Grey Heron

We have quite a few Grey Herons on the river. Some days there is one and on others I have seen up to seven, all on the far bank and some even in the trees. They don't nest here but a few miles away there is a Heronary (if that's the technical term) where they do. Haven't been there myself yet.
Last year, while out walking with FW we saw seven along the far bank all about 50 yards apart. They all appeared to be headless and standing on one leg completely motionless. Thought at the time someone was playing a trick and postioned some dummy ones. Eventually FW saw one move to confirm that they were 'alive'. Never seen so many at one time since that day, was quite a sight to see.