Dam End: Juvenile Great Northern Diver seen late afternoon mid reservoir area. Green Woodpecker in the Paddock. 23 Rooks around boatyard rookery. 26+ Great Crested Grebe. Gull roost at 16:00: 2000+ Black-headed Gull, 100+ Common Gull, 20+ Herring Gull, 1 Lesser Black-backed Gull, 1 Greater Black-backed Gull.