GEOGRAPHIC DISTRIBUTION OF ANIMALS: OCEANIC ISLANDS 295 



tree for nectar. It also feeds on the soft pulp of this cactus and on a variety 

 of other food items. 



The vegetarian tree finch (Fig. 13.5) has a short, thick, somewhat 



'""^ 



FIG. 13.3. Beaks of three species of ground finches (Subgenus 

 Geospiza). (From Lack, Darwin's Finches, Cambridge University 

 Press, 1947, p. 57.) 



parrothke beak. Leaves, buds, blossoms, and fruits form its main items of 

 diet. 



The insectivorous tree finches (Fig. 13.6) have beaks much like the 

 beak of the vegetarian tree finch. They live chiefly on beetles and other 



FIG. 13.4. Beak of the cac- 

 tus ground finch [Geospiza 

 scandens). (From Lack, Dar- 

 win's Finches, Cambridge 

 University Press, 1947, p. 57.) 



FIG. 13.5. Beak of the veg- 

 etarian tree finch (Subgenus 

 Platyspiza). (From Lack, Dar- 

 win's Finches, Cambridge 

 University Press, 1947, p. 57.) 



insects, although they are not averse to young leaves, buds, and nectar in 

 season. 



One of the most remarkable of the finches is the woodpecker finch 

 mentioned previously. Its beak is stout and straight, similar to that of 

 tree finches, but longer (Fig. 13.7). Almost completely insectivorous, it 



