Figure 2.

Avian influenza virus (AIV) prevalence in dabbling ducks and gulls. AIV prevalence from August to December according to A) year and B) month in 1709 dabbling ducks and 708 gulls sampled in the south-west of Norway. Samples were pooled according to month. The surveillance in gulls started in 2006. No samples were collected in 2008. Annual influenza A virus prevalence is also presented according host species, with mallard, common teal and Eurasian wigeon shown in C) and common gull and herring gull (n = 622) showed in D). Binomial 95% confidence intervals are indicated by the bars (A-D).