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....

Counting waterfowl in NP Biesbosch

Counting waterfowl on a sunny winter morning is great. This morning I joined Theo and Jaques on the boat in the Sliedrechtse Biesbosch.

One of the first species we noted is the Bewick's or Tundra Swan. Some birds are still grazing on the wet fields, while most of the others have left to forage outside the NP. Some birds fled over nicely.

We counted up to 42 Blue Herons, a normal number due to the mild winter.

It is always nice trying to approach Gadwalls, a breeding species in small numbers and wintering in huge numbers in the area.

Hé, who is that? That must be Tim in his little cano! And yes, he is also looking for some birds.

In Korte- en Lange Ambacht we watched our first Jack Snipe of this year.

But here we did came for.....thousands of ducks (Wigeons up to 5000 and Teals up to 1500)

We counted also three Greater Grey Shrikes this morning! That brings the number of it to 13 for the whole NP! The best winter ever as far as we know.

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)

Seawatching in January? Yes!

Seawatching in January. Are you crazy? No, because of nice species as dark morph Fulmars, Pomarine Skuas et cetera.

Westkapelle - fltr: unknown, the hard core counters Pim Wolf (in front), Corstiaan Beeke and Thomas Luiten

Yesterday, my friend Peter Verhelst and I went to Zeeland to get some seabirds for our yearlist. The forecast of a fierce wind from NW (7 Bft) did us decide to start on Westkapelle. The sea was beautiful! We counted from 8:30-10:15 and got some nice Fulmars (including dark morph), Great Skuas (8), struggling Kittiwakes (350) and a Pomarine Skua. Unfortunately we missed a Leach Storm petrel that passed one hour later.

Great Skua (2cy) - Westkapelle - 4/1/2012

Kittiwake - Westkapelle - 4/1/2011

We continued our excursion to the longstaying Greater Yellowlegs of Colijnsplaat. There we met some guys from Swiss which were doing a birding trip for some days. After that, I can conclude I have tot improve my German... Neeltje Jans was our next stop. Thousands of large gulls are staying there for some weeks now, feeding with the many many Ensis arcuatus that came ashore. We call it the grey plague. Also some hundreds of Greater Black-backeds. And some flapping Little Gulls.
Actually, we were looking for the Glaucous Gull and Iceland Gull that are staying here for three weeks now. While looking to the grey plague, we found three Caspian Gulls (2cy, 3cy, and 4cy) and a Yellow-Legged Gull (2 cy). After some minutes, Peter found the Glaucous, swimming among the Herrings argentatus and argenteus. We tried to photograph it and suddenly, I realised I was taking the 'wrong' one. While looking through my camera, I said: 'uh, it is smaller one'. The Iceland had also appeared and passed nearby.

Grey plague

Little Gull - Neeltje Jans - 4/1/2012

During our walk to the gulls, suddenly I heard something like a falling plastic beaker. It turned out to be Peters telescope: a broken body! How sad, but we went on birding.

Glaucous Gull (2cy) - Neeltje Jans - 4/1/2012

Iceland Gull (2cy) - Neeltje Jans - 4/1/2012

Iceland Gull (2cy) - Neeltje Jans - 4/1/2012

Two in one!
 

On the Brouwersdam, we counted up to 1200 Herring Gulls with also this one. Due to the size and p5, I doubt if we can call this an argentatus or the argentatus-type omissus. Could be easily misidentified as a michahellis.

Yellow-legged Herring Gull argenteus - Note the small size, roundish head, not very bright red orbital ring and roundish white top of p10.

p5 with only a little dark spot. Less black in the outer primaries. Not the right mantle color.

At the end of the afternoon, we visited the Iceland Gull of Stellendam, an island northwards. It was waiting for some bread.

Iceland Gull (2cy) - Stellendam - 4/1/2012

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