Every launched species starts as Common. As its coin grows it climbs one tier at a time: Uncommon, Rare, Very rare, then Legendary. At Legendary the plate is replaced by the bird's golden form, and its letters on the board turn yellow.
A tier, once reached, stays reached. Rarity on birdcall is a record of how far a sighting went, not a forecast of where it goes next.
Share of launched species at each tier, right now.
In flight means the species has been launched and its coin is still on its bonding curve on Stonks. The percentage is how much of the curve has been bought.
Seen means the coin has migrated off the curve. That is the moment the notebook stamps the species as seen, with the launcher's wallet beside it, and the club posts a new sighting.
Tiers and sightings are measured on-chain. birdcall shows them as percentages and tier names only; it never quotes prices.