of either parent, and 'throwback' features can appear from much further back in the family line, it still seems like difficult to explain this bird's combined features, not least regarding its structure and primary pattern.

An exceptionally small (female?) michahellis also seems implausible - this wouldn't apparently explain the combination of the bird's primary pattern, distinctive structure, and indeed probably its size; in the photos above and below, the bird is stood to the right of a relatively small graellsii, which is clearly larger (easily visible with the naked eye). For comparison a 'medium' sized graellsii (and Common Gulls) is also to its right in the less cropped photos.




Re: the possibility of a NE European race of 'yellow-legged' Herring Gull being involved - which can have darker mantles also - but as MG points out, would expect to have more white in the primaries, and the size and structure would be at best unusual. (Again, being on a steep learning curve in this realm, I'd appreciate signposting to other relevent references of lesser-known Northern HG races).

Finally, the possibility of the bird being a Yellow-legged Gull of the race lusitanius. There's doubtless more information out there, most likely online, that I'm not yet aware of (and would welcome hearing about), but the following features described by Olsen (in comparison with michahellis) read compellingly:


Generally smaller than michahellis. Heavy-billed with flat forehead, 'snaky' neck, slender hindparts and short legs.

Compared to michahellis shows narrower black markings on p5.

Upperparts generally slightly darker (Kodak greyscale 6.5-8).

White-headed July-Jan or just with scattered dark markings.

Bare parts as michahellis, but generally brighter.

Far from being well-versed in the racial and ID complexities of LWHG's, I'd be interested in the views of those with more knowledge and insight, and comments are welcomed.