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.
Cracker Beaks. Birds that eat primarily nuts and seeds have short, conical beaks that are widest at the base. These are made to crack open shells and extract the inner nut or seed meat. Sparrows, finches, cardinals, bluejays, grosbeaks and juncos are examples of birds with cracker-style beaks.