Change in feather lengths as a result of their extension into the halo.

Measurements are taken along the curvature of the feather as far as possible. Only in some cases (marked with a *) can the feather be seen to reach the bone and thus its length measured. Other measurements are taken on the assumption that they do penetrate the halo and reach the bone (see text for details).测量操作应尽可能沿羽毛的曲率进行。仅在部分标记有星号（*）的案例中，可观测到羽毛抵达骨骼，因此可直接测定其长度。其余测量均基于该羽毛可穿透晕圈并抵达骨骼的假设，详细说明参见正文。