Officially called Staines Reservoir (in the singular), this site is actually two reservoirs (North Basin and South Basin) separated by a narrow causeway. They lie just north of Staines and Ashford and south-west of Heathrow Airport. The site has been designated as a Site of Special Scientific Interest, particularly for its wintering wildfowl. Edit
Car — Most birders will drive here and parking is available on the west side of the reservoirs on the busy A3044 (Stanwell Moor Road). There is also a small car park on the east side of the reservoir (B378, Town Lane), but it is not overlooked and has acquired a reputation for theft and vandalism. If you wish to head for the east side, it may be wiser to park in a nearby residential street such as Diamedes Avenue.
Train — For public transport users, the quickest route is to use the mainline rail station at Ashford, which is a direct 20-minute walk away (turn left on Church Road and keep going straight). Staines Station is a similar distance but the route is more convoluted and also involves following the busy A3044 road.
TfL — If you prefer to use Transport for London services, take the Piccadilly Line to Hatton Cross and catch a 203 bus from Stop D in the adjacent bus station. It generally runs every 20 minutes Monday to Saturday and every 30 minutes on Sundays. Get off after about three miles at St Anne’s Avenue and you will see the reservoir in front of you. Walk forward and turn right to find the path up to the causeway. Several other local buses also serve the area, especially to Ashford Hospital near the south-east corner of the South Basin.
Open access to the reservoir is via the causeway that bisects the two basins. There is strictly no access to any other part of the reservoirs (nor the adjacent King George VI Reservoir). The causeway has become a good meeting place for birders to find out what's around in West London. It's also renowned for being windy at any time of year and plagued with clouds of insects in summer.
Great Northern Diver at Staines Res, 26.11.06 (photo by Andrew Moon). The large expanse of water is particularly attractive to divers, and one or two are seen at Staines most years.
One of the best sites in London for rarities, Staines has attracted an impressive list of species over the years including waders such as Baird's Sandpiper, Collared Pratincole, Buff-breasted Sandpiper, Sharp-tailed Sandpiper, Pectoral Sandpiper, Long-billed Dowitcher, two Wilson's Phalaropes and three Lesser Yellowlegs. However, seeing any wader here usually requires one of the basins to be drained, which seems to happen every few years. Migrant waders can be found on the water's edge when both basins are full but there is usually very little variety.
Gulls and Terns also offer the chance of at least a scarce bird for London such as Little Gull, Black Tern and Arctic Tern, all of which are regularly recorded on passage. Rarities here have included Whiskered Tern, White-winged Black Tern, Caspian Tern and even Sooty Tern — although considerable doubt has been cast over that particular record.
Seabirds can be found here when there has been a storm, such as Leach's Petrel, Pomarine Skua, Arctic Skua, Long-tailed Skua, Great Skua and Sabine's Gull. Skuas are sometimes also seen on passage.
The large expanse of water (172 hectares; 424 acres) attracts other birds, especially migrant raptors such as Osprey, Marsh Harrier, Hen Harrier and even Montagu's Harrier. Other rarities include Alpine Swift, Roller, Bee-eater, Hoopoe, Wryneck and Icterine Warbler.
The causeway often attracts passage migrants such as Black Redstart, Rock Pipit, Water Pipit and Wheatear.