31* 



AVES. 



general form produces infinite variety in the 

 application of the force. 



A compressed beak with sharp edges and a 

 hooked extremity characterizes both the Birds 

 of Prey properly so called, which destroy the 

 smaller quadrupeds and birds (Jig. 112); and 

 also the carnivorous species of a different order 

 that live on fish, as the Petrels (Jig. 142), Al- 



Fig. 142. 



of being as deep as it is long), and the Skimmer 

 (Rfiyncops), in which the still more singular 

 structure obtains of an inequality in the length 

 of the two mandibles, the upper one being con- 

 siderably the shortest ; so that this bird can 

 only get its food, which consists of floating 

 marine animals, by pushing them before it 

 as it skims along the surface of the water. 



Fig. 144. 



Bill of the Petrel. 



batrosses, Frigate-bird, and Tropic-bird. But 

 in the Raptores it is comparatively shorter and 

 stronger, and in some genera a tooth-like pro- 

 cess on either side adds considerably to its 

 destructive powers : hence the Falcons which 

 possess this armature are reckoned the more 

 ' noble ' and courageous Birds of Prey. 



The Insessorial Shrikes which have their bill 

 similarly armed do not yield in courage to the 

 Hawks, notwithstanding their small size, and 

 the comparative feebleness of their wings and 

 feet: (Jig. I \ 5.) 



As the bill becomes narrower and straighter, 

 it characterizes birds of a voracious habit, but 

 less daring in their attacks on other birds, 

 such as the Crows, Magpies, &c., (fg. 116) ; 

 and the compressed knife-shaped bill is asso- 

 ciated -with similar habits in the Water-birds, 

 as the Gulls, Grebes, Dabchicks, &c. 



Another kind of strong 

 and trenchant bill, which 

 more elongated and 



Bill of the Skimmer. 



Lastly, there are trenchant bills which 

 are depressed or flattened horizontally ; they 

 serve to seize fishes and reptiles, and other 

 large objects; the Boat-bill (Cancroma) 

 exhibits a bill of this kind (fig. 145), which 

 is also ser- Fig. 145. 



rated at the 

 edges. Some 

 speciesofFly- 

 catcher and 

 Tody have 

 this form of 

 beak on a 

 small scale . BiU f the Boat-bill. 



Of the blunt-edged bills we may first notice 

 those which are flattened horizontally. When 

 a bill of this description is long and strong, as 

 in the Pelecan (Jig. 146), it selves to seize a 

 large but feebly resisting prey, as fishes. 



Fig. 146. 



is 



without a hook, serves to 

 cut and break, but not 

 to tear : this form of bill 

 characterizes the Waders 

 which frequent the water 

 and prey upon animals 

 that make resistance in 

 that element, as reptiles, 

 fishes, &c. In the He- 

 rons and Bitterns the. 

 bill is straight; in the Ib^ it is curved down- 

 wards (Jig. 123); in the Jabiru (f.g. 143) it 

 is curved in the contrary direction. 



Bill of the Pelecan. 



When it is long and weak, as in the Spoon- 

 bill, which derives its name from the dilated 

 extremity of the mandibles, it is only available 

 to seize amid sand, mud, or water, very small 

 Crustaceans, Mollusks, &c. (Jig. 147.) 



Fig. 147. 



BUI of the Jabiru. 



Some trenchant or sharp-edged bills are 

 so compressed as to resemble the blade of 

 a knife, and can only serve to seize small ob- 

 jects, which are immediately swallowed : such 

 is the form of the beak in the Auks, Puffins, 

 Coulterneb, (where it has the further peculiarity 



Bill of the Spoonbill. 



The more or less flattened bills of Ducks, the 

 more conical ones of Geese and Swans, and 

 that of the Flamingo,* of which the extremities 



* It is singular that it should ever have been 

 supposed that the upper mandible was alone move- 

 able, and the lower mandible perfectly immoveable, 

 in the Flamingo, since precisely the contrary is the 



