Clubbing is an enlargement of the ends of the fingers and a downward sloping of the nails. Although it's not caused by chronic obstructive pulmonary disease (COPD), it can be a sign of coexisting lung cancer or other lung disorders in patients with COPD. Clubbing is sometimes called digital clubbing. It can affect the fingers and/or toes.
Relatives. Darwin's finches can be divided into groups based on beak type. There are three species of tree finch: the small tree finch, medium tree finch, and large tree finch. Tree finches have grasping beaks.
Darwin's finches share similar size, coloration, and habits. Their salient difference is in the size and shape of their beak. However, beak shapes can be very variable, and the size and shape in one individual can overlap into the range of another species.