INTRODUCTION. xvu 



from the effects peculiar to its insular habitat, retains 

 a plumage of the same colors throughout the year. This 

 provision of nature for the other species, may be 

 to give an additional security to the birds when the 

 whole country of their northern homes is covered by 

 snow% and so assimilate them to the surrounding white- 

 ness, that their presence can only be perceived with 

 great difficulty or by merest chance. 



Many Grouse possess a peculiar structure, rarely found 

 in any other species, in the air sac on the side of the 

 neck which is capable of being inflated, and then resem- 

 bles somewhat an orange attached to the neck. By ex- 

 hausting the air, which can be accomplished at the will 

 of the bird, a booming sound is produced that may be 

 heard at a great distance. This performance usually 

 takes place at the breeding season, and is one of the 

 male's allurements to secure the attention and probable 

 fleeting attachment of the females. At all other seasons 

 this sac shrivels up and is mostly concealed under the 

 feathers. 



One species of another group — Shore Birds — possesses 

 a similar sac, but differently disposed and of great extent, 

 which is also exhibited to advantage during the breed- 

 ing season. This is the Pectoral Sandpiper, a descrip- 

 tion of whose performance on the tundras of the far 

 north I have given in my work on the Lim\co\(£. 



North America has been most favored among the 

 countries of the earth in the great variety and number 

 of her gallinaceous birds, many of the species being 

 equal to any found in other lands and some surpassing 

 all others known, in size, magnificent appearance, and in 

 their value, commercially and otherwise, to the human 

 race. They are a precious heritage, to be guarded care- 

 fully and used judiciously if we are wise and far-seeing, 



