52 AN ECONOMIC STUD"? OF FIELD MTCE. 
husking time a^ they hover in the air or sit on a fence post or top o: 
a hedge, ready to pounce upon every mouse that e<eapes from corn 
shocks as they are torn down or moved. 
The smaller shrikes {Lanim ludovicianus and subspecie-) als< 
somewhat resemble mocking birds in color. They are summer resi- 
dents of many parts of the United State-. As insects are abundant 
during the greater part of their stay, they are insectivorous to a 
greater extent than the northern shrike. Stomach examinations 
prove that mice form 16 per cent of the food for the entire year, hut 
the birds are less able than the larger species to cope successfnlh 
with adult meadow mice, yet they undoubtedly destroy a good man; 
voles, and several have been identified in their food; but smallei 
mice are more frequently caught. 
Although shrikes destroy a few useful birds, they more than com- 
pensate for this by their destruction of small rodents and insects, anJ 
they fully merit protection by the farmer. 
OTHER BIRDS. 
Members of the order Herodiones, including herons, storks, am 
ibises, are usually persistent enemies of meadow mice. Many o 
them frequent meadows and swamps, especially in the breeding sea- 
son. Unfortunately, the summer range of the larger number of spe 
cies is too far south to bring them much in contact with voles. How- 
ever, a few species spend the summer where mice abound and makj 
them an important part of their food. 
Of our herons, the American bittern (Botaurus lentiginoms) is 
probably the best known destroyer of voles. The bird is a summer 
resident in all suitable localities in temperate North America, making 
its home in moist meadows, bogs, and swamps. Baird, Brewer, and 
Ridgway say of it : " It does not move about much by day. although 
it is not strictly nocturnal, but is sometimes seen flying low over the 
marshes in pursuit of short-tailed or meadow mice, which are fre- 
quently taken whole from its stomach.'' ° Records of the Biological 
Survey contain a number of instances in which meadow mice were 
found in stomachs of this species. 
Among other Herodiones that feed upon meadow mice are the least 
bittern (Ardetta exilis)^ wood ibis (Tantalus loculator), great blue 
heron {Africa herodias), American egret (Herodias egretta). snowj 
heron (Egretta candidissima) , and the black-crowned night heron 
{Nycticorax nycticorax ncsvius). While frogs, fish, and fresh-water 
crustaceans form the major portion of their food, they feed also upon 
mice, shrews, and other small mammals. As a group they undoubt- 
edly effect a reduction in the numbers of meadow mice in America. 
During a plague of field mice {Peromyscus in this case) in South 
America in 1872-73 Mr. W. H. Hudson observed that storks became 
a The Water Birds of North America, vol. 1, p. 70, 1884. 
