GM Svidler's Headwear

Watching the official broadcast for the Moscow Candidates tournament, I thought the player cartoons were wonderful the first time, interesting the second time, then I quickly became tired of their endless recycling. Same for the ads. I saw the Peter Svidler cartoon twice today and wasn't even present for the entire broadcast. Here's a screen capture...

...What is GM Svidler wearing on his head? In 2007, it's obviously Mexican; in 2011/2014, it must be Siberian; in 2013, there's nothing on his head (Is he playing polo? Croquet? Something else? 'With mallets toward none'?); in 2015, it must be Azerbaijani (Is that some kind of a fur hat?).

A big thanks to the cartoonist!

Legend (links to my site): 2007 World Championship, Mexico City; 2011 World Cup, Khanty-Mansiysk (Siberia); 2013 Candidates Tournament, London; 2014 Candidates Tournament, Khanty-Mansiysk; 2015 World Cup, Baku (Azerbaijan); 2016 Candidates Tournament, Moscow.