114 
FIFTEENTH REPORT. 
NOTES ON MORTALITY OF YOUNG OF WILD BIRDS UNDER 
NATURAL NESTING CONDITIONS AND UNDER 
ARTIFICIAL OR PROTECTED STATES. 
BY JEFFERSON BUTLER, PRESIDENT MICHIGAN AUDUBON SOCIETY. 
For a number of years I have been interested in the study of bird 
life. This study has been confined almost wholly to the living bird 
mainly because of the strong appeal of these creatures to the nature 
lover. Also because the dead bird had had considerable attention and 
the living had, it seemed to me, been in many phases of its life neg- 
lected. The taking of birds for records in geographical distribution 
has probably occupied the attention of more ornithologists than any 
otiier branch of bird study. Of course much time has been necessarily 
given to the structure in order to properly classify our birds as well 
as to general habits, nidification and means of identification. 
The study of migration and economic ornithology has but lately re- 
ceived attention and the life history of birds is of comparatively recent 
origin. The question of the balance in nature in regard to bird life is 
due to receive much greater attention than in the past. After 15 years 
of effort in identifying our common birds through the opera glass I 
turned my attention to the question of the bird’s struggle with nature. 
I endeavored to learn the experience of ornithologists in regard to the 
loss of eggs and young of our wild birds without obtaining more than 
very meagre results, but with sufficient to lead me to believe that the 
loss of bird life was heavy. It may be possible that we shall learn 
after the publication of this article that some other person has done 
this work with such thoroughness as to give us reliable statistics. Re- 
cently I wrote Mr. W. L. McAtee, Assistant Biologist of the U. S. 
Biological Survey, and received the following letter: 
“I regret to inform you that none of our publications contain any 
particular information about the percentage of destruction of the eggs 
or nests of birds. While studying at the University of Indiana, Bloom- 
ington, I kept some statistics on this point one year. I found in all 22 
nests in a certain orchard, and 18 of them were destroyed by various 
agencies, principally cats aud boys. In few instances I imagine, is 
the destruction less than 50 per cent and often it is more. I enclose some 
extracts from a paper by Joseph Grinnell bearing on this subject.” 
Mr. Grinnell’s observation was made in the San Bernardino Moun- 
tains, Cal. He estimated that there was about half a million birds in 
an area of 304 square miles. After taking all the accidents and fatali- 
ties during the nesting season into account he places the number of 
young at half a million. He recalls the fact that though some species 
increase in favorable years others decrease and that the population re- 
mains constant. This he says would mean the destruction of half a 
million birds for the year after the young are matured and would mean, 
I presume the loss through accidents in migration and death through 
