Avian Humphrey-Parkes (H-P) plumage terminology and molt-limit ageing engine. Decode annual feather replacement cycles between juvenile, alternate, and basic plumages.

MOLT EXTENT

First Generation

SEASON / TIMING

Fledging (June–July)

AGE BAND CODE

HY (Hatch Year)

The Bander's "Molt Limit" Technique: In a bird's first autumn, the preformative molt replaces body feathers and inner wing coverts, but retains the juvenile primary coverts. Through binoculars or banding grip, look for the sharp contrast line between fresh, dark glossy inner coverts and faded, brownish, abraded outer juvenile coverts to prove the bird is in its first year of life!

🪶 Bird Molt Cycle & Ageing Lab