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A BI-MONTHLY MAGAZINE 

 DEVOTED TO THE STUDY AND PROTECTION OF BIRDS 



Official Organ of the Audubon Societies 



Vol. V September — October, 1903 No. 5 



The Mystery of the Black -billed Cuckoo 



BY GERALD H. THAYER 



INCREDULITY will doubtless be the predominant note in the 

 reception of the strange tale which I am about to unfold, yet living 

 evidence of its truth is yearly accessible to any one who has leisure 

 and inclination to seek it. I refer to the mid-summer, mid-night, mid- 

 sky gyrations of the Black-billed Cuckoo, as noted by my father and me 

 for three consecutive seasons in the southwestern corner of New Hamp- 

 shire. Here, in the country immediately surrounding Mt. Monadnock, 

 the Black-billed Cuckoo is a fairly common summer resident, while the 

 Yellow -billed occurs only as a rare autumn migrant. 



Several years before we discovered the nocturnal- flight phenomenon,, 

 we began to be puzzled by the extreme frequency of Cuckoo calls on 

 summer nights. These calls were far commoner than the same bird's 

 daytime noises; in fact, a week might pass without our seeing or hearing 

 any Cuckoos during the daylight hours, while they were nightly vociferous 

 around the house. They uttered both the cow -cow notes and the rolling 

 guttural call; but the guttural was much the commoner of the two, 

 except on dark, foggy nights, when the case was usually reversed. The 

 explanation of this difference was not immediately forthcoming, but was 

 suggested a summer or two later by our discovery that the birds were 

 almost invariably seated when they made the cow -cow note, and always 

 in flight when they made the rolling guttural. 



From this time onward I spent many evenings out-of-doors, on the 

 roads and in the woods and fields. I also slept out, on uncovered piazzas, 

 in an open tent, and occasionally on mother-earth on a high peak of Mt. 

 Monadnock. These evenings and wakeful minutes of the nights gave 

 me unique opportunities to study nocturnal bird -notes, and I had many 

 interesting experiences. Chief among these was the discovery, incredible 

 at first, but gradually forced upon my belief by steady accretion of the 



