SEEN - SE European Bird Migration Network
Wing length
Fig. 1. Standard measurement of the wing-length

Wing-length: Maximum chord measurement
A ruler with a stop can be used.
Technique
The folded wing, parallel to the body axis, rests on a ruler (Fig. 1). The carpal joint of the wing is placed at the butt of the ruler (if the ruler has no stop, cut off at the zero-point, using the bulb of the second finger of the right hand). With the thumb of the same hand the wing is firmly but carefully pressed against. the ruler; at the same time the thumb of the left hand straightens the primaries to their maximum length by smoothing the lateral curvature and applying slight lateral pressure towards the bird's body at the level of the primary coverts. The third and fourth fingers of the left hand control folding and straightening of the wing.
Precision of measurement - l mm.
The most common mistakes in measurement -
Wing-length underestimated:
- the wing not fully pressed to the ruler,
- the primaries not fully straightened.
Wing–length overestimated:
- the carpal joint not taken fully to the butt of the ruler (this is much more probable when the ruler with the stop is used).
Created by Pronetix 2006