Figure 4. Plot illustrating the predicted effect of the crop
plant type diversity (SHANG), the proportion of farmland surrounding the
singing group (AGRI5) and the proportion of bare ground within the
singing group’s range (BARE) on the population growth rate of Ortolan
Bunting. The black thick line represents the conditional prediction for
Uusimaa region, with a 95 % confidence interval around it (grey area),
when TERPRE is kept constant at 1. Scattered circles illustrate the
distribution of singing group growth rates averaged over time. This
averaged data was generated by first adding 0.5 to the territory count,
both the current and previous year (TERRI and TERPRE), and then
aggregating the data by singing group and counting the average change in
population growth rate and the average for each of the three
environmental variables. The intensity of the colour of the circle
indicates how many times that singing group was visited on consecutive
years, i.e., how many observations were available for estimating the
growth rate for that singing group (n = 1–13, mean = 2.8).