Gosforth Park - Bittern

Gosforth Park is a  Private site run by The Natural History Society of Northumbria and is only open to members of the society membership details here.http://www.nhsn.ncl.ac.uk/

A few hours in Gosforth park  Just to get out of the wind again ,usual suspects at the feeders and some Long Tailed Tits  and a Stock Dove dropped in . I had a walk to the lake area not expecting much ,more just to stretch my legs before heading home  after counting everything in sight  the chap next to me said "Bittern " on your right, camera came out and I rattled a few shots off  as it was only seen very briefly ,I should have reset my camera as I had forgot to put the IS back on and should have upped the iso as it was rather dull so I have put the shots into a slideshow on there own they are not much but together they show the bird in some sort of display? . It first stood on the reed edge then flew a few yards and started to flap rather like a young bird flexing it's wings  this it did briefly before again disappearing into the reeds . The images below are some of the better ones from the run.   

Bittern with it's wings spread neck feathers erect,threat display ? or actually just stretching it's wings ?