GEOGRAPHIC DISTRIBUTION OF ANIMALS: OCEANIC ISLANDS 303 



these heavy-beaked drepanids the tongue has largely lost its tubular char- 

 acter. The extreme was represented by Psittirostra kona (Fig. 13.16). 

 which lived mostly on the hard nuts of the bastard sandalwood tree. Per- 

 kins wrote, "As the dried fruit ... is excessively hard, it is probable that 

 nothing short of the extremely powerful jaws . . . and their great mus- 

 cles would be able to crack them. In cracking them a sound is produced, 

 which is audible at some distance, and as it is incessant when the bird is 

 feeding, by far the most easy way to get sight of this, is to listen attentively 

 for the sound." 



Another extreme adaptation by the heavy-beaked group of drepanids is 

 represented by Pseudonestor (Fig. 13.17). Its beak suggests that of a 

 diminutive parrot and is used to expose the larvae, pupae, and immature 



FIG. 13.16. Beak of Psiftirosfra 

 kona. (After Rothschild; from Amo- 

 don, "Ecology and the evolution of 

 some Hawaiian birds," Evolution, 

 Vol. 1, 1947.) 



FIG. 13.17. Beak of Pseudonesfor. 

 (After Rothschild; from Amodon, 

 "Ecology and the evolution of some 

 Hawaiian birds," Evolution, Vol. 1, 

 1947.) 



Stages of wood-boring beetles. Perkins described the use of the beak as 

 follows: "The branch is gripped by the curved upper mandible and the 

 lower one opposed to it, and the burrow of the larva is exposed, either by 

 the act of closing the beak or by wrenching with it, the somewhat slender 

 tongue assisting in extracting the prey." The bird's equipment is powerful 

 enough to operate on hard wood. 



Our brief survey of this remarkable group of Hawaiian birds has in- 

 cluded mention of but a few of the thirty-nine drepanids found in the 

 islands. We have selected for mention the extremes of adaptation to dif- 

 ferent types of food. The species not mentioned possess beaks which fill 

 many of the seeming gaps between the conservative ancestral type (Fig. 

 13.11) and these extremes. As intimated above, such extremes of adapta- 



