MICHIGAN ACADEMY OF SCIENCE. 
191 
Forest ( Sta . III). This station comprises a wooded flood-plain and slope 
stretching up to the top of the bluffs and extending back to the cultivated 
fields. The soil on the bluffs is sandy, allowing rapid percolation of the water 
instead of its running down the slope, thereby greatly diminishing the factor 
of denudation. The thin layer of humus is thus preserved except on the 
brink of the steeper bluffs where the weathering is so rapid as to prevent its 
formation. The process of erosion is dominant on the bluffs, while depo- 
sition is the controlling factor on the flood-plain. The erosion tends to 
reduce the bluffs to base level, and the process of deposition tends to increase 
the depth of the soil and establish an equilibrium between the bluffs and 
the flood-plain. The ashes, hickories, elms, and maples characteristic of 
low woodland clothe this portion, while the red and black oaks occur most 
plentifully on the high ground. Blue Jays, Red-headed Woodpeckers, Red- 
eyed Vireos and Wood Pewees, birds which are characteristic of wooded 
areas, are found here. 
Open Dry Meadow. ( Sta . IV.) These meadows consist of sandy soil 
overgrown with weeds and grasses. A cultivated field, raspberry batch and 
a sand pit are included. The dominant process is erosion which is constantly 
cutting down the higher portions. The thick beds of vegetation materially 
hinder this work. The characteristic birds are those of open dry meadows 
in general, namely, the Meadowlark, Field Sparrow, Prairie Horned Lark, 
Bobolink, Goldfinch and Vesper Sparrow. 
CONCLUSION. 
It is evident from the data given above that the birds in this region are 
quite restricted in their choice of habitat, and that the vegetation is the 
immediate factor which causes this limitation. The birds are to a consider- 
able extent dependent upon it at all seasons for their food and protection, 
while during the breeding season it determines the distribution of practically 
all of them, restricting many species to a very small area. But the vegeta- 
tion is dependent upon the physiographic conditions, and is modified by 
the processes working upon them, so that the distribution of the birds in a 
region at any particular time is also influenced by physiographic changes. 
It is therefore evident that the distribution of the birds in any given area is 
primarily determined by the geological formations, the physiographic changes 
taking place, and the resulting biota, i.e., the plant and animal societies 
characteristic of these conditions. 
ANNOTATED LIST. 
1. Podilymbus podiceps, Pied-billed Grebe. Station I. Rather common 
migrant; a few breed. 
2. Gavia imber, Loon. Station I. Rare migrant. 
3. Larus argentatus smithsonianus. American Herring Gull. Only seen 
flying over the river in spring and fall. 
4. Merganser americanus, American Merganser. Sta. I. Migrant; indi- 
viduals seen in spring. 
5. Nettion carolinensis, Green-winged Teal. Sta. I. Small flocks stop 
at the bayou in spring and fall to feed. 
6. Z.uerquedida discors, Blue-winged Teal. Sta. I. Small flocks found 
with Green-winged. 
7. Branta canadensis, Canada Goose. Seen flying over bayou in spring 
and fall. 
