eventDate (http://rs.tdwg.org/dwc/terms/eventDate) @return [String] Relevant temporal context for the distribution record. Preferably given as a year range or single year on which the distribution record is valid. For the same area and taxon there could therefore be several records with different temporal context, e.g. in 5 year intervals for invasive species. Example: "1930"; "1939-1945"