Bean Geese (7) - there they are, finally

Yesterday, Lützen Portengen found minimal 35 Taiga Beans in a flock of Tundra Beans near Udenhout, Brabant. This afternoon, I observed the group for more than two hours. Here some pics on which I will comment later.

Warning: these pictures also include several Tundra's, two orange-billed 1w Greater Whitefronted and other stuff! Have a look...

Two juvenile albifrons with orange bills. Are they F1 hybrids of a pair of rossicus x albifrons? I couldn't find their parents.

All Taiga Bean fabalis foraging in line, as they did the whole time at the edge of the big flock of rossicus.

Mix of rossicus and fabalis. 12 of the latter. Note the more slender structure and bowed necks of the birds from the Taiga!

Another part of the line of fabalis also mixed with most rossicus. The Taiga birds didn't move a lot.

Some just landed albifrons and rossicus in front of the massive group.

Some rossicus with two orange bills. Don't think it are fabalis. I followed these birds after landing and concluded that it were two males with type B bills!

Neckband from Germany.

Two fabalis, just one visible at left.

Alert at the background! Part of the line.

Alert male with a type A bill. Some more fabalis around, but not visible.

Interestingly, the little yellow-billed bird at the left was paired with a straight fabalis. That must be a female! The birds in the centre are more straight forward.

rossicus: 1w, ad male type B, ad, ad, ad

The same group.

Can you do it by yourself?

Bean geese (6) - an interesting pair on Shetland

Again some very interesting pictures of Shetland. Roger Riddington commented on these by e-mail:

On 1st February, a message went out on our grapevine about two Taiga Bean Geese, and that evening some pictures appeared on one of the Shetland birding blogs (http://www.shetlandbirding.blogspot.com/). See entry for 1st Feb (best to ignore some of the comments in the text).

I was intrigued by the pictures on the web since they seemed to show a rather skinny-billed bird that looked similar to the adult female Taiga in the group we corresponded about in December – whereas the other bird looked to have a bill structure more like Tundra. Anyway, a couple of days later I managed to get out of the office for a couple of hours and went to see them. In real life I was struck by two things – 1) that overall, in terms of overall size, body shape and structure etc, the two birds were pretty similar. I could see why people thought they were both the same form (and some people are of the view that they are both Tundras!). But through a telescope, the bill structure looked quite different, to me. The orange-billed bird has a much more slender bill, with a more or less entirely straight cutting edge to the upper mandible, a very slim, flat lower mandible, and I would say a bill depth at the base which is slightly but distinctly smaller than the second bird. The stripy-billed bird has a bill that is about the same length, but is deeper at the base, with a much deeper base to the lower mandible, and a very distinct curvature to the cutting edge of the upper mandible.

Based purely on bill structure, I felt that the ‘best fit’ solution was a petite female Taiga and a big male Tundra. But I can see that when you have two vagrant birds like this it is more often going to be the case that they are the same form. The similarities in overall shape and size was also confusing. I would hesitate to say that the two were ‘paired’ but they were certainly together the whole time I watched them – if anything, the stripy-billed one was slightly larger/heavier and perhaps spent a little more time alert – reinforcing my tentative view that it might be a male.

The light wasn’t great, so my pictures are again a bit grainy and distant – but if you felt able to comment I would be interested in your opinion.

All the best,

Roger

This is one of the bills you wouldn't expect on such a body! 

Hi Roger,

Thanks again for sending me these pictures. Your description is quite complete. The only thing I would say: yes, this is a pair of fabalis and the male has a type D bill. 10% of fabalis has this colouration.
It would be strange to seperate the birds into two species, since their is no known record of an hybrid pair of fabalis and rossicus (Heinicke in litt) and they behaved as a pair.

Except the bill, everything on this bird points to a classical, rather big Taiga Bean. Still, the variability of the billstructure in both rossicus and fabalis isn't described and depicted properly in the literature.
Thick lower mandibles like this male has, are very rare in fabalis. Pro fabalis is the concave culmen and the overlapping tip of the upper mandible. But such an deep and bowed base of the lower is
surprising. Note that the orange bills always look a bit more slender as the result of a kind of visual effect.

These pictures do stress my vision to have a databank once, with hundreds of heads 'en profile' of both species to depict their variability. For example, have a look at those pure fabalis flocks: http://www.birdphotos.dk/index.php?view=category&catid=910&page=3&catpage=1&option=com_joomgallery&Itemid=3&lang=en
Thanks, best regards,

Albert
 

Bean Geese (5) - new status and recent developments of the species in The Netherlands

Taiga Bean Goose fabalis - turned out to be rare since 1987

Tundra Bean Geese rossicus - the most common of Beans in The Netherlands

This link leads to the paper which is to be published in the next number of Limosa.

We hope to have cleared it somewhat....

Bean Geese (4) - Misleading pictures...

Yesterday, a Taiga Bean Goose was reported right in an area where Taiga's winter sometimes. The pictures are showing an alert, quite yellow and slenderbilled Bean. The base of the upper mandible is not so high and the lower mandible looks straight from the base to the tip. Also, the slender and rather long neck looks good for fabalis, as the deep brownish colouration of the head, slightly converging into the greyish neck. So far, reasons enough to visit this bird.

This morning, the bird was still present and found by PieterGeert Gelderblom. We observed the bird for some minutes, carefully judging the billshape. In the field, the height of the grinning patch (or curve of the lower mandible) turned out to be better for rossicus. Although the base of the upper mandible wasn't high, the bill looked to stubbish for a fabalis due to the length. The colouration of the head didn't differ from the other 9 birds. The size of the bird did fit a big rossicus or small fabalis, but the structure didn't differ from the others. The group contained typical rossicus birds with type C and D bills. Did we forget the rule: Bean Geese could be best identified by group? I think we were hoping for just one fabalis in this very mild winter.

Or can pictures be so misleading?

Rossicus - 7/1/2012 - Vlijmen (sorry for the bad quality)

Bean Geese (3) - more from Shetland

Hugh Harrop sent me some new pictures from the Bean geese from Shetland. He noted: ‘ They are clearly very interesting birds and I continue to scratch my head! The bills are clearly interesting!’
 

Yes, they are, I immediately thought. In previous decades, identifying Beans was all about bills. Yellowbilled, huge Bean geese were fabalis, and short-blackbilled were rossicus. It is logic to focus on their bills, because there are no obvious other characteristics of Beans that differ in such way. Say ‘character’ and’ Bean’, you have to use the word ‘slightly’, because every difference between rossicus and fabalis is slight: bill, size and structure.
But now only about the bills. According to Roselaar (1977), one of the few morphological studies about the Bean geese complex, the structure of the bill is important, but difficult to measure.




Taiga Beans (fabalis) do have a long and thin upper mandible, which sides are parallel, the nail is round (looking right from above), lower mandible is straight and thin. 
Tundra Beans (rossicus) do have a shorter and higherbased upper mandible. The sides are converging towards the tip. The nail is more oval and the lower mandible thicker and strongly curved.
That bill structure is more important than bill length, shows table 1. Bill length does only differ some millimeters between rossicus and fabalis. On average, the bill of a fabalis is slightly longer. The only significant difference in billmeasurements Ruokonen et al (2008) found, was the height of the grinning patch: rossicus 7.29 (n=10) and fabalis 5.8 (n=17). Also slightly!
What are we talking about?! I hope clear it up a bit with these pictures:

1a Rossicus - Thick lower mandibles like these are quite common in flocks in the Netherlands. Interestingly, they show up more in the late winter. Are they from more eastern parts of the Rossicus area? 20/1/2011 in NL - Max Berlijn

1b. Rossicus. Bills like these are the most common: a curved lower mandible, less orange than black. - Albert de Jong

1c. Rossicus - With thick lower mandible - 2/1/2012 - Albert de Jong

2. Rossicus - Male, shot in 1854 (specimen) in NL - Fred Visscher

3. Fabalis - female, 25/2/1871 in NL - Fred Visscher

4. Fabalis - Note the thin lower mandibles. The bill length of the bird on the right isn't very long.  February 2011 in NL - Albert de Jong

 Have a look at these birds now. What about their bills?

Shetland 1

Shetland 2

Shetland 3

Shetland 4

Or what about this stranger on 8th January 2011 in The Wieringermeer, The Netherlands ? We discussed this bird on Dutch Birding. The positive ID as a female fabalis was confirmed by expert Thomas Heinicke as you can read. Looking only at the bill, we can see the lower mandible isn't curved downwards, but straight and thin. Towards the tip, the upper mandible overlaps the lower a bit, which is seen regularly in fabalis. See also 'Shetland 1' above, that shows two slender-billed birds like the bird here below. Shetland 3 also shows such a bill. Shetland 2 has a shorter bill than you possibly expect in fabalis and more in rossicus, but as table 1 shows, length doesn't matter that much. Amongst the biggest Dutch flock of up to 70 birds of last winter, described here, there were some (females I think) with bills like this. The structure of this bill is typical for fabalis. So far, the focus on one aspect of the whole picture you need to ID Beans. Hugh also noted that the size of the Shetland birds is 'to be slightly smaller than the (small) Icelandic Greylags we have here and not much bigger than the 'biggest' Tundra Beans in the same flock.' I think that is a good description for fabalis, since the more delicate structure and size of fabalis is somewhere between the more bulcky Greylags and Tundra´s. Structure does matter may be more than size! But is also more difficult to describe. The future job is to get the right picture(s) of the variability in fabalis and rossicus. I think there has been a lot of improvement in the last years.....

Fabalis (female) between Rossicus - Wieringermeer, Netherlands - 8/1/2011 - Fred Visscher

More bills at: Finnish fabalis

Danish website with a lot of fabalis

More Finnish pictures

 Another nice source from Finland

Swedish mixed pictures  

 Nice collection from Finland / breeding birds

A lot of rossicus

Bean Geese (2) - some from Shetland

These pictures were sent by Roger Riddington from the UK. They were made between November 29th and December the 4th on Bigton, Shetland. Grabbed from a flock of up to 20 birds.

What should it be? Rossicus or fabalis? I got reactions from some Dutch birders. Experienced Bean geese-watchers PieterGeert Gelderblom and Lützen Portengen answered with: 100% fabalis. Also did Arnoud B. van den Berg. Others have doubts. In my opinion, it are Taiga Beans obviously. I have added some comments below the pictures.

Taiga Bean Goose - Note the slender shape of the birds. Though it is hard to judge their size beacause there is no other species in this picture, I focus on shape, head profile and bill. I see high, pronounced breasts, more typical for Taiga due to their long necks. Also note the head profile: the forehead is flat and converging into a rather concave culmen. The lower mandibles are flat and I can hardly see any grimace in the beaks. The bills are quite long and rather orange. From left to rigt: type C, D, B and A.

Pair of Taiga Beans. Note the low base of the upper mandible, which forms the more 'duck-like' bill.

Some Tundra Beans can show such a yellow bill. The flat lower mandible is a good feature of Taiga Bean.

Type B or C (cf Burgers et al 1991). This type of bill is quite common. Note the concave upper mandible.

Based on the unmoulted coverts and the bill colouration, this must be a couple of juveniles. Young birds can be seperated from adults by their bills, which aren't fully grown and have a more vague colouration.

A family of two juveniles and an adult (in front). Note the pronounced breasts/necks an the typical crinckle in the slender neck of the adult. The jizz of this bird is very distinct for Taiga.

Not the clear cut. Pictures like this one can cause a lot of dicussion. The relationships between these birds are unclear. What is their size, relationship et cetera et cetera? Judging the height of the 'grinning patch' or grimace in their bills, this must be Taiga Beans. Ruokonen et al (2008) found that one of the best indications for Taiga.

Taiga Bean Geese (1) – a different approach

I received some pictures of Bean geese from the UK in the past weeks. This autumn, Taiga Beans have been reported from other places than the regular two: Norfolk and the Slamman Plateau. In The Netherlands, only this individual has been reported this autumn.

Taiga Bean Goose / Anser fabalis fabalis - 22-2-2011 - Wassenaar (NL)

For some years now, Taiga Beans do have my special interest. The identification of this species is very difficult, since the variation in both Tundra and Taiga Bean is far from clear. The Bean Geese complex has a very complicate taxanomical history. Recent MtDNA-studies by Ruokonen et al (2008, 2011) have shown that the Bean geese should be treated best as one species fabalis with the subspecies fabalis and rossicus, in stead of fabalis and rossicus as separate species. The latter was decided firstly by Sangster and Oreel (1996), based on Burgers et al (1991), but isn’t followed by all the taxonomists. Subspecies or species, to separate the two in the field is still a hard job for most birders. In the past decades, thousands of Taiga Beans were counted in The Netherlands by Leo van den Bergh and other geese specialists. Somebody told me Leo drove into Hungary and other eastern European countries to follow ringed Beans!  I have never met him and only have read his publications. He described geese in terms of ‘black bills’,  ‘eastern tundrabirds’, ‘yellow bills’, ‘johanseni geese’ et cetera. Tens of the extremely eastern middendorffi he reported. But no pictures of all those birds were made. No blame to Van den Bergh: someone had to face that difficult geese! For decades his opinion influenced the picture of the Bean geese in The Netherlands. Still, geese counters fill in ‘black billed Taiga Beans’ on their forms.

I think that the identification of Bean Geese is troubled partly by birders themselves. Why? … Since birders use the wrong approach while watching Bean Geese. I mean, searching for that individual which has a bigger, yellow bill among all that typical Tundra Beans. 100% you will get one in a flock of more than hundred, because bill colouration is highly variable in Tundra Bean Geese (cf. Burgers et al 1991).

The different approach was firstly described by Huyskens (1986): ‘Bean Geese have a group-identity’, he cited his friend Paul Maes. Groups of big, slender, predominantly yellow billed Beans will be Taiga Beans. And just that groups have become rare in The Netherlands since the ’80. So, when you observe Bean Geese: take your time. Observe the group carefully. Search for families, pairs and juveniles. Try to get a good look of the size and structure of the birds. Also examine their behaviour. In The Netherlands, Taiga Beans are very alert compaired to Tundra Beans. They prefer huge grasslands with some open water nearby. Tundra Beans prefer crop fields. If you think you have some good stuff, check:

• It are big, slender geese, in size approaching Greylag Geese. They are foraging quietly and often laying down while eating.
• The average of yellow in all the bills (on average more than 50% yellow in the bills): Taiga.  
•  The head profile is flat and Pochard-like. (Note that the profile depends on the activity of the goose.) It is a combination of a concave culmen, low base of the upper mandible, a straight and thin lower mandible, sometimes bowed a bit downwards towards the tip. The lower mandible isn’t bowed strongly, so the beak lacks the ‘typical grinning patch’ of a Tundra Bean.
• The slender necks have in some postures a crinckle at the base, which creates a kind of a swanlike impression.  

Last  November, James Lidster sent me this picture of an individual in the UK. So, what groupwise approach? Well, let's see if we can note something:

This must be a Taiga Bean, since Tundra never shows a bill lenght that is the same as the head. The structure and size is also better for Taiga, probably a female.

Here is the figure of Burgers et al (1991) wherein you can see the variability of the bill patterns.

February 2011, The Netherlands: compare the bills and head profile. The bill type is between B and C.

Next week, some more pics of some families...