Hydro-ecological relations in the Delta Waters

are determining the dfstrlbution af birds in che Delta r2s well. NeM to
ecolo@cal factors mch es ppulatiob. size, arlgracian partem and diet
selecriob. human arrivities affect bir&i, often negatimely, in a
varietg of nays. Disttubailce, poLlution artd habitat loss are Lnnoediate
threats. Several tomagament options are available and discussed in
Drder Ca inpmve the acologlcal cwditions.
Gver Ehe l46t tws deeaaes the wealled Delta ,a-
?n fhe asu~hwsrern
part of the Netherlands has changed profgunLUy. 14 this area $he rivers
~Wn. W and Sehdde £lea ineo B& sea thrangh e cosplelt s.p%em of
estuaries.. Is respanwe to the disastms etcrro £l@od of 1953, in whim
.aaSut l:&O.O people were killed, as BBlbfti~als plan @>E aalm@
up all ~ht
me e$tcr&i~e$ was deedoped. In 1-967 the &.xec&ion of this plan,
&Ithod& @rptte8 id the b&Se
Df tHe yeais, s s mleted. ThLs
~ ~ u h tn e d ~profalrnd chaages kn thil eelbgieal relatims, as lilrge
't:idal .&reds di&p$ear@d and ~ e habitatir, w such as stagnant saline wd
bi&.kish lekes, were cr-ed.
5ie.c~ d$.scxibieg all these eeolsggtcal
chrtng*~ is fmpossible. In $his paper W@ shall reetrict eu~selves to
descLlibe tibw tha oeeu.s.r?nce and d~i.@%ribation o* birds wer zhe
aiffereat basin9 Changed and xe isdieate reia%imxv with food suppigi and
otber faceors.. W.@@, the area is? very imparranr for btsds apt is^,
et al, 198&; Saeijs a~d Baptigt, 1~91771 d., as the gentgal pwblle is
sepsAtive tg birds, the7 haye p.byzld a relatfvely ~ortanc role in
deci.s:i@ndiug (ens. in eke disewasian sht at spen or closed
b,mte~sBhel@e: d~riqg the Uo6sre-s #f the Philips- and OeatettBni; in
tbe eurrent dbcusriori abwt rhe &its to be @et or reeteatilbn in
Oasfemchelde erc.l.
Xn the fiei.wt part of thfs papixr ttie Wbitati in the De'lyta area
and the ohsewed chaQgesia tht?. occnrt-ence ef waferbird% are descritred.
In the: saEBnil p&
some fwtoes inflmencing tiiis obse.md distTibutan.
bein$ Toad BUatLability and ~nat?Xp btber fac&ors as migration pattwns.
pdpwlatton bize and thlaran fiite&ereuce are Wyxed.