Annual BBS counts of six species of birds on ten states and annual WNNID reports, by state. The color of the lines that connect counts indicates bird species: AMC = American Crows; AMR = American Robins; HSP = House Sparrows; NC = Northern Cardinals; BJ = Blue Jays; MOD = Mourning Doves. The tick mark on the secondary y-axis indicates the maximum annual incidence per 1,000,000 of WNNID in a state (red bars).
Foppa et al. BMC Veterinary Research 2011 7:43 doi:10.1186/1746-6148-7-43