Controversial age assessment of White-fronted Goose

Found by Dave Warner on 17th January, a White-fronted Goose was present with a mixed Greylag and Canada Goose flock at Sywell Country Park and remains there today. Initially aged as a first-winter, it has since sparked some controversy over how old it actually is.

Shortly after Dave had seen it, I found it still with the local geese, in a field on the north-east side of the reservoir and managed to grab a few photos through the park’s rather thick boundary hedge before it walked off over the rise of the field. It initially appeared rather plain-looking but was also sporting a noticeable white forehead.

First-winter White-fronted Goose, Sywell CP, 17th January 2022 (Mike Alibone)

Appearing to lack the black belly bars of a ‘standard’ adult – at least when viewed from its left – I was happy enough that it was indeed a first-winter, albeit with a fairly well-developed white blaze. When viewed from the front, however, it displayed some less conspicuous, thin dark lower belly bars and some on its right side, these normally being associated with more adult plumage.

First-winter White-fronted Goose, Sywell CP, 17th January 2022 (Mike Alibone)

Having tweeted an image out, Tom Lowe made the comment: Pale nail, white blaze, belly bars and squared flank feathers make it an adult, surely? That was based on the image above and it’s difficult to disagree but there are a number of conflicting ID criteria out there.

First-winter White-fronted Goose, Sywell CP, 17th January 2022 (Mike Alibone)

For example, Stoddart (2020) states: Adult Russian White-fronts have a small white ‘front’ (actually the forehead) and highly variable black belly barring. Juveniles and early first-winter birds (the white ‘front’ and black belly markings are acquired during the first winter) lack these features. The keyword here is early. This suggests that first-winters, later in the season, can have black belly bars.

Cramp & Simmons (BWP 1977) states: White forehead appears during first winter but black bars of underparts lacking or incomplete until second autumn. Again this suggests that some black bars may be present during the first winter. Relating specifically to first-winter (and first-summer) birds, it further states: Virtually no black feathers on belly but those of sides of body with contrasting edges like adult.

Relating to first-winters, Reeber (2015) states: Black ventral bars are absent or reduced to a few spots. And furthermore: Second winter identical to adult but adult type birds in autumn/winter lacking black ventral bars (black over less than 10%) could be in their second winter.

So it would seem, from the above references, that it is possible for some (minimal) black to be present on the bellies of some first-winters.

However, this does not explain other features on the Sywell bird being at odds with what is generally accepted as being consistent with first-winter birds.

Looking at the nail of the bill which, despite being illustrated as black by Cramp & Simmons, they state: Bill nail (of juvenile) dark horn becoming white during first winter. This conflicts with Reeber, who states, of juveniles, that the bill has a dark nail but subsequently goes on to say that the bill gains adult colours between mid-winter and spring.

The bill nail of the Sywell bird appears to be pale horn to whitish. Interestingly, Dave Irons’ photo ID gallery shows images of immature Whitefronts taken in November with a pale bill nail, and some in October with extensively dark nails. It is well known that blackish bill nails can remain well into the winter, too. Images of some November birds illustrate a white facial blaze to the same extent as the Sywell individual.

Apart from the extent of black on the underparts, extent of white facial blaze and bill pattern, the stage of moult also plays an important role in ageing.

According to Cramp & Simmons, adults post-breeding undergo a complete moult which is mostly finished before reaching winter quarters. Post juvenile moult, however, is partial. Some moult mantle, scapulars, chest, and longer flank feathers November – January and all body feathers are renewed by February. Also, first-winter/first-summer take on some adult-like feathers. Shape of moulted feathers of mantle and breast square but not as broad as adult. Sometimes medium coverts also moulted but usually many juvenile wing coverts are retained.

Reeber, too, makes similar comments regarding moult. In winter one should expect both adult-type birds and others with an obvious mixture of two generations of feathers among young birds. He goes on to say: until the second pre-basic moult (first summer), the wing feathers are juvenile, often obviously worn, as well as the retrices. And with regard to feather detail: (Adult) feathers of the mantle and scapulars are square-tipped, medium brown with white fringes and black subterminal bars.

Looking again at the first of the above images, it appears (to me, at least) that there is a contrast between what appears to be fresh, second-generation mantle/scapular feathers, with an adult-type pattern described above by Reeber, and the wing coverts, which appear to be faded and worn with abraded tips, indicating retention of first-generation juvenile feathers. The tail feathers also appear pointed and possibly worn, too.

If that’s the case, then the bird is what I would describe as an ‘advanced’ first-winter. If that’s not the case then, taking into account a statement from Reeber that second-winters are generally identical to adults but adult type birds in autumn/winter lacking black ventral bars (black over less than 10%) could be in their second winter, then the Sywell bird might be of that age.

Let’s face it, most birders scanning through a flock of Whitefronts would simply be appreciating the beauty of the flock or looking for other species which might be in the mix, cursorily differentiating between obvious adults and obvious juveniles. It’s only when a lone individual turns up with a local gaggle that it comes under scrutiny …

The first Pale-bellied Brent Goose for Northamptonshire

A great find by Jon Bowley at Boddington Reservoir this afternoon was the first confirmed Pale-bellied Brent Goose for Northamptonshire. Possibly associated with Storm Arwen, its arrival today coincided with that of a Common Scoter at the same locality. Interestingly, both birds remained close together while on the water this afternoon.

Adult Pale-bellied Brent Goose and first-winter female Common Scoter, Boddington Res, 27th November 2021 (Mike Alibone)

Pale-bellied Brent Goose is the race hrota, which breeds from the east Canadian Arctic to Svalbard and winters on both coasts of the north Atlantic. It would appear to be exceedingly rare inland and all previous occurrences of Brent Geese in Northants have related to the Dark-bellied race bernicla, which occurs in the county annually in very small numbers, normally as lone individuals joining flocks of Canada Geese for short periods of time during spring and autumn passage.

Adult Pale-bellied Brent Goose, Boddington Res, 27th November 2021 (Mike Alibone)

Identification is straightforward, Pale-bellied showing strong contrast between the sharply-demarcated black breast, pale belly and flanks, with the pale brown upperparts ‘sandwiched’ between black neck and the black feathers of the closed wing. Dark-bellied is much more uniformly coloured. The lack of whitish fringes to the upper wing coverts easily ages it as an adult.

Greenland White-fronted Goose at Summer Leys

Sometimes hunches pay off. After the incredibly short stay of the Greenland White-fronted Goose at Wicksteed Park, Kettering on 6th January, it seemed logical to assume it might emerge somewhere else in the county – if we were lucky.

On 16th January, a White-fronted Goose was reported with Greylags just outside the northern boundary of Summer Leys LNR and it was seen and reported again the following day. Despite it being a good winter for the species so far, under the current circumstances, a lone whitefront was surely worth some scrutiny and on the 18th a visit to check it out was duly made.

And there it was – in the water meadow by the Nene, just north of Wollaston Lock – the tell-tale orange bill, along with the characteristic dark plumage of the Greenland race flavirostris, easy to find among the 80 or so Greylags which it had latched on to.

Adult Greenland White-fronted Goose, near Summer Leys LNR, 18th January 2021 (Mike Alibone)

Closer scrutiny reveals the slightly thicker neck than the nominate albifrons race (‘Russian’ White-fronted Goose), although this is subjective and dependent on the bird’s stance. The slightly darker face is also evident as well as, from the rear, the thinner white terminal tailband than that of albifrons.

Adult Greenland White-fronted Goose, near Summer Leys LNR, 18th January 2021 (Mike Alibone)

Adult Greenland White-fronted Goose, near Summer Leys LNR, 18th January 2021 (Mike Alibone)

Adult Greenland White-fronted Goose, near Summer Leys LNR, 18th January 2021 (Mike Alibone)

The unique patterning of the black belly bars identifies this bird as the same individual which visited Wicksteed Park on 6th January. Interestingly, this bird had also been present at Watermead, near Aylesbury, Buckinghamshire (approximately 46 km south of Summer Leys) on 31st December 2020. This is the 6th record for Northamptonshire. It is still present today, 19th January.

Adult Greenland White-fronted Goose, Wicksteed Park, 6th January 2021 (left, Nick Parker) and near Summer Leys LNR, 18th January 2021 (Mike Alibone)

Greenland White-fronted Goose winters principally in Ireland and western Scotland. Small numbers winter in Wales and small groups can also be encountered in other parts of Scotland and north-west England. The global population of Greenland White-fronted Geese in spring 2020 comprised 21509 individuals, up very slightly on the 21466 (0.2%) on the previous year; 10418 were counted in Ireland and 11091 in Britain (Fox et al. 2020).

Variation in the Clifford Hill White-fronted Geese

It was only yesterday when I managed to catch up with the two adult white-fronts at Clifford Hill Gravel Pits (or, if you prefer the newbie name, Nene Washlands). These birds were first discovered on 5th December and they appear to have settled in with the local Greylags, which are normally in the vicinity of the eastern end of the Main Barrage Lake.

While they are clearly part of the UK influx of ‘Russian’ White-fronted Geese, which took place during late November, one of these two birds shows some interesting characteristics.

White-fronted Goose, Clifford Hill GP, 10th December 2020 (Mike Alibone)

Larger than the other, it has an unusually extensive white facial patch, which is very striking in the field. While these patches can vary in size, I have never seen one this extensive, nor can I find any images which match it in terms of its broadness – including a spike extending to the eye – or in its reach on to the crown. There is also a white area extending below the gape line to the sides of the chin as the images here show.

White-fronted Geese, Clifford Hill GP, 10th December 2020 (Mike Alibone)

The difference between the two birds is obvious when they are together and the bill of the larger bird is also longer, broader, shows a very pale basal area (further contributing to the impression of a large white face patch) and an orange wash, albeit restricted, on the proximal part of the culmen, while the tip is potentially ‘teat-shaped’.

White-fronted Geese, Clifford Hill GP, 10th December 2020 (Mike Alibone). Inset: Tule White-fronted Goose (Reeber, 2015)

According to Reeber (2015), many of the above features are characteristics shown by the race elgasi, Tule White-fronted Goose which, breeding only in Alaska and wintering in California, is the rarest and has the most restricted range of all races of White-fronted Goose.

However close (or not) the resemblance appears, though, there is a good deal lacking. Elgasi is large, longer legged, longer necked, longer billed and generally much darker than ‘Russian’ White-fronted Goose. In general, male white-fronts are larger and slightly longer billed than females, which explains the size difference between the two Clifford Hill birds. However, there is still the extensive white facial patch, the bill shape and colour which add interest to this bird and make it stand out. Is this bird simply at one end of a range of variation or are there some Tule genes in there, somewhere? Alaska is not far from Siberia as the goose flies …

The Stanwick ‘Ferruginous’ Duck

It’s not called ‘Fudge Duck’ for nothing. Closely resembling the real thing, hybrids abound, enticing observers into a ticking temptation trap, in which nothing is quite what it seems …

When the news broke of Ferruginous Duck or hybrid at Stanwick GP, at around midday yesterday, it was clearly a sensible move to throw in that cautionary caveat – the dreaded ‘h’ word – as rare ducks are notorious for carrying rogue genes. Although looking good at first sight, this was one such bird which, upon closer scrutiny, clearly did not pass muster. OK, it could be said it was mainly but unfortunately, not wholly, Ferruginous. The following assessment is based upon published images of the bird and follows the most up-to-date ‘hybrid checklist’ of features given by Reeber (2015).

It is assumed the bird is an adult female on account of the iris being dark brown (paler in juvenile/first-winter). In terms of size, it’s too large for a Ferruginous Duck. Two of the images below suggest it is virtually the same size as a Pochard. It also appears too bulky. Ferruginous Duck is small and any bird close in size to, or larger than, Tufted Duck is likely to be a hybrid.

Female Ferruginous Duck-type hybrid, Stanwick GP, 25th January 2020 (Adrian Borley)

Female Ferruginous Duck-type hybrid, Stanwick GP, 25th January 2020 (Adrian Borley)

Head shape is not perfect for Ferruginous Duck and is similar to Pochard. On close inspection, the head shows two slightly paler brown patches, one at the bill base and one on the rear cheeks, which is strongly indicative of hybridisation with Common Pochard. The bill colouration also indicates a hybrid as the pale subterminal mark extends along the sides of the bill, which would form a ‘U’ shape when seen from above. The subterminal mark should not extend in this way (although many published images of so-called ‘pure’ Ferruginous Ducks show it – including some of Reeber’s – so its validity may be questionable). There also appears to be fine traces of black at the bill base – another hybrid characteristic.

Female Ferruginous Duck-type hybrid, Stanwick GP, 25th January 2020 (Steve Fisher)

Female Ferruginous Duck-type hybrid, Stanwick GP, 25th January 2020 (Steve Fisher)

Female Ferruginous Duck-type hybrid, Stanwick GP, 25th January 2020 (Adrian Borley)

The belly is not sharply demarcated as it should be for an adult and it appears a little smudgy. Also, there appears to be a slight demarcation between the breast and the flanks, which is not right for Ferruginous Duck.

Female Ferruginous Duck-type hybrid, Stanwick GP, 25th January 2020 (Steve Fisher)

All the above features exhibited by this bird indicate a hybrid origin. Reeber suggests that hybrids are relatively frequent in the wild and even goes as far as stating that in Western Europe, hybrid-like Ferruginous Ducks are commoner than pure individuals!

An exciting new addition to the Northamptonshire List

Completing the latest duck race, Falcated Duck makes it over the line … after a third of a century.

It has only taken 33 years but the drake Falcated Duck, which first arrived with Wigeon at Welney in Norfolk in December 1986, before relocating to Pitsford Res in February 1987, has just been accepted by the British Onithologists’ Union as the latest addition to the British List.Found by Dave Burges and Matthew Rodgers on 15th February 1987, it remained at Pitsford until 5th April and the record was duly submitted to, and accepted by, the British Birds Rarities Committee. It reappeared the following winter, when it turned up at Thrapston GP on 12th December, remaining there until 24th, before relocating to nearby Ringstead GP, from where it commuted to and from Thrapston between 16th January and 6th March.

Falcated Duck, Martin Mere, September 2014 (Francis C Franklin/Wikimedia Commons). Captive for illustration only.

Prior to the return to Northants it was present again at Welney during the autumn. An image of the bird appeared in British Birds 80: 255.

Falcated Duck breeds in eastern Siberia and has wandered to Pacific coast USA, south-west Asia, the Middle East and Europe, where occurrences have often been dismissed as escapes. Its population is currently thought to be 78,000-89,000 individuals.

Velvet Scoters in focus

Found on 27th October, a small flock of Velvet Scoters on Thrapston’s Town Lake is the first in the county since 1995 and rightly continues to attract a steady stream of admirers. Widely touted as ‘juveniles’, additional high-quality photos to emerge allow a more analytical approach to ageing, sexing and individual recognition.

The original eight, found on 27th October, had become six by the following day when two distinct individuals, which frequently kept apart from the rest of the flock, had departed. As well as being the largest flock to be recorded in Northamptonshire, the remaining six may also be in line to break the long stay record for more than one bird, having been present now for at least eleven days. The record is currently held by two which were mobile between Hollowell and Ravensthorpe Reservoirs, from 7th to 27th November 1983.

First-winter Velvet Scoters, Thrapston GP, 29th October 2018 (Bob Bullock)

Close examination of the excellent images obtained by Alan Boddington and Bob Bullock enables individuals to be readily identified by their head patterns, which are quite variable. Because of the broad, pale feather fringing on the wing coverts, the ‘long staying six’ (A to F) can be aged as first-winters and at least two of these (B, D) are young males, the dull yellow areas being visible on their bills. None of the other four shows the slightest hint of yellow but C, E and F are showing pale horn-coloured areas on, or around the sides of the nail. This is interesting because, according to Reeber (Wildfowl of Europe, Asia and North America, 1995), this is a characteristic associated with adult females and not present in first-winters.

Adult female Velvet Scoters, Thrapston GP, 29th October 2018 (Bob Bullock)

The ‘short staying two’ (G, H) are adult females with uniform dark plumage, which includes, most importantly, the belly – visible in the only flight shot (below) obtained so far. First-winters have a pale belly until adult plumage is acquired later in the winter or during their second calendar year. Hopefully, the remaining birds will continue their stay at Thrapston for some time to come.

Adult female Velvet Scoters, Thrapston GP, 29th October 2018 (Bob Bullock), birds ‘G’ (left) and ‘H’.

First-winter Velvet Scoters, Thrapston GP, 31st October 2018 (Alan Boddington). Birds ‘C’ (left) and ‘D’.

First-winter Velvet Scoters, Thrapston GP, 31st October 2018 (Alan Boddington). From left: birds ‘A’, ‘D’ and ‘B’.

First-winter male Velvet Scoter, Thrapston GP, 31st October 2018 (Alan Boddington), bird ‘D’.

Ageing process of the Stanwick Pink-footed Goose

Since it was first discovered, the Pink-footed Goose, which has been present with the resident Greylag flock at Stanwick Gravel Pits throughout the winter, has undergone a considerable change in appearance.

Juvenile Pink-footed Goose, Stanwick GP, 12th October 2017 (Steve Fisher)

It arrived as an obvious ‘fresh’ juvenile in October last year. Its overall appearance was scruffy, dull and almost uniform brownish, rather dark-headed and only narrow, dull pale fringes to the scapulars, coverts and tertials. Its bill was also dark, with a dull pink band behind the nail and extending faintly along the cutting edge of the upper mandible. Thanks to images captured by Steve Fisher and Angus Molyneux, it’s easy to see the progression from juvenile to adult-type plumage which has taken place over a matter of almost four months.

Pink-footed Goose, Stanwick GP, 10th January 2018 (Steve Fisher)

By January it had acquired adult-type plumage, with streaked rear flanks, a contrast between upperparts and underparts, broader, whiter fringes to mantle, scapulars and coverts and a brighter pink bill (although lighting may exaggerate differences in photos).

Pink-footed Goose, Stanwick GP, 5th March 2018 (Angus Molyneux)

By March, the bird looks neat and has developed some whitish feathering around the base of the bill, which is found quite commonly in adults.

Clifford Hill Bufflehead goes west

Turning up and performing well in front of the hide at the southern end of Daventry Country Park yesterday, ‘Buffy’ was finally stripped of her celebrity status as she revealed more of that tell-tale ring detail.

Female Bufflehead, Daventry CP, 27th June 2017 (Bob Bullock). An escape from captivity with a non-conformist metal ring on the right leg.

Thanks to some excellent images from Bob Bullock, it became apparent that our Bufflehead’s ring format does not conform to any which is used in either Canada or the USA – either now or in recent history. Digits around the centre of the ring include random numbers 38, 58, 60 (or 09) and there is no alphanumeric contact detail in smaller text above or below these numbers.

Female Bufflehead, Daventry CP, 27th June 2017 (Bob Bullock). An escape from captivity with a non-conformist metal ring on the right leg showing number 58.

Female Bufflehead, Daventry CP, 27th June 2017 (Bob Bullock). An escape from captivity with a non-conformist metal ring on the right leg showing numbers 38 and possibly 09.

Female Bufflehead, Daventry CP, 27th June 2017 (Bob Bullock). An escape from captivity with a non-conformist metal ring on the right leg.

I am grateful to Chris Wood of the Cornell Lab of Ornithology, Ithaca, New York who, upon receiving copies of the above images, kindly commented as follows: “Honestly, I can’t imagine this ever being used by a researcher here. Bands have been standardized for a long time now and this just doesn’t look like anything we would use.”

Danny Bystrak, Wildlife Biologist at the Bird Banding Lab, Patuxent Wildlife Research Centre near Washington, USA, also commented: “The band looks narrow and over-sized is not something I have ever heard of anyone using in the US or Canada.” [via Chris Wood]

So, there we are. Our Bufflehead has indeed gone west … along with any chance of it being a new bird for the county.

Postscript: it is reportedly back at Clifford Hill GP today.