1915] 
Cahn: Ecology of Wingra Springs Region 
151 
Vertical Zonation 
In regard to vertical zonation, little can at present be said, 
as there is not sufficient data at hand to warrant generalization. 
Two years’ data, however, seem to point to the probability 
that there is a fairly definite vertical zonation, but it will take 
considerably more observation to verify the statement. The 
notes at hand seem to show that the vertical zonation must be 
considered separately in at least two groups: (1) a group which 
starts on the ground and includes what we may for convenience 
call the “perching” birds — species that are dependent on shrubs 
and trees for their vertical distribution — and would include, 
for example, all of the common “song” birds; and (2) a group 
of species which we may call “aerial,” which would be comprised 
of the birds dependent upon their wings for vertical distribu- 
tion. In the latter group would fall the owls, hawks, gulls, 
terns, ducks, and geese. Just how the vertical distribution in 
this last group would work out is perhaps best shown in the 
case of the hawks and owls. The short-eared owl and the 
marsh hawk are low-flying species, seldom rising to any consider- 
able height above the ground. The great horned owl and the 
red-tailed or red-shouldered hawks are higher flyers respectively 
than the representatives of the preceding “zone.” In a similar 
manner, the geese are ordinarily higher flyers than the ducks. 
IX. ECOLOGICAL DISCUSSION OF THE SPECIES OF BIRDS 
REPRESENTED 
In the following paragraphs are summarized the data on the 
different species of birds found in the formation. For conve- 
nience the zones are referred to by number as follows: 
(1) Central lake zone. 
(2) Intermediate lake zone. 
(3) Shallow water zone. 
(4) Shore-line zone. 
(5) Spartina zone. 
(6) Cornus zone. 
(7) Sylvan zone. 
(a) Outer border zone. 
(b) Inner woods zone. 
(8) Open field zone. 
