Sources and Identification Criteria

This page explains where our information comes from and exactly how the Bird Finder filters are assigned, so you can judge them and correct us.

Where the facts come from

1. Cornell Lab of Ornithology. All About Birds and Birds of the World, for identification, measurements, habitat, diet, behavior and voice.
2. National Audubon Society. Audubon Field Guide, as a second reference on description, range and conservation context.
3. IUCN Red List. The global conservation category for each species.
4. US Fish and Wildlife Service and US Geological Survey. Federal protection, status history and monitoring.
5. American Ornithological Society. English and scientific names and classification.
6. eBird. General patterns of range and seasonal occurrence.

Every species page lists the sources used for that species. We write in our own words and do not copy sentences from sources.

Some publishers block automated access. When that happens, a species page cites the sources we could actually open (often Audubon, USFWS and similar), and links Cornell’s All About Birds as further reading rather than as a source. We do not list a source we did not consult.

Which species are included

The library starts with 30 widespread, well-known birds that people in many parts of the United States are likely to meet. More species and guides will be added in batches. A species is only published when its entry can be written and checked against sources.

How the Bird Finder filters work

Size

Based on the middle of the published total length range (bill tip to tail tip) in inches. Tiny: under 5. Small: 5 to under 8. Medium: 8 to under 14. Large: 14 to under 28. Very large: 28 or more. Birds near a boundary can feel like they belong to the next group, so use size together with other filters.

Predominant color

The main colors of a typical adult in the most common plumage, in order of how much of the bird they cover, up to three. Juveniles, females and seasonal plumage can differ. The identification section on each page covers those differences.

Habitat

The settings where the species is commonly found: forests and woodlands, wetlands and water edges, grasslands and fields, coastlines, cities and parks, backyards and feeders, and deserts and arid scrub. A bird can use several. A habitat tag means “commonly found,” not “only found.”

Region

We group the United States into six regions: Northeast, Southeast, Midwest, Southwest, Pacific West, and Alaska & Hawaii. A region is tagged only where the species regularly occurs, not where it appears rarely as a stray. Large regions contain many local differences. A bird tagged for the Southwest may be common in one state and absent from another.

Season

The seasons when the species can regularly be seen in that region. Dates are approximate, and spring and fall arrival or departure shifts with weather, latitude and elevation. Seasons are matched by region: choosing “Winter” in the Northeast shows birds that winter there.

Behavior

Typical feeding and movement habits, such as foraging on the ground or visiting feeders. These are tendencies, not rules.

Bill type

The overall shape of the bill, grouped into nine simple types. Bill shape is one of the most useful clues, and it tells you about diet.

How the Bird Finder ranks results

The Bird Finder compares your answers with each species. Birds that match every answer appear first. Close matches that differ on one or two answers appear next, with a note about which answer they miss. You can skip any question you are not sure about. Treat the results as candidates to check against the identification features on each species page, not as a final answer.

Similar species

Each species lists look-alikes and one or two practical differences. We list common confusions, not every possible one. Where a similar species has its own page, we link to it, and you can compare them side by side.

Conservation status

We report the IUCN Red List category and the date we checked it. We add US legal or population context only when a source supports it. Status can change. Please follow the link to the source for the latest.

Limits

• Birds vary by age, sex, season, wear, lighting and region.
• Migration timing changes from year to year.
• Some species cannot be separated by sight alone.
• Our entries can contain errors. If you spot one, email [email protected].

Photo credits