n 
3. When it becomes common. 
4. When the bulk departs. 
5. When the last individual is seen. 
In addition to the above data, which observers are requested to fur¬ 
nish, the Department particularly desires exact recorfl.s 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 fluctations 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 'iregarded 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. 
(/>) Meteorological Phenomena. 
Information is desired 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 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, 
922 Eighth St. Boone, Iowa. 
Chief of Migration Dep’t. 
