eBird and Citizen Science: How Your Checklists Matter
eBird began in 2002 as a joint project of Cornell Lab of Ornithology and the National Audubon Society. By 2024 it holds more than 1.4 billion bird observations submitted by millions of participants worldwide. It is the largest biodiversity database ever assembled, and its raw material comes from birdwatchers recording ordinary mornings in ordinary places. Understanding how it works — and why certain practices matter to the data quality — makes you a more effective contributor and a better birder.
Cornell Lab of Ornithology and what eBird is for
Cornell Lab's mission is to study and conserve birds. eBird serves that mission by documenting where birds are, when they are there, and in what numbers. Researchers use eBird data to model species distributions, track population trends, map the timing and routes of migration, and identify pressure points in the annual cycle where conservation intervention would help most.
The platform is simultaneously a record-keeping tool for the individual birder and a scientific instrument. Both functions depend on the same input: field observations submitted as checklists. The more complete and accurate those checklists are, the more the data is worth.
Complete checklists: why every bird counts
eBird distinguishes between incidental records — a single observation flagged without effort information — and complete checklists, where the observer attempts to record every species detected. Complete checklists are scientifically far more valuable.
When you submit a complete checklist, eBird can treat any species not on your list as an active absence: you were there, you were looking, you did not find it. That absence is data. It allows researchers to calculate detection probabilities and model population changes over time. An incidental record that says "I saw a red-tailed hawk here" says nothing about what else was or was not present.
The implication is practical: when you go birding, commit to recording every species you encounter, not just the unusual ones. A checklist with thirty common species and one rarity is far more useful to science than just the rarity flag. Duration and distance walked are also important — eBird asks for effort data precisely because a twenty-minute visit to a small patch and a six-hour visit produce different detection probabilities.
eBird Mobile: tracking and submitting in the field
The eBird Mobile app (iOS and Android) is the standard submission tool for field checklists. Open the app before you start walking, select "Start a new checklist," choose "Traveling" or "Stationary," and allow it to track your route via GPS. As you find species, tap them in. The app will flag unusual species immediately for a brief confirmation — this is not a rejection, it is a data quality check that keeps the database clean.
When you close the checklist, you submit it directly to the global database. Your route is recorded and visible on the checklist; this helps reviewers assess whether a sighting at an unusual location is plausible.
If you are birding a known eBird hotspot — a designated location used by many observers — selecting it from the hotspot list is preferable to submitting from personal coordinates, as it aggregates data from multiple observers at the same location and makes species-frequency graphs more meaningful.
Merlin Sound ID
Cornell Lab's Merlin Bird ID app includes a sound identification feature that listens to ambient audio and identifies species heard in real time, overlaying spectrograms with species names as birds call or sing. It is not infallible — it misses quiet birds and occasionally flags species that are not present — but it is a genuinely useful field tool.
Its value for citizen science is that it accelerates skill development. Birders learning unfamiliar song quickly can submit more accurate checklists, which feeds the broader data quality. Merlin is not a substitute for developing your own ear; it is a teaching tool that happens also to be useful in the moment.
Hotspot etiquette
eBird hotspots are shared locations used by the birding community. A few conventions make the system work better for everyone.
Submit checklists against the official hotspot location rather than creating nearby personal locations, unless you have a genuine reason to document a distinct sub-site. Duplicate personal locations fragment the data and make species frequency graphs less useful. If you feel a new hotspot is warranted — a site that receives regular visits but is not yet in the system — submit a new hotspot request through the app or website with a note explaining the location.
When visiting a well-known hotspot, be aware that dozens of other birders may be tracking the same species on a given morning. eBird's "Explore" function shows recent species lists for any hotspot; checking it before arriving tells you what has been found in the last few days and what you are likely to encounter.
Breeding codes
During breeding season, eBird allows observers to attach breeding codes to species entries. These codes range from "S" (singing in suitable habitat, possible breeding) through "DD" (distraction display, probable breeding) to "NY" (recently fledged young, confirmed breeding). The scale of confirmed evidence rises from possible through probable to confirmed, each requiring different observed behaviour.
Breeding codes feed directly into breeding bird atlases — regional and national surveys that map the distribution of breeding species. The North American Breeding Bird Survey and the UK's BTO/BirdWatch Ireland Bird Atlas both rely partly on eBird-format submissions. If you are birding during April through July across most of the Northern Hemisphere, adding breeding codes to territorial or nesting behaviour you observe multiplies the scientific value of your checklist.
Data downloads via API
eBird makes its data available to researchers through a public API and downloadable data packages available at ebird.org/data. Researchers can download all observations for any species, any region, or any date range. The data powers third-party tools including BirdCast (migration forecasting) and numerous academic population studies.
For the motivated birder, the eBird API also enables personal analysis: download your own checklist history, visualise your year list by month, or map your patch across seasons. The data belongs to the scientific commons, but it is also your personal field diary, queryable and portable.
Making it a habit
The birders whose eBird contributions matter most are not those who visit the most exciting sites, but those who visit the same ordinary sites repeatedly over many years. A local patch worked every week for a decade generates the detection baselines that reveal whether a species is stable, increasing, or declining. That long-term regularity is something only an engaged local observer can provide, and no amount of professional survey effort replaces it.
Browse the map to find the birding spots nearest you, then commit to recording at least one complete checklist per visit. The aggregate of ordinary mornings is what makes the science possible.