(a) The temporal extent of the dataset; the histogram summarises starting sampling years of all events (log₁₀ y axis). Blue rectangles represent the four temporal periods covered by the Czech Breeding Bird Atlases (Hudec et al. 1987, Šťastný et al. 1997, Bejček et al. 2006, Šťastný et al. 2021); (b) Temporal durations of events in the dataset (log₁₀ x and y axes).