Effect of invasion control of waterbirds by bird–proof netting in lotus fields

Abstract

Bird–proof netting is widely used in lotus fields in Japan in order to prevent damage caused by feeding waterbirds. In this study, we examined the effect of the netting on waterbird invasions into lotus fields along with other environmental factors, using Generalized Linear Mixed Models (GLMM). We counted the number of ducks (Anatidae) and Eurasian Coot Fulica atra at night in 80 lotus fields in Ibaraki Prefecture, Honshu. Surveys were conducted six times each in spring (February–March) and autumn (October–December) in 2011. In the model analysis, the type of the netting did not affect the number of ducks or Eurasian Coot. The amount of harvest residue positively affected the numbers of ducks in both seasons, and the distance from the nearest lake negatively affected the numbers of Eurasian Coot and positively affected the numbers of Eurasian Wigeon Anas penelope in both seasons, and Mallard A. platyrhnchos in spring. Thus, netting was not an effective means of preventing waterbirds from feeding in fields. In addition to the proper installation of netting, it is important to consider the factors attracting birds to the fields.