Wing chord (biology)

Wing chord mesure on a Red-billed Chough chick during ringing.

Wing chord is an anatomical measurement of a bird's wing. The measurement is taken with the wing bent at a 90 degree angle, from the most prominent point of the wrist joint to the most prominent point of the longest primary feather. It is often taken as a standard measurement of the proportions of a bird and used to differentiate between species and subspecies.