Any  idea about the drivers for this enormous influx? Weather? Food? Breeding succes? Expanding breeding range?

Difficult at the moment clearly indicate the main reason of influx, probably strong easterly winds in the early October, see: 

http://www.ornithomedia.com/magazine/analyses/afflux-accenteurs-montanelles-europe-ouest-octobre-2016-02301.html

Most probably weather. Probably not winds that much though - might have more to do with exceptional high pressure / low pressure areas.

Please update the last line of your post (where you mention the Netherlands still needs one), and can you include a link to the google map with sightings of Siberian accentor (I reckon you know about that map)?

The map is available in the last sentence - click on 'totals stand on 148'.

Nice overview Lukasz, thanks. I don't know who made the (fantastic!) map, but it seems like one record is missing: at Ventes Ragas, Lithuania they've trapped two birds this year, on 14 and 24 October. I only see the one from the 24th on the map (and the dot is not on the right place either: the ringing station is not on the spit, but on the eastern shore of the lagoon). Any new records from yesterday (27th) that anyone knows of? Cheers, Vincent

Thanks! Soon, we will update the map and the text with new records. Today, the first this autumn (and second ever) for Czech Republic.

For anybody who'd already like to know: now 206 at least (by tarsiger on twitter): 202 SIB ACC 4th-4th Nov: SWE(68), FIN(63), GBR(12), POL(11), DEN(10), GER(10), NOR(9), EST(7), LAT(6), LIT(4), NED(1) and CZE(1) and another group of 4 at Turku, Finland. Im looking forward to the updated article and the map Lukasz!!

The map is regularly updated (new records, exact locations) with some great help of Magnus Hellström (Sweden) and Mika Bruun (Finland / Tarsiger.com). Please let me know if you still see any errors or have additional information. 

The graphs are missing a bird from 27th October when two new birds were found; one in Sweden and one in Finland (Source: Tarsiger.com)

Hi Mark,

On 27 October was one new bird in Sweden (was included on a figure). The second from Finland mentioned by Tarsiger was seen for the first time on 20 October.

Here are 8 Latvian records so far - 5 trapped, 3 observed:

1. Lauteri, 15th October, 1 trapped for ringing.

2. Lauteri, 15th October, 1 trapped for ringing (second bird same place 30 min later).

3. Jurmalciems, 16th October, 1 trapped for ringing.

4. Ainazi, 16th October, 1 trapped for ringing.

5. Liepaja, 19th October, 1 observed.

6. Pape, 26th October, 1 observed.

7. Ainazi, 4th November, 1 trapped for ringing (second bird same place)

8. Jaungulbene, 8th November, 1 observed.

Page with exact locations on Google Map - http://ornitofaunistika.com/lvp/prumon.htm

Many thanks Agris! It seems that this madness is coming to the end ;-)