I went to Nikko center of Japan and North-west of Tokyo and observed male White-backed Woodpecker. White-backed made his rest-hole for winter near the pass. I could see easily because 20m from the pass, so close!! But many people didn't notice. Making process almost finished and he could fit into the hole. Anyway, I think we can identify White-backed and Great-spoted Woodpecker with call "kyo". White-backed's call is more sharp and strong at "k". I found 2 process of making hole.
I observed around 30 minutes. It was so good time. This pic was took from the pass the nearest place. He alarmed a little. Aging of Woodpecker is difficult. The process of the molt of wing is complex. I don't have any book about White-backed, but have about Great-spotted. From that, I think this individual is maybe adult. The spot at tip of primary is only one side, juvenile feather has spots in both side. And iris colar was flesh red, but we can't see from this pic.