waders and their estuarine food supplies - Vlaams Instituut voor de ...

PREDICTING SEASONAL AND ANNUAL FLUCTUATIONS IN THE LOCAL EXPLOITION OF DIFFERENT PREY
in the winter of 1977/78, which the Oystercatchers
were indeed observed to do (Zwarts & Wanink 1984).
The low mortality rates of Cockles (Fig. 8B). Scrobicularia
(Fig. >)>>.) :.:: :•; 'Fig. 10B) also -uggested
that these aliernalive prey were either not, or
hardly ever, taken.
(2) After the growing season of 1978. Mya lived beyond
the reach of Oystercatchers and the birds were
expected lo Iced on Cockles Intensive observations of
Hulsman (unpubl.) between March and November
1978 showed that the Oystercalchers did indeed take
Cockles. The birds achieved an intake rate of 1.49 mg
s"' (Zwarts et al. 1996b). which was close to prediction.
(3) There was a mass mortality of the Cockles in
lale autumn 1978 and none was -still alive after the severe
vv inter of 1978/79. Therefore, only Scrobicularia
3.5 - 0 Cerastaaerma /T\
mMacoma \*J
»Scrobiculana Jk
3 3.0
c
I 2.5
II ^**.
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