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though still an undergraduate student in the University of Illi- 

 nois, has had several years' experience as a collector and ob- 

 server of birds — were sent into the field under instructions to 

 travei'se the state in various directions, traveling always in 

 straight lines and always thirty yards apart, and noting and 

 recording the species, numbers, and exact situation of all birds 

 flushed by them on a strip fifty yards in width, including also 

 those crossing this strip within one hundred yards to their 

 front. No attention is paid by them, for this purpose, to any 

 other birds. 



As they are able to recognize with accuracy all species of 

 Illinois birds at sight, and most of them by song, their move- 

 ment is like that of a gigantic sweep-net 150 feet wide and 300 

 feet deep, so drawn across the country day by day as to capture 

 every bird which comes in its way; with this difference, that 

 the birds are not actually caught or even inconvenienced, and 

 that nothing can escape the meshes of their well-trained ob- 

 servation. 



One of these observers, Mr. H. A. Ray, also a University 

 student, is primarily responsible for the record of distances and 

 kinds of surface over which they travel, carrying for this pur- 

 pose a pedometer whose action has been carefully tested and 

 repeatedly checked, and a mechanical tally or "lumber-coun- 

 ter" — both used to make a record of the number of paces trav- 

 eled over each crop or other kind of surface vegetation. 



The reports of their travel made to me by Mr. Gross con- 

 tain every needful detail as to date and time of day; to precise 

 location of their line of march; to temperature, wind, and oth- 

 er features of the weather; to distances traveled in succession 

 over each field or other distinguishal)le area; to vegetation, 

 wild or cultivated, on each tract; and to the species and num- 

 bers of birds identified on each area and in each kind of crop. 



General Results of Observations. 



The present paper is a discussion of the product of one of 

 their earlier trips, made from August 28 to October 17, 1906, 

 across the state from east to west, from the Indiana line be- 



