THE INFLUENCE OF HUNGER ON FEEDING-BEHAVIOR AND ON THE ACQUISITION OF LEARNED FORAGING SKILLS BY THE 15-SPINED STICKLEBACK, SPINACHIA-SPINACHIA L

Increased hunger and associated feeding motivation increased the foraging efficiency of sticklebacks already experienced with Gammarus or Artemia as prey. Behavioural components additional to the basic foraging sequence were performed less frequently and reaction distance and speed of attack increased as handling time decreased. Foraging efficiency also increased as naive fish gained experience with prey, but the rate of learning was modified by the forager's initial hunger level. Fish deprived of food for 24 h acquired attack and handling skills faster and more thoroughly than those fed to 50 and 95% satiation. Learning increased the profitability of both Gammarus and Artemia. Whether a less profitable prey type can become more profitable than another will, however, depend critically on the prey-specific intrinsic rates of increase and decrease of handling time associated with the independent effects of learning and satiation, and on the forager's initial level of hunger. © 1991 The Association for the Study of Animal Behaviour.