Jones — Migration at Oberlin, O. 199 



better to separate the records from this distinctively different 

 region from those of the definitely Oberlin reg-ion, but that 

 •could not be done without danger of serious mistakes. The 

 Cedar Point sand pit records are mainly those of water birds, 

 at least as they affect the appended tables. Some land birds 

 tarry there later in the spring than they have been found in 

 the Oberlin region. 



I have no hesitation in saying that the percentage of error 

 in these records must be small, because observations have 

 been carried on almost every day during the season of mi- 

 gration, and for weeks before any migration began and for 

 three weeks after it closed, and by a considerable body of 

 trained observers. Questionable records have been elimin- 

 ated. 



Since the Crow, Robin, Bluebird, ^leadowlark. Northern 

 Flicker, Bronzed Crackle, and Mourning Dove regularly re- 

 main all winter in small numbers, the exact arrival of the first 

 migrating individuals may not have been determined with 

 certainty in every instance, but the migration of these species 

 has been considered as begun with the advent of a considerable 

 number of individuals who were singing and evidently indi- 

 viduals which had not remained in the region all winter. 



The writer is well aware of the fact that averages based 

 upon few records are of questionable value. Nearly all of 

 the species which have been recorded as migrants are here 

 given for the sake of completeness, with no thought that av- 

 erages based on as few as nine records can be taken as true 

 averages. 



The median rather than the average date of arrival has been 

 used in these tables, because the median has proved the more 

 reliable in practice. Extremes in either earliest arrivals or 

 latest records of species which pass north to breed do not af- 

 fect the median as they do the average. 



The species are arranged according to their average date 

 of arrival as a matter of convenience for further studies of 

 the migrations rather than according to the systematic ar- 

 rans^ement of the A. O. U. Check-List. If this arrangement 



