Open water
Plainly the most significant habitat, and takes up over 80% of the
site. Importantly, variations in depth and water chemistry allow for a
range of ecological niches. Deeper, nutrient poor lakes like Rockford
attract diving ducks, while dabblers like Wigeon and Teal are commoner
on eutrophic, shallower bodies such as Ivy Lake. Ibsley Water is the
largest and probably best-covered lake (with three hides overlooking
it), and is the location of the major nightly gull roost. Black Terns,
Little Gulls, Black-necked Grebes and the majority of site rarities are
found at Ibsley Water.
Gravel shores and islands
These provide roosting and feeding sites for waders, wildfowl and
gulls, and a crucial nesting opportunity for species like Little Ringed
Plover and Lapwing. The shores and islands of Ibsley Water have turned
up the majority of recent records of migrant waders, and several rarer
gulls.
Grassy swards
The grassy fringes of several lakes, notably Ibsley Water and Rockford
Lake, can be important for grazing geese and Wigeon, plus migrant
wagtails and similar.
Lichen heath
While not of particular significance for birds, the very unusual habitat
around the Southern Water pumping station (and elsewhere) is worth
noting. On top of concrete footings from the old RAF Blashford, the
habitat is sharply drained and gets very hot and dry in summer. It is
home to numerous scarce and rare plants and insects.
Alder/willow carr
Wet woodland, some of it retained in an early successional state, is
important for roosting, feeding and nesting passerines. Tit flocks are
worth checking in autumn/winter - both Yellow-browed Warbler and
Siberian Chiffchaff have been found in recent years.
Mature trees
There are no large blocks of mature woodland on the site, but the
scattered mature trees harbour hole-nesters such as Tawny Owl and Stock
Dove, and woodpeckers. The ongoing dieback of Ash may well provide more
opportunities for the latter. (Worthy of note is a huge, healthy Elm
tree on Ellingham Drove, right opposite the main entrance to the
Visitor Centre.)
Running water
Two streams run off the New Forest and through the site to the River
Avon - the Dockens Water and Linbrook. The former is of international
importance as an example of an acidic spate stream flowing into an
alkaline sourced main river. Both are prone to rapid rises in level
after rain, and summer drought, during which the Linbrook regularly
runs dry. Kingfishers and Grey Wagtails are characteristic species of
these streams.