JoxES — Two All-Day Records in Xortherx Ohio. 69 



incite the birds to movement northward. Cloudy nights — 

 with the sky obscured — are unfavorable for bird movements 

 even if the weather be warm. Cold nights, even if the sky be 

 clear, do not induce much movement. Some birds migrate 

 on cold clear nights. For a large movement of the birds, as- 

 suming that the time of year has arrived for such movement, 

 at any given place which will be manifest on the next day, two 

 conditions seem to be necessary. First, the temperature must 

 be relatively high and the sky clear or nearly so for many 

 leagues south of the given place ; and second, to the north of 

 the place the sky must be overcast, or the temperature low, in 

 that place or immediately north of it. 



During the present season the weather conditions during 

 the last week in April and the first week in May were favor- 

 able for the northward movement of the smaller and later mi- 

 grating birds over most of the Mississippi Valley, and eastward, 

 at least as far as Lake Erie and southern Michigan. Most 

 of the second week in May was cold, with northerly winds pre- 

 vailing. Many birds had arrived during the favorable 

 weather, but remained in northern Ohio and adjacent regions 

 because of the storm and cold of the second week in May. 

 Then followed favorable weather south, but cloudiness over 

 Lake Erie nights up to May 16. The birds moved up to the 

 cloud barrier and remained there. On the 14th and loth the 

 country teemed with all sorts of birds except the divers and 

 ducks which had gone north earlier. Not only were species 

 unusually numerous, as the appended lists will prove, bur 

 individuals were enormously numerous. 



These two lists — Rev. W. F. Henninger, for Tiffin. Ohio, 

 Jllay 15th ; and the writer, for Oberlin, May 14th — are given 

 together, and the appended list of birds which were not seen but 

 were clearly present, for the purpose of indicating the status 

 of bird life during these two days as far as could be deter- 

 mined. It will be noticed that the 129 species found at Ober- 

 lin on the 14th establishes a new record for that place. How- 

 ever, the conditions which so profoundly influence so large a 

 proportion of the whole bird life of a region and not the size 



