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

Investment in vigilance with respect both to group foraging and distan ce to obstructive cover was studied in the teal. The effects of group size on vigilance level were examined after controlling for several po tentially confounding variables. In a pair-wise analysis, investment i n vigilance decreased with increasing group size. Distance to cover ha d a non-linear effect on vigilance; scan length was at its shortest at an intermediate distance and longest at the longest distance to obstr uctive cover. The association between group size and vigilance remaine d 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 th e effect of neighbour distance, whereas neighbour distance had an effe ct of its own after controlling for group size and distance to cover.