[l] BIRDS OF OREGON 



The bills also are variable, according to the feeding needs and feeding 

 habits of the species. Some striking examples of this variation may be 

 noted in the following forms: Swallows have an exceedingly weak bill 

 with an enormous gape that allows them to scoop up small insects while 

 in full flight. Nighthawks' bills are quite similar. Warblers are equipped 

 with slender, comparatively weak bills with which they pick small in- 

 sects from foliage and flowers. Sparrows, which are generally seed eaters, 

 possess powerful, cone-shaped beaks that are used in cracking hard seeds 

 and obtaining the meat from within. Hawks and owls are provided with 

 powerful hooked upper mandibles for tearing the flesh of their prey. 

 Ducks have wide, shovellike bills for scooping seeds, plant parts, and 

 small animal life out of the mud. Sometimes these bills are still further 

 adapted to this particular work by the presence of strainers and combs 

 that sift out and retain insects and other food when mud and water are 

 forced through them. The Shoveller, or Spoonbill, is a conspicuous ex- 

 ample of this type. Herons have long, sharp javelins with which they 

 stab their prey with lightninglike thrusts. Anyone who has watched a 

 Great Blue Heron impale an incautious fish will appreciate the power of 

 this equipment. The beak, which is long and needle sharp, is driven for- 

 ward by the long neck as if unleashed from a spring. Seldom does the 

 luckless fish, frog, or crustacean manage to move fast enough to escape 

 the deadly thrust. These examples indicate generally a wide adaptation 

 in birds' bills for the particular use to which they are put. Instances of 

 special adaptation could be cited almost indefinitely to further elaborate 

 this point. 



Feet and legs also are modified according to the needs of the different 

 species. Those of the swallows, swifts, and nighthawks are small and 

 weak, as these birds are constantly on the wing and do all their feeding 

 in the air. Obviously they do not need the strength in these organs that 

 is necessary in those of other species with different feeding habits. Most 

 of the sparrows, which feed on the ground, have rather stout legs and feet 

 equipped with powerful and elongated claws for use in scratching seeds 

 from the earth. Herons, ibises, and many of the shore birds have long 

 legs and elongated toes with which they can wade in the water and readily 

 walk in the soft mud. Rails have exceedingly long toes to enable them 

 to run about on the floating vegetation of the marshes. Ducks, cor- 

 morants, loons, and other water birds have webs between the toes, which 

 provide efficient paddles for swimming and diving. Coots have a curious 

 adaptation of this webbed-foot principle: instead of the webs extending 

 from toe to toe, as in most other swimming birds of Oregon, the webs are 

 flaps on each side of the toe that close as the foot is drawn forward and 

 open as it is pushed back. Hawks and owls, as a group, have strong feet 

 armed with powerful talons for striking and carrying their prey. In this 

 group the Osprey, which lives largely on fish, has a further curious 



