True wingspan when recorded
When both birds have real wingspan data, their open-wing width can be compared directly at a shared scale.
Bird size & morphology database
Compare Bird Sizes
Compare birds using recorded wingspan, body length, body mass, wing length, tail, bill and other morphology measurements. The visual adapts to the data that actually exist for each pair.
10,664
birds searchable for comparison
56,855,116
possible bird pairings
Measured data
missing wingspans are never invented
Data foundation
BirdSize combines an AVONET morphology dataset covering roughly 11,000 living bird species with eBird-aligned taxonomy and additional published size measurements where available.
Start a comparison
Choose any two birds
Search by common or scientific name. Every bird in the catalog can be selected; the result automatically uses the measurements both birds actually share.
Popular birds Pick two here, or click a search box to browse without typing.
Keep loading birds to browse the catalog, or type a common or scientific name in either search box.
Adaptive comparison
One tool, different levels of measurement
The comparison changes with the available data instead of filling gaps with estimates.
Body length when span is missing
Recorded head-to-tail length can still drive a closed-wing visual comparison without turning wing length into wingspan.
Morphology beyond overall size
Wing length, tail, tarsus, bill dimensions, body mass and other shared measurements remain available for side-by-side comparison.