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.
On the Galapagos islands, 13 species of finches can be classified into four subspecies. There are those that live in trees and eat fruits and bugs; those that also live in trees but are vegetarians; birds that live in trees, but look and act like warblers; and birds who spend much of their time hopping on the ground.