^°19^8^^] Wood, The Spring Migration, 1907, at Ann Arbor, Mich. 13 



Conclusion. 



By comparing these dates of arrival with my table of migration 

 for 25 years (Eighth Report, Michigan Academy of Science, 1906, 

 pp. 151-157), I find they correspond very closely with the average 

 dates of arrival as given there, showing that this year the later 

 migrants arrived in this locality at about the same date, and further 

 that very few are later than usual, notwithstanding the cold and 

 the fact that all vegetation was at least two Aveeks later than usual. 

 This favors the belief that these birds are not governed exactly in 

 their northward migration by weather or food conditions, but that 

 while they may start out on their migration only under favorable 

 conditions, they often migrate into regions of unfavorable conditions 

 before being checked. Thus the species that reached this locality 

 were in fine condition, but as the conditions here as well as to the 

 northward were unfavorable, many individuals remained here an 

 unusually long time. This was strikingly illustrated by the fact 

 that many of those that migrate the farthest north were the last 

 to leave this locality. I found no evidence of mortality here, due 

 to weather or food conditions, but Miss Harriet Wright of Saginaw, 

 Mich., wrote me that on the morning of May 27 (following a severe 

 night with snow and ice), she picked up numbers of dead warblers 

 of the following species: Tennessee, Canadian, Chestnut-sided, 

 ^Magnolia, Blackburnian, and Black-throated Green Warblers. 



Furthermore, as proof that birds of many species do migrate far 

 ahead of safe weather and food conditions, Prof. W. H. Munson 

 of the State Normal School, Winona, Minnesota, has given me the 

 following statement: "The weather was cold in May, and the 

 vegetation very backward, insect life was scarce and the migrants 

 (which came a little later than usual) had hard work to find suffi- 

 cient food. This fact combined with the severe cold and storms 

 caused the death of hundreds of birds of many different species. 

 The greatest mortality seemed to be among the Flycatchers of 

 which the Least Flycatcher seemed to suffer the most. A boy 

 brought to me a peck basket nearly full of birds, consisting prin- 

 cipally of this species, which he had picked up along the bluff 

 where the birds went for protection from the storms. Large 

 numbers of Black-and-White W^arblers were found dead, and the 



