EBird

The everyday workhorse of bird research. You go birding anywhere, for as long as you like, and submit a checklist of what you saw and heard; a ten-minute lap of the local park counts as much as a day at a refuge, as long as you note when, where and how long you looked. Those checklists add up. A 2025 study in Science drew on 36 million eBird observations to map population change for 495 North American species and found that birds are declining most steeply where they are most abundant. Once you have an account, the big seasonal bird counts that run through eBird take no extra setup.