Lots of activity from the Nuthatches at the moment as they hold down territories and set up homes for the Spring. There seems to be a constant calling in the Bollin Valley near to where I live. They are a super looking bird and one of my favourite woodland birds. Probably only beaten by woodpeckers.
If you have trouble seeing them, they will help you out at this time of year. Calling frequently, and allowing you to pick them out as they scurry around the trees, quite often upside down.