La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Vigilance during feeding and preening in coots Fulica atra
Auteurs :	Christoph Randler, Auteur
Type de document :	Article
Dans :	Vogelwarte (43(3) AUG 2005)
Article en page(s) :	189-193
Langues:	Allemand
Résumé :	During both feeding and preening, coots Fulica atra regularly interrupt their activities to visually scan their environment. This behaviour is considered to be used for detecting predators. Animals in groups lower their individual vigilance since they benefit from other animals' vigilance ('many-eyes-hypothesis'), from the 'dilution-effect', or because they compete for a limited amount of scarce resources. When competition for scarce resources should at least partially contribute to the decline in vigilance during an increase in group size, then preening coots should show a higher vigilance, given a constant flock size and a constant nearest neighbour distance. Data were collected during three winter seasons. I recorded the number of scans during one minute of foraging on land and during preening. Scans were defined every time when the focal bird interrupted its actual activity to look up. I regressed nearest neighbour distance and flock size either within a 10 m or 20 m radius against vigilance. Afterwards, I found a higher vigilance rate in preening coots supporting the competition hypothesis. However, other effects may have contributed to these result, e.g. different body postures or a reduced visibility during preening.

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