192 SOME COMMON LAND-BIRDS. 



into the pouches, or in letting it escape no one can say ; but it 

 seems not unlikely that it is the escaping air, rushing through 

 the vocal cords, that creates the sound, just as in penny- whis- 

 tles it is the escape of the air from the inflated rubber bag 

 that does the whistling. At least, if you watch the sooty 

 grouse, you will see that his bill is open when the noise is 

 made. On the other hand, when a horned owl hoots his bill is 

 closed. 



When he booms, the male grouse takes up his position on a 

 horizontal limb fifty feet or more from the ground, and, sitting 

 crosswise of his perch, crouches low, with wings drooping and 

 tail spread. The air sacks swell till they almost hide the 

 head, the red skin above the eye rises like a comb, the bill is 

 opened, the sacks contract and dilate and " poom-poom-poom- 

 um-poom" sounds the mellow love-call over the canon. Five 

 or six times in succession is the " poom-poom-poom-um-poom " 

 repeated before the bird stops to rest. 



The female is not visible. Perhaps, as in the case of 

 the ruffed grouse, her presence makes no difference in the 

 performance, which is for the male's own delight rather than 

 to attract a mate. While the male is booming, she inay be 

 dusting her feathers on some dry knoll, or she may be 

 hopping from branch to branch as she leisurely climbs to 

 the top of a tall fie tree, or she may be sitting cross- 

 wise of a limb looking out over the canon. She listens to the 

 mellow love-call of her mate, she basks in the warm spring 

 sun, and, while the spring lasts, before the summer cares of 

 the family have come, or the autumn fear of gunners in the 

 "open season," or the dripping winter rains have made the 

 woods a sodden swamp, she enjoys the greatest peace and 

 leisure of her life. 



If it were possible to linger in the oozy, mossy forests of 



