Individual variation in anti-predator responses in the Three-spined Stickleback (Gasterosteus aculeatus L.).

Abstract

Inter-population differences in stickleback anti-predator behaviour in responses to predation risks are now well established (HUNTINGFORD 1982; GILES & HUNTINGFORD 1984). This paper re-analyses this data in search of individual behavioural differences in the exploration of a novel environment and escape strategy shown by sticklebacks when stalked by a hunting pike (Esox lucius). 8 factors (accounting for 70% of the variance in the original data) emerge from the analysis and significant sex and population effects are described. Factors 1 and 2 correspond to predator investigation and the level of boldness shown towards pike. Factors 3, 4 and 5 separate the escape response into three distinct tactics adopted by sticklebacks when being stalked by the pike. These behaviour groupings are independent of the activity of the stickleback before the presence of the pike is detected. Factors 6, 7 and 8 were comprised of activities (use of open water, of weed beds and of the cover provided by the bottom of the tank) which load heavily for both the periods before and after the sticklebacks reacted to the predator. These groupings may represent different anti-predator tactics adopted by individual sticklebacks.