Communal roosts: there are six Fritillaries in the above image, five of which have gathered to bask whilst there are seven in the long grass roost in the image below.
At least four large colonies exist locally with Hockley Woods and Dodds Grove being the more well know, however Little Haven and Pound Woods are also very good locations, i.e. 344 at Little Haven on 6th June 2009. The following images are from these colonies with the first two shots from Little Haven.
Heath Fritillary, Little Havens EWT Reserve, Essex
Early-mid June 2009 saw a glutton of Heath Fritillaries at Little Haven EWT Reserve: the following three images are from here taken on 12th June 2009.