Definitely Eastern but which species?
This Bean Goose, a major Rarity in North American, has been present since around 10th November at Salton Sea, California. Julian Hough sent me a bunch of photos which proved irresistible…
The perplexing question is whether it is a more northerly breeding – Eastern Tundra Bean Goose ssp. serrirostris, or an Eastern Taiga Bean Goose, better known as Middendorff’s Goose ‘middendorffii‘ the latter being given full species status by some.
Great pictures, lots of information, but which is it?
Alsot have a look at this, highlighted by Paul leader in Surfbird forums: http://www.hkbws.org.hk/BBS/redirect…tpost#lastpost
It seems to show the serendipitous comparison of 2 middendorffii and 2 serrirostris in one flock- amazingly the first records of Bean Goose for Hong Kong.
The following amazing set of photos taken by Ken Kurland (1st set) and Larry Sansone (2nd set). Thanks guys, makes ID challenge mush easier to at least attempt. Great job!
Tricky Middendorff’s type Bean Goose with Pacific White-fronted Goose, ssp. frontalis. Just to take a break from Bean Goose talk. I would love to find one of these Pacific White-fronts in Britain. I have seen them in N America. First views of a small flock, I thought they were White-front X Greylag hybrids or something – so big and unrefined looking were they!
All photo above of apparent Middendorff’s type Bean Goose (with Pacific White-fronted Goose), Salton sea, California. Ken Kurland. 16th November 2010.
Please excuse a Brit commenting on a North American rarity! Julian Hough sent me some wonderful photos of the Californian Bean Goose by Ken Kurland and Larry Sansone which ‘drew me in’. I have found it to be a bit of a conundrum but have probably learnt more about the Eastern Bean Goose taxa than previous sorties into the subject. As well as my own ruminations I learnt much by chatting with Richard Millington, Dan Brown, Tristan Reid and Chris Batty who all have ‘previous’ with Bean Geese.
My personal summary of the identification issues:
While Middendorff’s Goose was quickly heralded for this bird, my search image was of birds with an exaggerated long bill and swan-like (or even Swan Gooose-like) head and neck profile. That’s the kind we would like to see and are looking for in the UK- and some of us are still disquieted by several birds in Shetland and Falkirk last winter which might have been middendorffii.
The Salton Sea bird did not seem to me to have that kind of long, exaggerated head/ bill profile, and my first reaction was to wonder about eastern Tundra- serrirostris. Following research and helpful discussion this is what I currently think about Salton Sea bird.
- It’s a least 2nd Cal year or older. Most of the upperpart and flight feathers are new, fresh adult types. I see old (unmoulted) feathers in the small wing coverts and in the body plumage. They don’t look like juvenile feathers, but old versions of the new feathers. Our juvenile/1st winter grey geese usually have lots of obvious slimmer more U shaped buffy fringed feathers over the upperparts at this time of year. Pyle seems to indicate some retained unmoulted feathers are normal in these areas for adult White-fronted Goose in November – guess it’s OK for adult Beans to still have the same.
- It’s a big Bean Goose. In body bulk it’s larger than accompanying frontalis White-fronted Geese. This is especially obvious in the flight photos. These Pacific White-fronts are larger than the Russian White-fronts (ssp. albifrons) which winter in Britain.
- The bill at first glance doesn’t look that long- perhaps an impression affected by the very deep bill base and also by precise angle from photographer/ posture of bird etc. As others have said though in relation to head it generally appears about same length as head or just shy of it. Long-billed compared to shots of rossicus and serrirostris.
- The bill is slightly concave in profile especially just above the orange patch, where it becomes quite narrow. Tundra Bean tends to remain straight or convex and lumpy without fineness near the bill tip.
- The head colour intrigues me as in varying lights I still comes out as being rather pale, lacking the cold dark brown tones and the strong contrast with the lower neck of Bean Geese seen in Britain. On most Beans- when light factors are accounted for- the head and upper neck are dark coldish brown, contrasting obviously with paler lower neck and breast. Hypothetically this may be a good pro-Middendorff’s feature to be tested.
- The contour of the bill and forehead is actually a continuous straight line right up above the eye. So even though the bill is thick-looking, there is actually a smooth rather Swan-like profile to the head and bill. Tundra Bean seemingly including serrirostris, have an obviously marked ‘forehead’; a more vertical rise at the bill base produces a lumpier, squarer head shape. The combination of the more Swan-like profile on a (warmer) paler head lacking contrast with neck seems ‘Middendorffish’!
- The auxiliaries do appear to be genuinely darker than the slightly paler underwing coverts. A feature previously mentioned in print by Dan Brown as hypothetically useful for separating Middendorff’s. Worth remembering and following up.
So overall its bill length and profile, head and bill profile, head colour, body size and possibly auxiliaries favour Middendorff’s. However it’s not an easy or classic bird- at least as I understand and am a little uneasy to say it robustly a straightforward Middendorff’s- at least without further information. These are my outstanding issues:
Question about ID as Middendorff’s
- Neck length not entirely convincing. In such a major rarity one would hope for a ‘classic’ individual with long ropey Swan-like neck. In all the shots on the ground it doesn’t look particularly long-necked- perhaps one of Larry’s shot being an exception. However the same is repeated in flight where one would think a longer neck would really show up. See flight shots alone and with Pacific White-fronts. It looks decidedly unimpressive in the neck department for the perceived impression of how Middendorff’s should look- doesn’t it?.
- I still wish the bill looked longer and thinner overall, especially at the ‘tip’ end.
Interestingly the auxiliary ‘fan’ does appear to be genuinely slightly darker than the underwing coverts. A useful feature for identifying Middendorff’s Goose?
All photo above of apparent Middendorff’s type Bean Goose (with Pacific White-fronted Geese), Salton sea, California. Larry Sansone. 17th November 2010.
Thoughtful comments from Dan, Tristan and Richard, based on the photos here. Thanks guys!
From Dan Brown:
Thanks for these – interesting bird. I always love a good ID challenge.
Well I agree with you in that it is certainly not a stonking great Middendorff’s, however I would not put it in the serrirostris/rossicus camp. The reasons for this are:
- the bird is clearly very large and robust
- The neck is relatively long but not as proportionally thickset as I would expect from a serri/ross.
- The bill although not a stonker is still pretty long
On this basis I would put it in the fabalis/middendorffii group. Obviously Middendorff’s is significantly more likely to occur in western USA than fabalis Taiga. Features which favour Middendorff’s are:
- The bill is still a reasonable size and more important robust with a deep base and a slightly concave culmen
- The cutting edge is heavily curved with a comparatively deep lower mandible though definitely not as deep as on some Middendorff’s (see below)
- There is a distinct lack of dark feathering around the bill base, typical on most fabalis unless they show white-front like pale feathering
- The general plumage tones of the head and neck in particular are warm almost cinnamony, fabalis is normally a colder tone.
- The axillaries appear dark and contrasting with the rest of the underwing colouration – this is something that may be useful in Middendorff’s ID but I’m not 100% sure on this yet.
- In flight the head appears deep chinned and almost hangs, far more so than on a typical fabalis.
In conclusion I reckon that this is a Middendorff’s but on a cautious note though it may be foolish to right off what used to be known as johanseni. There is still plenty to be done on these eastern Beans and a few key winter trips and some nice shots would certainly be informative to all. There is clearly a lot of variation between birds and I suspect between different wintering areas although one thing that does seem consistent is the bill patterning among these eastern Bean Geese – interesting?
Some of these may be of use/interest but you are assuming that ID’s are correct:
A similar bird to the US one in terms of bill structure:
Oriental Bird Club photo catalogue – scroll through for various images – I do NOT think that these are all correctly ID’d but it gives a useful indication of variation and complexity of ID’d birds correctly!
Another Middendorff’s but a similarly lighter-billed bird like the US one:
I suspect that if a Middendorff’s turned up in the UK that if it were with Taiga Beans it would stand out pretty well however the chances are quite high that it might arrive alone and therefore make direct comparison difficult.
Hope this helps a bit at least.
From Tristan Reid
Thanks for the images; what a beast (the frontalis Whitefront looks a stonker too)!
Firstly from a personal point of view the phrase ‘deep water and cannot swim’ would summarise how I feel about commenting on this bird 😉
However, that won’t stop me giving it a go!
As you suggest, this is a very large bird (certainly out sizing the frontalis White-fronted Goose that it is accompanying). To my eye the bill does appear very long (though I accept that some middendorffii can look longer). I cannot see this fitting into serrirostris particularly neatly; the structure of the bill seems wrong for this form. The bill seems to show the neater triangular shape (lacking the obvious bulbous/swollen base to the lower mandible that is shown in the Tundra group).
My feeling is that this bird is most likely a middendorffii; though I am not sure how confident I would be in ruling out fabalis/johanseni!
These links may be of use:
(Tristan also though he could see differences in the sonograms between rossicus and fabalis such that further study into calls of other Bean Goose taxa may produce useful differences.)
From Richard Millington
Leaving aside the issue of intergradation/hybridisation, the task seems to be to identify this adult vagrant as either a (long-billed) serrirostris or a (‘less-than-extreme’) middendorffii…
In some of the latest photos, the bird in question does look thick-necked (thus relaxed, unlike the frontalis behind in one image, which is stretch-necked). Given that frontalis is larger and bigger-billed than our albifrons, the Bean is still a big bird by anyone’s standards, and might it be able to stretch its neck longer?
It does not look quite as huge, nor as ‘swan-necked’ as classic middendorffii, and obviously it could be said to look too short-necked in flight.
So is it serrirostris? Serrirostris has a longer, deeper bill than the rossicus we are used to seeing in Europe, and it is a bigger bird overall. Not all serrirostris have short fat bills; some may have longer bills.
Averaging the overall length of the bill of the USA bird (I know it varies depending on the proximal point of measurement) it ‘approximates’ to about the same length as the head (skull).
This is arguably too long for serrirostris (which seems to average only 3/4 the head length: ‘folded back’, serrirostris bill reaches to midway between the eye and nape, not all the way to the nape).
Okay, a decidedly dodgy rule of thumb, but it at least shows that this bird really does have a genuinely long bill…
Also, the culmen is straight like a Taiga, with little of the ‘bump and dish’ effect seen on Tundra birds.
Also, the line where the loral feathering meets the base of the upper mandible seems to cut forward above the gape before sweeping up and arcing back to where the culmen juts in close to the top of the eye. On the USA bird the culmen ridge juts deep and high into the pre-orbital area. Again, a very subjective thing, but from photos it seems that on serrirostris this feather/bill join is more upright, less of an arc and does not sweep back into the head so much at the top.
Also, I think the cutting edge of the upper mandible (upper edge of the grin patch) looks straight for most of its length, suddenly curving down near to the face (about midway between level with the nostril and the gape); this looks more like the bill structure of Taiga birds. On Tundra forms, a more pronounced curve of this cutting edge looks more evenly bowed along the length of the bill, with the main ‘bend’ of the curvature falling about level with below the nostril (i.e. midway along the bill rather than towards the rear).
The head looks quite long and square, and less ‘puffy’ or rounded than on many serrirostris, and flat-chinned (Tundras often show a ‘dropped jowel’ effect to the chin line)
My personal, vague, and rather Heath-Robinson assessment the shape and size of the bill, and the bill/head profile (from various photos, I must stress) steers me away from Tundra (serrirostris) but towards Taiga (middendorffii) Bean Goose.
However, it does look too short in the neck, especially in flight. Perhaps, after all, it is a hybrid…?
I freely admit that I may be wrong (I often am), if that helps