Still in there – Slavonian Grebe

One might be forgiven for becoming somewhat blasé about Slavonian Grebes occurring in the County this year. After all, there was the long-stayer which first appeared at Earls Barton GP in late May, quickly relocating to Pitsford Reservoir for a protracted stay north of the causeway into early autumn. This individual was in stunning summer plumage when it arrived but it had moulted into the characteristic black, white and grey plumage of winter by the end of August, shortly after which it disappeared, last being seen there on 11th September.

It, or another, then (re)appeared at Pitsford on 29th October – this time on the ‘big side’, south of the causeway, close to the dam. It was still off the dam at midday today when Clive Bowley captured this super image of it catching and swallowing a Perch.

Slavonian Grebe, Pitsford Res, 25th November 2011 (Clive Bowley)

I don’t envy it having to contend with that über-sharp, spiky dorsal fin! Look at that super-bright, red orbital skin around the eye, a feature which it shares with Black-necked Grebe but which is lacking in winter-plumaged Red-necked Grebe.

Another Slavonian Grebe is currently in residence at Hollowell Reservoir, having been present there since 17th November.

No shortage of ‘Shorties’

This autumn has seen significant arrivals of Short-eared Owls in the UK with many crossing the North Sea from Scandinavia and some even turning up on North Sea gas rigs (as highlighted in the BBC’s Autumnwatch last week) as well as in many parts of the UK. One flew across the road in front my car while I was driving in Hampshire last week and I’ve recently seen them at three sites in Northants which, fortunately, has not missed out. In the past few weeks there have been records from Daventry Country Park, Pitsford Reservoir, Hollowell Reservoir, Polebrook Airfield, Harrington Airfield, Harlestone Heath and Maidwell and any undisturbed area of rough ground or wasteland is surely worth a look. The last two of these sites have consistently held good numbers with the Blueberry Farm complex near Maidwell producing an amazing twelve, which is likely to be a record day count for a single site in the County (let me know if this has been beaten!). They were still present there this evening and continue to prove to be a popular draw for local birders and photographers. Access and viewing is from the track which runs west from Brampton Valley Way below Hanging Houghton to Beck’s Dairy, Cottesbrook. Six have been reported at Harrington Airfield in the past couple of days, although three is the number more usually seen there. Dave Jackson has very kindly supplied some images taken at the latter locality.

Short-eared Owl, Harrington Airfield, November 2011 (Dave Jackson)
Short-eared Owl, Harrington Airfield, November 2011 (Dave Jackson)

Apart from the yellow eyes (orange in Long-eared Owl), the photos show nicely some key features which distinguish Short-eared from Long-eared when viewed distantly, namelyobvious, broad, even tail-barring (diffuse and less conspicuous in Long-eared), white trailing edges to wings and thickly streaked head and chest, which contrasts sharply with unmarked belly.

Cross-billed Great Tit

Chris Payne trapped this Great Tit with a strikingly malformed bill in Greens Norton recently. It was trapped twice and appears to be coping well with its deformity and maintaining its average weight.

Great Tit with crossbill malformation, Greens Norton, October 2011 (Chris Payne)

 

 

 

 

 

 

 

Such deformities have occurred in a number of passerine species and on Flickr, there is a page devoted to photos of Birds with Deformed Bills. Several possible reasons for such

Great Tit with crossbill malformation, Greens Norton, October 2011 (Chris Payne)

deformities have been put forward, including genetic or developmental causes, injury or disease, although agricultural chemicals and pollutants may also play a part. It is believed that while some birds can adjust to their handicap and may feed by turning their heads to one side others apparently starve or are plagued by numerous parasites, such as body lice according to Passerines with deformed bills (Julie Craves).

 

 

Dark-bellied Brent Goose at Clifford Hill

A Dark-bellied Brent Goose has been present with the goose flock on the main barrage lake at Clifford Hill Gravel Pits since Wednesday 2nd November, when it was found by Pete User. A first-winter (white-fringed secondaries and greater coverts and lacking the adult’s white neck patch), this is the only record so far this year of a species which produces just one or two records annually in the County. Late October to early November is the peak time. All previous records are of the dark-bellied race bernicla which breeds in northern Russia and winters on the east and south coasts of Britain. According to Mark Williams, who saw it on Sunday, it appears to have a bit of damage to its right eye and walks with a slight limp so it may stick around for some time yet. Some of my digiscoped pics below.

First-winter Dark-bellied Brent Goose, Clifford Hill GP, November 2011 (Mike Alibone)

There are apparently no local records of the pale-bellied race hrota which breeds in Franz Josef Land, Svalbard, Greenland and northeastern Canada, wintering in northeast England

First-winter Dark-bellied Brent Goose, Clifford Hill GP, November 2011 (Mike Alibone)

and Ireland and considered to be a separate species by a number of authorities. I would love to find one in Northants!

More on ‘Goldpolls’

Following my further attempts to discover the origin of ‘Goldpolls’ Hein Van Grouw (Curator, Bird Group, Department of Zoology at The Natural History Museum, Tring) kindly commented on the Stanford individual as follows:

There is a genetic cause (mutation) known that ‘changes’ the colour tone
expression of carotenoids in the plumage from red into yellow.
I’ve seen that mutation in many species, including Redpolls, and in my
opinion the crown colour of this particular bird is also caused by that
mutation. It is of course possible that the relevant gene for ‘yellow carotenoid’
is widely spread amongst certain Redpoll populations. Perhaps all the
yellow-crowned birds seen so far in the UK belong to the same
geographical population and are therefore more or less genetically
related to each other. I’ve seen several museum specimens with this
aberration which were collected more than 100 years ago all over Europe
so the gene is not uncommon in the species.

In his detailed online redpoll identification paper Worcestershire Redpolls and a Guide to their Separation, Andy Warr states:

First-winters and female Lesser, Mealy and Arctic Redpolls generally show a crimson cap, with varying degrees of brightness, though it is not uncommon for some to show orange, copper, yellow, even brownish caps, or any combination of the aforementioned. These colour variations are exceptionally present on adult male Lesser and Mealy, though is reported as common in captive bred birds, but more regularly encountered in adult male Arctic.

The paper includes a range of photos to illustrate the variation in cap colour.

So, mystery solved? Maybe … In the meantime here’s a photo of one with a not so obvious yellow crown taken at Aylesbury in neighbouring Buckinghamshire by Mike Wallen in March 2006. The worn, buffy tips to the outer greater coverts point to it being a first-winter. It was in a flock of about 50 in an urban area.

‘Goldpoll’: Lesser Redpoll with gold crown patch, Buckinghamshire, March 2006 (Mike Wallen)