Publication bias
The funnel plots were symmetric for body size and pollination service
provision (Fig. S7, Table S5). Although the funnel plots of pollinator
abundance and activity length were asymmetric
(Fig.
S7), the regression estimates using the Trim and Fill method did not
change. Pollinator richness changed from significant to not significant;
however, the fail-safe number (N = 12 053) is much higher than the one
required (N = 745), indicating that publication bias can be safely
ignored (Table S5). We interpreted asymmetry in funnel plots carefully
given the small sample sizes e.g., for activity length, or the lack of
bidirectional outcomes for the effects of urbanisation on some
variables, e.g., pollinator richness, which have been found to decrease
across a lot of study systems, and thus will inevitably lead to a biased
plot.