CROWS, CUCKOOS, AND SHRIKES. 51 



vour the young and not infrequently catch the adults as well. By 

 far the greater number of the mice found in the stomachs were 

 meadow mice, or voles (genus Microtus), and most of them were the 

 common species (Microtus pennsylvanicus) ." 



In midwinter, when the ground is covered with snow, crows find 

 but few field mice; but as spring approaches and the snow begins 

 to melt on the meadows, the bulky grass nests of the mice are first 

 exposed. The crows may then be seen searching the meadows for 

 them. They alight near the openings in the snow, pounce upon 

 the nests, tear them to pieces, and as the mice scamper out the crows 

 often succeed in capturing them. Later in the spring, when crows 

 feed their nestlings, insects are more abundant and the nests of mice 

 are hidden in the growing grass, so that relatively fewer mice are 

 eaten. Still later, after the young crows have left their nests and 

 mowing machines have once more exposed mouse nests in the mead- 

 ows, crows again spend much time searching for young meadow mice. 



It is of interest to note that complaints of recent depredations of 

 field mice are especially numerous from sections of the United States 

 where for several years past bounties have been paid for killing crows. 



CUCKOOS AND SHRIKES. 



The larger species of the family of cuckoos (Cuculidce) are known 

 to feed extensively upon vertebrates. The two more common cuckoos 

 of the United States are too small to share this habit, but the road- 

 runner (Geococcyx calif omianus) of the Southwest feeds rather 

 commonly on reptiles, batrachians, and small rodents. Prof. F. E. L. 

 Beal captured one in California which had eaten a field mouse 

 (M. calif ornieus). 



The great northern shrike (Lanius borealis) is a common winter 

 visitor in the northern half of the United States. It arrives from the 

 north in October and remains until March or April. It is a familiar 

 bird to most residents of rural districts. Gray in general color, with 

 black wings, conspicuously barred with white, and with white in the 

 tail, it looks much like a mocking bird, but has a strong, sharply- 

 hooked bill, which enables it to kill small birds and mice. In its sum- 

 mer home it is probably much more insectivorous than with us. It 

 comes to the United States at a time when insects are not abundant, 

 and feeds mainly upon small birds, mammals, and grasshoppers. 

 Mice were found in one-third of the stomachs examined by the Bio- 

 logical Survey and more than half of those identified were meadow 

 mice. Doctor Mearns is quoted a as authority for the statement that 

 in Minnesota during March shrikes live almost exclusively on meadow 

 mice. Most farmers have noticed that the northern shrike, or 

 " butcher bird," catches meadow mice. The birds are often seen at 



« Bulletin 9 of the Biological Survey, Cuckoos and Shrikes in their Relation 

 to Agriculture, p. 19, 1898. 



