620 The A ninial Kingdom 



for spearing grubs. The hummingbird has a long siphoning tongue 

 for getting nectar from flowers. 



Like the bills, the wings of birds vary with the habits. Those birds 

 that fly long distances and remain in the air for extended periods of 

 time have broad, strong wings ; those birds that only fly for short dis- 

 tances have short, rounded wings. Some birds that are adjusted for an 

 aquatic life, such as the penguins, have their wings modified as flippers 

 that propel the bird rapidly in water. Among running birds such as 

 the ostrich, the wings are reduced and no longer serve for flight. 



As the bills are adapted to the food habits of birds so the legs and 

 feet likewise are modified to suit the various ways of life. Most birds 

 have four toes, three in front and one behind. The small perching birds 

 have small feet with slender toes which function like clamps. When 

 the bird alights, the toes automatically lock in place on the limb and do 

 not release until the leg is straightened for flight. The sleeping bird 

 thus is in no danger of falling from its precarious perch. Swimming 

 birds such as the ducks have webbed feet for rapid propulsion through 

 the water. Wading birds have long slender legs and toes for distribut- 

 ing their weight over the soft substrate. Birds of prey such as hawks 

 and eagles have heavy toes with talons for tearing and grasping prey. 

 Most ground-dwelling birds (quail, etc.) have heavy feet for scratch- 

 ing on the ground. The woodpeckers which climb up branches have 

 two toes in front and two in back to aid them. Even more highly modi- 

 fied is the foot of the ostrich in which the number of toes is reduced to 

 only two. 



Habit Variations. — Structurally the birds are a very homogeneous 

 group, but certainly this homogeneity does not extend to their habits. 

 And nowhere is the variation of habits more evident than in their 

 mating and reproductive behavior. With some birds, the courting be- 

 havior consists only of some noisy singing from a perch ; with others, it 

 results in elaborate displays. Many examples of this behavior can be 

 cited. The male woodcock when courting the female whirls upward 

 to a height of about 50 feet, then suddenly circles and descends ; when 

 he reaches the ground, he struts about in front of his mate. All the 

 grouse have elaborate courtship patterns which involve gregarious dis- 

 plays. The eastern prairie chicken or prairie grouse can often be 

 heard for long distances as they boom on their spring mating grounds. 

 Here the males strut about, inflate their orange air sacs, and droop 

 their wings and spread their tails. Now and then males approach each 



