62 Bericht über das permanente internationale ornithologische Comite. 



to those in Spanish America, are scattered over the whole 

 country, extending in the East from Sombrero Key, Florida, 

 to New-Foundland; and in the West from Arizona and 

 Southern California to British Columbia. They are most 

 numerous in New-England, the Atlantic district, the Missis- 

 sippi Valley and Nova Scotia. 



Comparatively few of the observers are ornithologists, 

 or even bird-coUectors, the great majority being intelligent 

 Farmers, tradesmen, and light-keepers. 



The material now in band is of great value, and is 

 so voluminous that the Committee cannot properly arrange, 

 systematize, and publish it , without Government aid. Its 

 value does not consist wholly in its scientific interest, for it 

 has direct bearings upon many of the problems with which 

 the practical agriculturist is concerned. 



Birds are known to migrate with great regularity. 

 Still, the exact date of the arrival of a given species 

 at a given locality varies somewhat from year to year, 

 according to the advancement of the season, the State 

 of the weather, and other causes not yet perfectly under- 

 stood. The work of the Committee, therefore, is not limited 

 to the accumulation of records of the tiraes of arrival and 

 departure of the different species, but embraces the collec- 

 tion of all data that may aid in determining the causes 

 which influence the progress of migration from season to 

 season. For example, severe storms, gales of wind, and pro- 

 tracted periods of unusually high or low temperature (for 

 the locality and time of year) are among the atmospheric 

 conditions that are known to exert marked effects upon 

 the movements of birds. The opening of the leaves and the 

 flowering of certain plants, with the correlative appearance 

 of a multitude of insects, are also among the factors that 

 have to do with the abundance of many species, Hence the 

 careful registration of certain meteorological phenomena, 

 and of the State of advancing Vegetation from day to day, 

 constitutes a prominent item in the record books of the 

 observer. 



