ala 
richer fallow lands of the prairie, and in spite of persecution are more 
abundant there. Voles are sometimes abundant where the dense 
shelter of grass they require is present, and shrews are often taken. 
In the northern part of the county, where woodchucks are 
found, their burrows are most common in the pasture-lands. Prob- 
ably this would not be the case, however, if the farmers on the mo- 
raines were accustomed to keep their fields in clover for several 
successive seasons. 
The other mammals found in the pasture-lands are transient 
visitors rather than permanent residents. The pastures are favorite 
hunting-grounds of the skunk, and it occasionally digs its burrow 
in the edge of alot. In the vicinity of woodland, rail fences, or other 
continuous shelter, chipmunks may occasionally venture into the 
fields, and rabbits visit them and, rarely, make their nests in a 
ticket there. 
The fact that these permanent pastures are in general much 
poorer in smaller mammalian life than the moraines of the prairie 
is not evident at first, but careful examination will make it apparent. 
The reason is plain. On the moraine belts there is abundant food 
and a comparative scarcity of larger Carnivora and birds of prey. 
The permanent pastures furnish less food, and are for the most part 
in the vicinity of woodlands that are the habitat of skunks, weasels, 
coons, and foxes, and afford nesting places for hawks and owls. 
It is another illustration of how httle the direct persecution of man 
affects these smaller animals compared with the injury inflicted on 
them by their natural enemies. 
FLOOD-PLAINS. 
The portions of the river valleys subject to overflow for a longer 
or shorter period each year, though forming but a small part of the 
county, furnish a habitat of peculiar interest. For the most part 
these flooded tracts are from four to six feet above the summer level 
of the water, though unusual floods may rise much higher than that. 
For example, the high-water mark reached by the Sangamon in the 
spring of 1908, was fourteen feet above the water-level in Septem- 
ber. These bottoms are usually sparingly wooded. The streams 
are often fringed with willows, the lower bottoms are treeless or bear 
a scattered growth of sycamore, elm, ash, and button-bush, while 
along the edge of the flood-plain, oak, water-maple, honey-locust, 
