^3 



3. Wheu it becomes common. 



4. When the bulk departs . 



5. When the last iudmdual is seen. 



In addition to the above data, which all observers are requested to fur- 

 nish, the Department particularly desires exact records of every increase 

 and decrease in the numbers of a given species over a given area ; for it is 

 only by the knowledge of the daily fluctatious of the same species in the 

 same place that the progress and movements of a "flight," or "bird- 

 wave," can be traced. Such data can be contributed by experienced ob- 

 servers only, and in their procurement much time must be spent in the 

 field. During the progress of the migratory movement the observer 

 should go over the same ground day after day, and, if possible, both early 

 in the morning and late in the afternoon. He should visit woodlands, 

 thickets of dense undergrowth, and open fields ; and if possible, both 

 swamp and upland should fall under his daily scrutiny. 



The above 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 men- 

 tioned the bodily condition of the bird (whether fat or lean), the molut, 

 and the periods of song. The time of mating, when observed, should al- 

 ways be recorded. 



(h) Meteorological Phenomena. 



Information is desired upon : 



1. The direction and force of the wind. 



2. The direction, character, and duration of storms. 



8. 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 Department 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. 



5. The dates at which various insects are first seen. 



6. The dates of the flowering of various plants. 



7. The dates of the leafing and the falling of the leaves of various trees 



and shrubs. 



8. The dates of the breaking up and disappearance of ice in rivers and 

 lakes in spring, and of the freezing over of the same in the fall. 



Carl Fritz Henning, 

 Chief of Migration Dep't. 922 Eighth St. Boone, Iowa. 



