30 The Wilson Bulletin — Xo. 98 



REMARKS ON THE MID-MAY CENSUS. 



W. DEWITT INIILLER AND CHARLES H. ROGERS. 



To US it seems that the vahie of this census, as of others, 

 such as " Bird-Lore's" Christmas one, lies more in the accuracy 

 of the count of individual birds, as a basis for comparison, 

 than in the total number of species noted. We strive for as 

 many species as possible consistent with as accurate as practic- 

 able an enumeration of individuals. Holding- such an opinion, 

 we venture to claim that our method, presently to be detailed, 

 is preferable to the methods of certain other of The Wilson 

 Bulletin's mid-May census takers. 



The frequent use of "common" in the Ohio lists means very 

 little and is practically worthless for comparison, especially 

 when it is used to the exclusion of all other terms, such as 

 "abundant," thus putting the Warbling Vireo and the Robin, 

 for instance, into the same class. Again, figures such as those 

 in Mr. Kohler's list last year, apparently estimates made after 

 returning from the field, we believe to be far from accurate. 

 For example, — on our 1916 "Big Day," Song Sparrows 

 seemed so ubiquitous that, had we not counted as we did, we 

 might easily have estimated them later at 250 (Mr. Kohler's 

 number for his census), but our figures show only 66. We 

 are, therefore, not convinced that Mr. Kohler and Mr. Tau- 

 benhaus, in somewhat less than ten hours, noted nearly four 

 times as many Song Sparrows as did we in fifteen or sixteen 

 hours of daylight, even supposing that species to be more 

 abundant in their region than in ours. 



Our big day is only a glorification of the kind of day each 

 of us spends on an average of over once a week all the year 

 around. On nearly every such occasion the individuals are 

 entered in the field notebook as often as seems necessary to 

 avoid forgetting any ; the species naturally appear on the pages 

 in the order of observation. This, however, is much too slow 

 for the Big Day, — the notebook would have to be opened 

 and perhaps several pages turned in looking for any species. 



