How Flockline uses eBird sightings

What Flockline is for

Flockline is for birders who want a quick map of recent reports, a view they can share, or a short weekly selection to browse. Choose a species, states and dates, then open the original checklist for the observer's account. Where historical data is available, we add local seasonal reporting frequency with its source and sample size.

eBird provides the underlying records and a broader set of exploration and recording tools. Flockline's weekly selections are automatically assembled from those records. For editorial interpretation of significant rarities, the ABA Rare Bird Alert offers a different kind of report.

Where the data comes from

Every sighting comes from eBird , the citizen-science database run by the Cornell Lab of Ornithology. Birders submit checklists of what they saw and where. Flockline reads that data live through the eBird API, so the map reflects what people have actually reported in the last few days, not a fixed dataset.

Reading the map

Pick a species from the title at the top, a window from the presets at the left, and states from Filters. Each dot is a location where that species was recently reported, colored by how recent the report is: blue for older, gold for mid, red for freshest.

The timeline

The scrubber filters the latest report from each location by date. It does not track individual birds or reconstruct their movement. The two modes show different views of those same records.

• Trail shows locations whose latest report falls on or before the selected day, colored by recency. Earlier reports at the same location are not included in this feed.
• New shows only the locations whose freshest report is the selected day, so you can watch fresh detections appear day by day. The bars above the rail count those locations for every day in the window.

Choosing a region

Nationwide selects all 50 states plus Washington, D.C. in one step. The other four presets follow U.S. Census groupings: Northeast, Midwest, South, and West. Choosing one selects every state in it, and the state buttons refine that selection. First visits start Nationwide, and links that name a region or states open exactly that selection. The map, timeline, Insights, and Ask all work at every scale.

The nationwide map feed sometimes omits a report's state. Its coordinates still place it on the map, but Flockline shows “State not supplied” instead of guessing from a nearby state. State-specific requests provide that context. Ask can also recover a public hotspot's state from eBird's exact location record.

Read the data honestly

These reports reflect where birds were detected and where people looked. They are not a population survey.

• Reports are observations. Species differ in how easily they can be found and identified. Counts also depend on time spent looking, habitat, weather, and the number of observers.
• Review status is separate from rarity. Records can be accepted by eBird without individual review. A flagged report may await review, and an accepted report does not establish that a species is rare across an entire region.
• Coverage is uneven. Well-birded hotspots and weekends produce more reports than remote areas and weekdays. Empty space on the map often means nobody was looking, not that nothing was there.
• State requests can fail independently. Flockline loads a large region a few states at a time. If eBird is temporarily unavailable for one state, the successful states stay on the map and a partial-results notice names what is missing.
• Provisional reports. Including provisional reports adds sightings that eBird has not marked valid. Toggle it off in Filters to request only records marked valid. Validity does not mean every record was individually reviewed.

Insights

Insights and weekly roundups select reports from eBird's notable-observations feed. A report is flagged in its local and date-specific context; the species may be an expected seasonal visitor or familiar elsewhere. Flockline uses recency and geographic variety to select reports. Historical context is shown where a county baseline is available; it does not rank biological rarity. Short summaries use factual templates, not generated interpretations, and preserve the source's review status when available.

Report counts come from distinct eBird checklists. Flockline groups reports of the same species at the same place and start time to reduce duplicate copies of shared checklists. This feed does not include eBird's shared-group identifier, so the grouping is an estimate, not a count of independent sightings. Different groups can still report the same birds. A bird count beside a place belongs to the featured checklist.

Nationwide Insights uses one bounded country feed so a useful selection loads quickly. If eBird's result limit is reached, the panel says that coverage and report totals are incomplete. Weekly roundups make additional state requests to extend coverage; they still disclose failures and limits. Neither selection is an exhaustive alert service.

Scope and shareable links

Insights carry their own region and window, separate from the map. By default they follow whatever the map is showing; pick a region or a different window inside the panel and they stay pinned to it. The link button copies a URL that reopens Flockline directly on that exact view, so "notable reports in the West over the past three days" is one link.

Historical context

Historical context covers all eight Connecticut counties, San Francisco and San Mateo counties in California, New York County (Manhattan), and Suffolk County in Massachusetts, using eBird's official histogram downloads for 2016–2025. For each featured report, Flockline looks up that species in the county and seasonal period of the observation. Where available, the percentage is the share of complete checklists reporting the species, with all complete checklists in that period supplying the denominator. It is not calculated from the recent notable feed.

eBird exports four periods per month: days 1–7, 8–14, 15–21 and 22 through month end. We show the percentage, complete-checklist sample size, years and county together. A county average does not describe every habitat or hotspot. Low reporting frequency alone does not mean rare: seasonal visitors and habitat specialists may be expected despite appearing on a small share of county checklists.

Some histogram values can indicate occurrence from incomplete checklists rather than an exact reporting percentage. The export does not distinguish that marker from a genuine frequency of the same value. We withhold the percentage in those cases and link to the original history. This correction also applies when displaying older saved reports. The original downloaded values are preserved. Research describing this convention.

For all twelve covered counties, separate annual exports also show which years contain reports in the same seasonal period and across the whole month. These scopes are labelled separately: a seven-day window may miss reports elsewhere in the month. Each year links to its source chart and checklist sample. Positive values, including occurrence markers, document reports; explicit zeros and missing data are shown separately. Missing species rows are unknown, never converted to zero. This is a record of reported occurrence, not a return probability or rarity score.

The pooled export cannot establish recurrence across individual years or whether a flock count is unusual. Sample size is descriptive; it is not a calibrated confidence score. Reporting also depends on observer effort and repeated visits to known birds. Missing counties or species are labelled unavailable, never treated as zero. Only baselines ending before the observation year are used. Annual evidence is matched to the pooled edition's county, taxonomy and year window. Broader annual coverage and interpretation require additional historical imports and validation.

Source data © eBird and its contributors. Each report links to its county source. See the source charts for San Francisco, San Mateo, New York County and Suffolk County, Massachusetts; eBird's frequency explanation and data terms.

My birds and field alerts

My birds is a device-local watchlist. Field alerts compare watched species against the current notable-sighting findings and appear inside the app. They are not push notifications and do not guarantee that every report will be surfaced. Watchlists, alert choices, preferred states, and filters stay in your browser and are not attached to an account.

Ask

The Ask assistant answers questions about birds and their recent activity. It is designed to use the live eBird API through tools for species lookups, recent and notable sightings, and sightings near a point. AI answers can still contain mistakes; check the linked source before relying on a sighting or interpretation. When you ask to see a bird, it can load that species onto the map and zoom to a reported spot. Ask uses your selected states as its regional focus. If you say "near me" without naming a place, it asks for a town, park, ZIP code, or coordinates instead of assuming your location.

Freshness

Sightings are cached by state for about five minutes so the map stays quick and overlapping regional searches can reuse work. The refresh button in the top-right forces a live re-pull from eBird, bypassing that cache, when you want the very latest. Insights have a longer cache because they summarize a broader set of notable reports; the re-run button inside the panel refreshes the selection.

Privacy and shared links

Flockline does not require an account. Your active bird, states, timeline window, filters, open panel, and any pinned Insights scope are stored in the page URL so the view can be bookmarked or shared. No API credentials are ever stored in the browser. My birds and display preferences stay local to the device and are never sent with Ask questions. Questions submitted through Ask are sent to Flockline's server and to Anthropic to generate a response, so do not include personal or sensitive information in a birding question. If you subscribe to a weekly roundup, your email address and selected regional editions are stored by Resend for delivery. Flockline sends a confirmation link before adding the address, and every digest includes controls to change editions or unsubscribe.

Attribution and limits

Flockline is a viewer for public eBird data and is not affiliated with eBird or the Cornell Lab of Ornithology. It is meant for exploration and casual planning, not as a scientific survey. Sighting data is © eBird and its contributors. For the authoritative record, explore eBird .