Prey species have different morphological and behavioural adaptations to escape their predators. In this paper we review how these prey defenses affect prey profitability and intake rate for one predator, the Oystercatcher. Four rules govern profitability. First, within each species large prey are more profitable than small prey, because flesh content increases more steeply with prey size than handling time. Second, soft-bodied prey, such as worms and leatherjackets, which can be swallowed whole, are much more profitable than armoured prey, such as bivalves, which Oystercatchers have to open before the flesh can be extracted from the shell. Third, heavily armoured surface-dwelling prey, like Mussels and Cockles, are the least profitable prey of all, even if the armour is bypassed through stabbing the bill between the valves. Fourth, within the burying prey species, the profitability of prey decreases with depth. Hence burying bivalve species that bury in winter at larger depth than in summer, are in winter, if not our of reach of the bill, anyway less profitable. Despite the large differences between the profitabilities of the various prey species, the intake rates do not differ much when the prey species are com pared, presumably because prey with a low profitability are only exploited if the search time is relatively short, i.e. if the density of harvestable prey is high. On the other hand, within each species, the intake rate goes up if larger, more profitable prey are taken. Thus, if the birds have to feed on smaller prey specimens, they fail to fully compensate for the low profitability by an increase in the rate at which these prey are found. Although the profitability of prey differs seasonally due to the variation in the prey condition, only a small seasonal variation in the intake rate was found. Because burying bivalves and soft-bodied worms bury deeper and are less active in winter, Oystercatchers necessarily rely on bivalves living at, or just beneath, the surface at that time of year.