Vigilance during Preening in Coots Fulica atra Christoph Randler University of Education, Biology and Didactics, Reuteallee, Ludwigsburg, Germany Abstract In birds, vigilance during feeding is usually linked with (1) the many-eyes- hypothesis, (2) the dilution effect, and (3) the intraspecific scramble competition hypothesis. To exclude competition for resources as a driving force in vigilance research into activities other than feeding is necessary. Additionally, variables such as nearest neighbour distance and position within a flock are supposed to influence vigilance and vigilance of singletons should be compared with vigilance of flock members. I studied vigilance during preening in Eurasian Coots (Fulica atra) and counted the number of scans per minute. A total number of 117 coots were sampled with 16 of them preening alone. Coots preening alone showed a significantly higher scan rate. I found a significant negative correlation between vigilance and flock size while nearest neighbour distance correlated positively with vigilance. Further, vigilance was higher in individuals at the edge. A general linear model using nearest neighbour distance and flock size within 10 m as covariates also revealed a significant influence of flock size but not of nearest neighbour distance. The centre-edge effect still remained significant. These results indicate that flock size is the most influential predictor of vigilance in preening coots, followed by spatial organization. However, using nearest neighbour distance instead of flock size also produced a significant model as did the flock size measurement within a radius of 20 m. As scramble competition could be ruled out, the flock size effect may be indeed related to predation. Correspondence: Christoph Randler, University of Education, Biology and Didactics, Reuteallee 46, D-71634 Ludwigsburg, Germany. E-mail: randler_ christoph@ph-ludwigsburg.de Introduction During feeding, birds frequently look up within different time intervals to visually scan their surrounding environment (Bednekoff & Lima 2002; Beau- champ 2003a). This behaviour – labelled vigilance – is inversely correlated with flock size (for reviews see Elgar 1989; Roberts 1996; Treves 2000; Beauchamp Ethology 111, 169—178 (2005) Ó 2005 Blackwell Verlag, Berlin