Use of visual cover by domestic fowl: a Venetian blind effect?

Abstract

Cover is a structural feature of the environment that animals can use to conceal themselves from predators or conspecifics or to gain shelter from inclement weather. Cover may also form a physical barrier limiting movement. It was hypothesized that domestic fowl,Gallus gallus domesticuswould use visual cover for concealment. Use of cover was examined in two strains of domestic fowl kept indoors in four groups of 110–112 birds each. In each pen, cover was provided by four rigid vertical panels, one in each of four quadrants. Four similar quadrants were without cover. To investigate use of cover for concealment, the four cover structures varied in continuity of visual cover: (1) transparent (0% cover), (2) transparent with four equidistant vertical green stripes (33% cover), (3) transparent with eight such stripes (67% cover) and (4) solid green (100% cover). Scan samples of quadrant use were made weekly when the birds were 24–52 days of age. Both strains of domestic fowl (1) used areas with cover more than areas without cover, (2) showed increased resting and preening behaviour in areas with cover and (3) showed increased use of cover as continuity increased from 0 to 67%. These results could not be explained by thermoregulatory or physical barrier effects of the cover structures. The results are consistent with the hypothesis that a preference for concealment motivates the use of visual cover by domestic fowl, and suggest a ‘Venetian blind’ effect for visually discontinuous security cover.