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Fig. 4. Intake rate in experiment 2 as a function of gizzard size class (values are
means ± S.E.M.). Open circles indicate a soft diet of
unshelled mussels was offered; closed circles, a hard diet of with-shell
mussels was offered. The broken line gives observed handling rate
(1/H). The broken diagonal line gives the intake rate for with-shell
mussels predicted from shell mass, gizzard size and regression coefficients
obtained in experiment 1. The grey bar gives the postulated maximum
metabolizable energy intake rate [average of Kirkwood
(1983) and Kvist and
Lindström (in
press)].