443 
favorable for a large variety of avian life. The thrushes, catbirds 
and thrashers find nesting sites in the large number of thorn-bushes 
(Crategus); the woodpeckers and bluebirds, in holes in the rotting 
trees; the rails, bitterns and marsh wrens find protection among 
the cattails; and the crows and hawks find nesting locations high up 
in the tall trees. Many low bushes harbor the nests of the summer 
yellowbird, the goldfinch and the indigo‘bird. In fact the environ- 
ments obtainable here are suitable for a large majority of the nesting 
birds of northern [llinois. 
Food is everywhere abundant. The ponds and streams as well 
as the woods and fields teem with invertebrate life (mollusks, in- 
sects, crustaceans), thus affording endless supplies for the sustenance 
of nestlings. The preponderance of insect-eating birds in this 
region should be gratifying to the farmers, as during the spring these 
birds destroy vast numbers of injurious insects—a fact which is, 
unfortunately, not fully appreciated by the agriculturists. The 
hawks and owls are also very beneficial in destroying injurious 
rodents. In this connection the humble snake must not be over- 
looked, for it is equally valuable for this purpose. A number 
of birds were observed to feed on crawfish and also to feed their 
young on this crustacean. The stomachs of the young of the 
green heron and American bittern contained crawfish of large size, 
as did also the stomachs of the parent birds. The great blue heron, 
green heron, American bittern, and a single specimen of the fish- 
hawk were observed fishing in the East Branch of the Chicago River, 
evidently for crawfish, which are very abundant in this stream. 
Stomach pellets from the screech-owl were also observed to contain 
the remains of crawfish. 
It would seem eminently desirable that in a farming district, 
tracts of land similar to those recorded below should be preserved, 
that the birds may be allowed to nest unmolested; and the agricul- 
turist should be impressed with the value of these animals as de- 
stroyers of noxious insects, especially during the nesting season. 
GENERAL TOPOGRAPHY. 
If a map of the Chicago area as it appeared during Pleistocene 
time be examined, the following features will be noted in the north- 
ern part of the region, in the vicinity of Glencoe. 
