Birds come to the site for a variety of reasons - to feed, to breed, to roost, to moult, for safety from predators. The areas of open water and the islands are particularly attractive for them. Birds also come here at different times of the year. In the winter, when waters in northern Europe freeze and the ground is covered by snow, wildfowl such as ducks, geese and swans come south to the UK for water and feeding. By the spring, many of these will have gone back but others such as warblers, terns, martins, and swift, come north to breed here, returning south before winter. Others can be seen here all the year.
54 key wetland bird species have been identified at Walthamstow Wetlands between 2004-2009 as part of the Wetland Birds Count (WeBS). The WeBS count is undertaken by local volunteers, working to the British Trust for Ornithology’s methodology. Out of these 54 birds, 37 of these were considered rare including garganey, kingfisher and green sandpiper. Additional surveys are undertaken by London Wildlife Trust every fortnight to ensure the Wetlands’ conservation status is effectively monitored. The site also provides suitable nesting sites and foraging terrain for a number of terrestrial birds, in particular the trees and scrubland around reservoirs 1,2 and 3.