GROUP FORAGING, DISTANCE TO COVER AND VIGILANCE IN THE TEAL, ANAS-CRECCA

Investment in vigilance with respect both to group foraging and distance to obstructive cover was studied in the teal. The effects of group size on vigilance level were examined after controlling for several potentially confounding variables. In a pair-wise analysis, investment in vigilance decreased with increasing group size. Distance to cover had a non-linear effect on vigilance; scan length was at its shortest at an intermediate distance and longest at the longest distance to obstructive cover. The association between group size and vigilance remained after controlling for the effect of distance to cover. Investment in vigilance also decreased with the proximity to neighbours. Group size per se did not affect the level of vigilance after controlling for the effect of neighbour distance, whereas neighbour distance had an effect of its own after controlling for group size and distance to cover.