4 Tue Witson Burrrtin, No. 74. 
dwelling places of man, not finding sufficient food there, flock 
in groups of 25 to 150 and invade the wheat and clover fields. 
It was noticed repeatedly that whenever English sparrows in- 
vaded crop lands it was virtually always in good sized flocks. 
Aside from food there are other factors in the environment 
which favor an abundant bird population. The large number 
of protected nesting sites is an important factor in this region, 
which has seemed to increase the number of individuals with- 
in a given species. The general climate is favorable and the 
duration of the warm weather is such that two or even three 
broods may be raised each year. 
Altho there would seem to be plenty of sustenance for birds 
of prey, their general absence was conspicuous. This is prob- 
ably due to the many gunners in this region, both in and out 
of season, but particularly during the early spring. By the 
end of the hunting season the hawks that would have nested 
here have found nesting sites elsewhere and their occurrence 
in this vicinity seems to be merely accidental. 
One might easily judge from the forgoing description of the 
region that, containing as many varied environments as it 
does, the bird population would be conspicuous both for num- 
ber of species and for abundance of individuals. The region 
is indeed well populated with many individuals of a compar- 
ativly few species, but the total number of species is not so 
large as might be expected, since the region lies a little ways 
north of the northern limit of the southern ayifauna and quite 
a ways south of the southern limits of a large number of 
northern species. [lowever, the bird life is rich in comparison 
with the rest of central Illinois. 
In this paper the plant associations form the basis for di- 
vision. By such a method a much better idea of the relation- 
ships of the avifauna is brought out than an annotated list 
of the species, tho it is recognized that this analytical method 
does not necessarily yield the ecological avian associations. 
They are the product of a more thoro synthetic insight into 
avain relationships. It is highly probable that avian associa- 
tions will be correlated with plant associations or groups of 
