In total nine nests were visited with professional tree climbers who lower the chicks to the ground to be processed before returning them safely to the nest.
The chicks were processed at a field station set up near the nest site. They are weighed and their wings measured before fitting BTO leg rings and wing tags if they are large enough. Note how the chicks play possum.
This year's wing tag colours are pink on the left wing which indicates the bird fledged in the north east of England and white on the right wing which is the year colour for 2020. The wing tags helps identify birds once they have left the nest. Subsequent observations help determine survival rates and where birds disperse..
The above photograph shows a brood of three. The chick in the top right hand corner was too small to fit wing tags to and was ringed only. A total of sixteen chicks were ringed and wing tagged with a further seven ringed only.
S1 is one of a brood of four chicks, the other three chicks were ringed only. Broods of four are rare , this is only the third record for the north east, the last one was in 2015.