AN INTERDISCIPLINARY APPROACH TO THE STUDY OF FORAGING BEHAVIOR IN THE PREDATORY GASTROPOD, NUCELLA-LAPILLUS (L)

Nucella lapillus is an ideal subject for investigating general aspects of foraging behaviour under field conditions. When foraging, it moves short distances and feeds principally on barnacles and mussels, takin g from several hours to days to handle each prey item. Consequently, m arked snails can be followed daily and accurate diet histories compile d. Such studies reveal great variation in foraging behaviour, both wit hin individuals at different times and among individuals during any on e period of time. This variation can only be explained by a comprehens ive account of endogenous and exogenous factors, requiring combined ph ysiological, behavioural, ecological and genetical approaches. Dynamic programming is a modelling technique that readily accommodates such a n interdisciplinary approach and we have used it to examine the effect s of endogenous (gut fullness, level of energy reserves) and exogenous factors (perceived risk of mortality) on the foraging behaviour of N. lapillus. While these factors account for a significant proportion of variation in the foraging behaviour of N. lapillus, there remains muc h that is not explained. We suggest that the cycle of resource allocat ion to reproduction and its interaction with risk of mortality when fo raging will prove to have an important influence on the foraging behav iour of this intertidal gastropod.