Fig. 3

Change in abundance as a function of change in date of first flight: species that shifted to an earlier date of first flight (negative values on the x axis) during the years 2008–2016 were species that increased their overall abundance (positive values on the y axis) (Pearson correlation = − 0.50, P < 0.001). Symbols represent dependency on irrigated areas, as follows: circles, essentially independent of irrigation; squares, use irrigated, non-native hosts in some areas as well as native, non-irrigated hosts; triangles, use irrigated, non-native hosts in at least one of multiple generations; diamond, completely dependent on irrigated, non-native hosts (there is only one species coded with a diamond: Agraulis vanillae, not native to the area). Categories of irrigation dependence are not significant predictors of changing abundance, either considered in a model with change in date of first flight or alone (F_3,39 = 1.60, P = 0.21)