8 T. H’E-sA U8 D U BIO ON® BE Ul Lele aes 
DDT Sprays and Bird Mortality — II 
THE ARTICLE ON “Bird Mortality in Elmhurst” by Mrs. A. E. Montgomery 
in the September, 1956, Audubon Bulletin has led to inquiries from several 
Illinois communities and one government agency concerned with the dangers 
of spraying to wildlife. To provide additional information for towns or in- 
dividuals planning to take protective measures for their elm trees, the fol- 
lowing data has been compiled from a number of sources: 
There are many factors involved in the effects upon wildlife of large 
volume spraying with DDT and other chemical poisons. The Forest Preserve 
District of Cook County, 536 N. Harlem Ave., River Forest, Illinois, has 
published an informative free booklet, Nature Bulletin #411 of March 19, 
1955, entitled “Dutch Elm Disease.” Their “Annual Message for the Year 
1954” also contains useful data on this subject. The September, 1955, “Bul- 
letin of Popular Information” (price ten cents) published by the Morton 
Arboretum, Lisle, Illinois, discusses Dutch elm disease and recommends sub- 
stitute trees for street planting. An earlier, but extremely valuable publica- 
tion, is the free Circular 11 on “DDT: Its Effect on Fish and Wildlife” 
available from the U.S. Fish and Wildlife Service, Washington 25, D.C. 
The harm done to bird life by intensive spraying is emphasized by Dr. 
Ralph A. Yeatter, director of the I.A.S. and a member of the Illinois Natural 
Survey at Urbana. In a private communication he points out that: 
“The University of Illinois has been spraying the elms on the campus 
with DDT each year since 1949 in an attempt to prevent or control Dutch 
elm disease, and thus we are in a position to comment on the effects of DDT 
on robins. 
“From 1949 through 1952, the trees were sprayed twice each summer to 
kill leafhoppers, the insects chiefly responsible for spreading phloem necro- 
sis among elms. After 1952, the trees were given only one spray in summer 
(June), and one dormant spray, the latter to kill bark beetles, vectors of 
Dutch elm disease. Some elms on the campus have died, but the rate of loss 
is considerably lower than that for elms off the campus, where spraying has 
not been carried on or has been less thorough. 
“During the first and second summer of the University spraying, we re- 
ceived numerous reports of dead and sick robins on the campus. Dr. T. G. 
Scott and I searched a portion of the grounds on several occasions in 1950 
and each time dead robins were found. Reports received from men working 
on the grounds at the same time revealed that they had also found dead and 
sick robins. 
“The Natural History Survey ran analyses on a large number of these 
robins and found that DDT poisoning was the apparent cause of death in 
nearly all cases. It was believed that the birds accumulated fatal dosages by 
eating earthworms obtained from beneath the trees, for analyses showed 
that the earthworms contained relatively large amounts of DDT. 
“We have not heard many reports of dead birds on the campus for two 
or three years, but my own observation is that the population of robins there 
is now very low. Dr. S. C. Kendeigh also has the impression that robins are 
very scarce there. Dr. Scott has observed that there seem to be fewer earth- 
