Foraging Strategies and Their Influence on Scanning and Flocking Behaviour of Waders

Abstract

Scanning and flocking behaviour of 16 species of wader showing three different foraging strategies (pause-travel, visual continuous, tactile continuous) was studied to test predictions regarding the effect of foraging technique on such behaviours. The scanning hypothesis predicts that (1) pause-travel foraging species will spend less time vigilant and will scan less frequently than species using a continuous foraging strategy (either visual or tactile); the flocking hypothesis predicts that (2) visually hunting species (both pause-travel and visual continuous) will tend to form smaller flocks than tactile-foraging species. The results show differences between pause-travel and continuous foraging species in vigilance rate but not in time spent vigilant or in mean scan duration. The two continuous strategies did not differ in any variable related to scanning behaviour. However, with respect to flocking behaviour, both pause-travel and visual continuous-foraging species differed from tactile continuous-foraging species in foraging flock size. These results are discussed in the light of the syndrome hypothesis.