278 



SCIENCE 



[N. S. Vol. XXXVIII. No. 973 



SPECIAL ABTICLES 



PEELIMINAIIY NOTE ON BIRDS AS CARRIERS OF THE 

 CHESTNUT BLIGHT FUNGUS^ 



Statements have been made by various writ- 

 ers that birds play a part in the dissemination 

 of the chestnut blight fungus. Murrill" men- 

 tions the possible relation of birds to the dis- 

 ease and writes as follows : " Millions of mi- 

 nute summer spores emerge from day to day in 

 elongated reddish-brown masses to be dissemi- 

 nated by the wind and other agencies, such as 

 insects, birds, squirrels, etc.," also,' " every bird 

 and insect that rests upon an infected spot is 

 liable to carry the spores upon its feet or body 

 to other trees." A few years later Mickle- 

 borough* mentions birds as carriers of blight 

 spores. He says : " The minute spores are car- 

 ried by wind, on the feathers of birds and the 

 fur of squirrels." Still later Metcalf and Col- 

 lins' say, " there is strong evidence that the 

 spores are spread extensively by birds, espe- 

 cially woodpeckers." Various writers have em- 

 phasized the fact that woodpeckers frequent 

 chestnut trees in search of insects. Fulton' 

 states in a report on field work done at Orbi- 

 sonia. Pa., by E. C. "Walton that " woodpecker 

 work was noted in about one tenth of the old- 

 est lesions," but offers no conjecture as to the 

 part played by birds, in the dissemination of 

 the blight. 



Stewart' says, "undoubtedly the spores are 

 carried long distances by birds, especially 

 woodpeckers, which visit the diseased trees, 

 seeking borers, in the tunnels of which most 

 ^Investigations conducted in cooperation with 

 the Pennsylvania Chestnut Tree Blight Commis- 

 sion. 



^Murrill, W. A., "A Serious Chestnut Disease," 

 Jour. N. T. Botanical Garden, 7: 146, 1906. 

 »Z6id., 152. 



* Mickleborough, J., "A Eeport on the Chestnut 

 Tree Blight," Pa. Dept. of Forestry, unnumbered 

 buUetin, p. 11, 1909. 



"Metcalf, Haven B., and Collins, J. Franklin, 

 "The Control of the Chestnut Bark Disease," U. 

 S. Dept. Agr., Farmers' Bui. No. 467: 9, 1911. 



'Fulton, H. R., "Recent Notes on the Chestnut 

 Bark Disease," Harrisburg Conf. Eep., p. 56, 

 1912. 



'Stewart, F. C, "Can the Chestnut Bark Dis- 

 ease be Controlled?" Harrisburg Conf. Eep., p. 43, 

 1912. 



of the infections occur." This statement is 

 based on the report of Metcalf and Collins 

 previously referred to, and is discredited by 

 Fisher,' who brings out the point that this and 

 similar statements are not based on positive 

 evidence. There are numerous popular 

 articles which also accuse birds of being in- 

 strumental in the spread of the blight, but 

 these as well as the statements already quoted 

 are based entirely on circumstantial evidence. 

 The first serious attempt to determine 

 whether birds actually do carry the spores of 

 the blight fungus were made by the field pathol- 

 ogists of the Pennsylvania Commission during 

 the summer of 1912.° They report the testing 

 of twenty birds as follows: eight downy wood- 

 peckers, three creepers (kind not mentioned), 

 two hairy woodpeckers, four flickers, and three 

 blue jays, all with negative results. No sug- 

 gestions will be made at present to account for 

 their negative results, but our positive results 

 will be presented. 



During the past spring the writers have de- 

 voted considerable time to the testing of birds 

 as carriers of the blight fungus. The first 

 accurate analyses were made in February and 

 the work was continued until about the middle 

 of May. Thirty -six birds belonging to nine 

 different species have been examined." The 

 birds were shot in the field and placed at once 

 in sterile paper sacks for transport to the com- 

 mission laboratory at the University of Penn- 

 sylvania, where the quantitative analyses were 

 completed. Most of the birds tested were shot 

 at either West Chester, or at Martic Forge, or 

 in the vicinity of these places, since we wished 

 to use the rainfall records which we were 

 keeping at those stations. The method of 

 making an analysis was as follows : A flask 

 containing 100 c.c. of sterile water was emp- 

 tied into a sterile moist chamber, and the bird 

 'Fisher, A. K., Harrisburg Conf. Eep., p. 103, 

 1912. 



"Anderson, P. J., Elza, W. H., and Babcoek, 

 D. C, "Field Studies on the Dissemination and 

 Growth of the Chestnut Blight Fungus," Bulletin 

 Pennsylvania Chestnut Tree Blight Commission 3 : 

 (in press), 1913. 



1° The birds used in this work were shot by Mr. 

 C. E. Taylor, who was formerly employed by the 

 Pennsylvania Chestnut Tree Blight Coromission. 



