Citizen Science datasets on GBIF plotted with all other (gray) GBIF datasets (>100K occurrences). There are many citizen science datasets with millions of occurrences (eBird, (Swedish) Artportalen), and the top 3 datasets on GBIF are all citizen science datasets. But in terms of number of unique species, only iNaturalist competes with large museum datasets like Smithsonian NMNH.
Because of very large datasets like eBird and Artportalen, Citizen Science makes up a large percentage of the total occurrence records on GBIF.
Also mostly because of eBird, 96% of bird-records (Aves) come from Citizen Science datasets. Similarly eBird (with >500M records) also makes up most of the Kingdom Animalia occurrence records. Less than 500 citizen science datasets make up 36% of insect (Insecta) occurrence records on GBIF.
What percentage of GBIF-species have citizen scientists re-discovered?
Note: This does not mean the re-discovery was unique to citizen science datasets.
I chose to use only species on GBIF with at least 1 occurrence record instead of the GBIF backbone taxonomy, as many named species do not have any occurrences on GBIF see previous blog post and here. It must also be due to some differences in naming conventions between eBird and some other GBIF datasets, that results in only 70% Aves coverage. I have also excluded fossils from this graph.