18S4.] Bird Migration. y CJ 



In many species the mules arrive in advance of the females, 

 hence it is important to note the sex of the first comers, and the 

 date at which the opposite sex is first seen. 



In recording arrivals and tlepartures it is highly important to 

 distingnish between the movements of the great bulk of the spe- 

 cies and those of the forerunners or advance guard. For this 

 purpose two dates should be recorded for the incoming, and two 

 for the outgoing of every non-resident species, as follows : — 



1. The first appearance of the species (F). 



2. The arrival of the bulk (BA). 



3. The departure of the bulk (BD). 



4. The last individual seen (L). 



In addition to the above, which may be regarded as essential 

 data^ there are many other noteworthy details that bear more or 

 less directly upon the complicated problems involved in the study 

 of migration. Among such may be mentioned the bodily condi- 

 tion of the bird (whether fat or lean), the moult, and the periods 

 of song. The time of mating, when obsen-ed, should always 

 be recorded. 



((5) Meteorological Phenomena. 



Extended meteorological data are not required, though the 

 observer would derive material assistance from a systematic 

 weather record. The Committee desires information upon : — 



1. The direction and force of the wind. 



2. The direction, character and duration of storms. 



3. The general conditions of the atmosphere, including 

 rainfall. 



4. The succession of marked warm and cold waves, including 

 a record of all sudden changes of temperature. 



(c) Contemporary and Correlative Phenomena. 



The Committee desires that the data under this head be as full 

 and complete as possible, and requests exact information upon : 



1. The date at which the first toad is seen. 



2. The date at which the first frog is heard. 



3. The date at which the first tree-toad or '•'•peeper" is heard. 



4. The dates at which certain mammals and reptiles enter 

 upon and emerge from the state of hibernation. 



