Largest citizen-science birdwatching project

Since its official launch in 2002, eBird - an internet-based community science project managed by the Cornell Lab of Ornithology in Ithaca, New York, USA - has archived more than 81 million bird checklists and over 1.1 billion species observations. During its busiest month on record to date (May 2021), eBird received 1,775,616 separate birding checklists, which reported 28,597,810 individual species observations.

eBird surpassed the milestone of 1 billion bird observations in May 2021. The 1-billionth bird observation was an Australasian swamphen (Porphyrio melanotus), reported on this checklist by Australian eBirder Heidi Krajewsky during Global Big Day 2021.