64 ANIMAL COMPETITORS 
there are many inexpensive methods for pre- 
venting this increase. The destruction of rank 
grasses and weeds along fences and ditches, 
and particularly, in the West, the pasturing off 
of the last growth of alfalfa in fall, thus ex- 
posing the mice to the sight of predaceous en- 
emies, are important. Winter-burning of dry 
vegetation on wild hay lands, on strips border- 
ing fields, and on swampy or otherwise waste 
areas in and about cultivated fields, will aid 
materially in controlling them. The survivors 
may invade cultivated fields, but there they can 
be more readily poisoned. Flooding the fields 
in cold winter weather, when the mice quickly 
perish from exposure, is an effective method 
in irrigated lands. Plows turn out the bur- 
rows and nests of practically all the mice pres- 
ent and render them easy victims for dogs, 
which when trained to kill mice can not be too 
highly recommended as effective and inexpen- 
sive aids in controlling the pests. That hawks, 
owls, gulls, crows, ravens, and herons among 
birds, and skunks, weasels, foxes, and badgers 
among mammals, are persistent enemies of 
field-mice and other rodent pests has been often 
