250 BULLETIN 10 2, UNITED STATES NATIONAL MUSEUM 



and directly to the nest. The position she assumed on the nest 

 varied, and one could never be sure whether she would be facing 

 toward the blind or away from it. The ruffed grouse, which builds 

 its nest at the base of a stump, a log, or tree, invariably faces away 

 from the side of the nest thus protected from the sneaking approach 

 of some prowling enemy. Prairie chickens, which nest in thick veg- 

 etation, will usually face toward the side that is opened up for pur- 

 poses of photography, a very desirable position for the photographer. 



Many of the prairie chickens studied exhibited extreme restless- 

 ness and made much more of a task of incubation than does the 

 ruffed grouse. One continuously shifted her position during the 

 course of the day; at other times she would pick aimlessly at the 

 nesting materials, and not infrequently she would reach far out of 

 the nest at some unsuspecting grasshopper or other insect that 

 chanced to alight on the tall grass. Certain females revealed a sen- 

 sitive, nervous temperament and quickly responded to any stimulus, 

 whether it was the caw of a crow or the hum of a distant tractor; 

 and even the shadow of a passing cloud was sometimes sufficient to 

 make her respond. When startled she would frequently elevate her 

 head to command a wider view of her surroundings. If she caught 

 sight of the source of her alarm, such as the passing of a dog, she 

 would retract her head, become perfectly motionless, and retain 

 a " frozen " position until the source of danger passed. If the 

 animal ventured too near she would fly off with a violent " whirrrr " 

 of her wings, which was sure to attract, if not startle, the intruder. 

 She would drop into the grass a short distance away, utter a sharp 

 distressing cry, and feign a wounded bird. After several repetitions 

 of the performance, until she had attracted the enemy away to a 

 safe distance from the nest, she would sail gracefully away, leav- 

 ing the bewildered creature behind. This behavior is common to 

 many birds, but the deception is remarkably well executed by the 

 prairie chicken. I have seldom seen a prairie chicken try these 

 tactics with a human being; apparently they have learned that it 

 is best in such cases to get out and away without the least delay. 

 That the leaving of the nest when flushed by a human being is a quick 

 performance is revealed by moving pictures. The usual speed is 16 

 frames per second in the ordinary moving pictures. It requires 

 only three or four frames of the picture to show the bird until she 

 is away from the scene. This means that it requires only three- 

 sixteenth to one-fourth of a second for the bird to leave the nest. 



As it is not possible in most cases definitely to establish the cause 

 of nest destruction, it is necessary to depend on circumstantial evi- 

 dence. In 1929, out of 12 nests studied in Wisconsin only three 

 reached the period of hatching. The adudt birds of two of the nests 



