Whipi'Oorwill Calls 89 



song is heard dni'iiig the night, but measurably diminishes 

 in frequency and intensity as the day begins to dawn." 

 (Life-histories of the Birds of Eastern I'ennsylvania, II, 

 90). Allison remarks more specifically along this line 

 concerning the whippoorwill in Mississippi wiien he says: 

 " The song generally commenced about seven o'clock on 

 clear nights ; and once T heard a whip-poor-will cry at five 

 in the morning. I heard none at all in bad weather." 

 (Auk, XXIV, 1907, 18). 



The surprising vocal ability of this more or less elusive 

 bird attracted the writer's attention while he was a mem- 

 ber of the staff at tlie University of Michigan Biological 

 Station during July and August of 1919. The Station is 

 located on Douglas Lake in Cheboj^gan county, Michigan, 

 about seventeen miles south of the Straits of Mackinac. 

 The immediate region is more or less heavily wooded and 

 few habitations are in close proximity to the Station. 

 Owing to the fact that favorable haunts for tJie whippoor- 

 will are abundant and conditions are suitable for rearing 

 tlie young, considerable numbers of the birds remained 

 continuously near our camp. Excellent opportunity was 

 thereby afforded for securing definite data on tlie calls. 



On several occasions counts were made of the number 

 of consecutive calls given by one bird as well as the number 

 of intervals and length of time occupied by each between 

 the series of consecutive calls. The results are brought 

 together in tabular form in this ])aper. In all cases count- 

 ing was discontinued when the interval was excessively 

 long or Avhen we no longer could be sure that we were lis- 

 tening to the individual bird with wliich our counts 

 started. 



In our experience, the calls were invariably more fre- 

 quent on warm, calm evenings. Scarcely anj^ calls were 

 given on windy nights. In the early part of July the birds 

 began calling about 9:00 p. m. and it was a noteworthy 

 fact that the calls started regularly within fifteen minutes 

 of this hour. As the evenings became longer and dusk 



