This is a pretty Woodpecker, and yes, I say pretty, because this is the female. Most birders visiting Thailand miss this bird as it is hard to see outside of its habitat zone. It can be seen at the lower levels of Doi Inthanon but much more readily at Mae Ping National Park in the North which is located 2 hours South of DI. I don't get to visit that park very often though since it is so far away. I had heard that the Black-headed Woodpecker is found at Huay Kah Kaeng wildlife sanctuary in the province of Uthai Thani only a 3-4 hours drive from Bangkok. On my way back from visiting some destitute Burmese children in Mae Sot I made a point to go by.
The dry dipterocarp forest was in a healthy state and birds seemed to be everywhere. Stalking the WP who often fly around in small groups was not easy. I simply couldn't get any decent shots.
Then I found a group of them around the headquarters of the sanctuary and they were more accommodating. The birds have a very distinctive, undulating and yelping laughter. They show a bright red rump as they fly around.
I didn't get any good shots of the male with its bright red cap but that gives good enough reason to go back there sometime.