The two 1km transects are broken down into 200m sections and birds are counted in zones <25m, 25-100m, and >100m on two visits, one in May and one in June.
Although the transects mainly run along the tracks through the forest, with many tall trees on either side, there are areas where timber has been harvested or there is new plantation so there are some long distance views as well.
In other places the view is very limited and birds are mostly identified by their calls or song.
My first square has yielded a total of 29 species over 12 years, with an average of 11 per year (and probably about 9 per visit). My new square has been surveyed three times in the past 12 years with a total 44 species - 21 per year (including 0 skylarks and 0 curlews).
The commonest birds in the new square on yesterday's visit were chaffinch, woodpigeon and mistle thrush. Other highlights were cuckoo (several), jay, siskin, crossbill, redpoll, red grouse, willow warbler and chiffchaff.
Here is a very distant shot of a redpoll, a bird I usually see only in the winter.
And a siskin.
At the end of the first transect a more familiar bird was waiting.
The BBS also records mammals. Near the end of the first transect this young roe buck popped out in front of me.
Because I was downwind and standing still he couldn't quite make me out and advanced down the track several times, sniffing the air. It is a very remote spot so perhaps he had never seen a person before. Eventually he lost interest and wandered off.