Hydro-ecological relations in the Delta Waters

of waterbirds occur regulsrly. The wst important groups are ducks,
waders, geese, gulls and tern; less abundant are grebes, cormorants
etc. For all these bim3 species, occurring regdarly, the Delta area
has a very important funetion in several stages of their life cycles.
Figure 3 Map W£
the World, showing the major migration routes of birds
occurring in the Delta area. (Horizontal hatching: major
fptertidal areas; vertical hatchins: breeding a d wintering
range qf birds using the Delta area)
Figure 3 suomlari~qs Chs migins and destinations of birds occurrim in
the Delta. In summer important numbers of breeding bads a£ several
speeies are present (Meiniqger, 1986). After the breeding season most
of these birds migrAte south, some to tPle we6.t coasts of Afrioa, lJfrile
other speties are more or less resident. Birds breeding in the .boreal.
Subatetic and arctic zone of Europe, Asia. Greenland and North America
use the Delta either as B refuelling site on migration between the
breeding areas and the wintering grounds [in spring and autumn), or as
a wintering site. Many species also moult in che heea. All bhese
species have in common a large energy denand a d are hence dependent on
an abundant food supply md low levels of disturbance. Their wcurrence
show that the Delta area acts as a turntable in large scale movements