Northern Eggars in Bryn Pydew

Was up in Bryn Pydew yesterday and saw over 20 presumably Northern Eggars almost frenzying on a section of hawthorn hedge.  A couple had faded and were on the ground, others were getting caught among goose grass but they were generally going into the middle of the hedge, the noise of it all was a bit strange.  Didnt get chance to check the NWWT reserve but worth a look too.