Figure 1From: Circumstantial evidence for an increase in the total number and activity of borrelia-infected ixodes ricinus in the NetherlandsBird population densities 1980–2008. Dots represent population index values of each bird species per year. The bird population index was calculated by dividing the number of a bird species each year by the number of that bird species in the baseline year in 1990 and multiplying the result by 100. Lines represent the best-fit negative binomial distribution with the mean (solid) and the 95% confidence interval (dashed).Back to article page