Presence of avian influenza risk birds in and around poultry free-range areas in relation to range vegetation and openness of surrounding landscape

Free-range areas contribute to the welfare of poultry. Chickens are most likely to use these areas if there is sufficient cover by trees. However, wild birds in free-range areas may infect the chickens with avian influenza (AI). This study aimed to investigate the relation between the presence of AI risk birds and woody vegetation within the range areas as well as in the landscape surrounding the range areas. During two seasons all wild birds were counted in the free-range areas of 11 poultry farms and their immediate surroundings. More high-risk birds were observed in free-range areas with less than 5% woody cover, compared to free-range areas with more woody cover. Furthermore, more high-risk birds were observed in the surroundings of free-range areas in open landscapes, compared to half-open landscapes. As for low-risk birds, no relation was found between woody cover or openness of the landscape and the presence of these birds in free-range areas or surroundings. However, interpretation of the results was hampered by the incomplete factorial design, which did not allow to differentiate between the effect of woody cover within the range area and openness of the surrounding landscape. The results of this pilot study need to be confirmed with further experimental research on the relation between the presence of AI risk birds and woody vegetation in and around poultry free-range areas.