NORTHERN SHRIKE 117 



have amounted at the end of the first year to 118,800, and at the end 

 of the second year to 1,306,800 individuals." 



In addition to the three named above, he lists the following birds 

 that this shrike has been known to kill: Chickadee, snow bunting, 

 downy woodpecker, vireo, kinglet, field sparrow, goldfinch, siskin, 

 myrtle warbler, mourning dove, cardinal, longspur, and horned lark. 



Among mammals, meadow mice {Microtis) seem to be the most 

 frequent victims, but Judd also lists the white-footed mouse {Peroinys- 

 cus) and the harvest mouse {Reithrodontomys) , He continues: 



Carrion is sometimes eaten. Pi'of. F. E. L. Beal, while at Ames, Iowa, In 

 January, 18S0, saw a butcherbird fly over the brown frozen prairie to a carcass 

 of a cow, where it lit on one of the ribs and greedily tore off shreds of the flesh. 



Active insects are much more liable than sluggish ones to fall victims to the 

 butcherbird, because objects which at rest can not be discriminated are instantly 

 seen when moving. Thus it happens that flying grasshoppers and running beetles 

 form a large proportion of the food of this bird. Grasshoppers and crickets 

 (Orthoptcra) , which are eaten during every month from October to April, form 

 24 percent of the total volume of food, and for October and November together 

 these insect pests form more than half of the food. Compared with Orthoptera, 

 the beetles (Coleoptera) eaten are of minor importance, amounting to only 6 

 percent of the food. More than half of these beetles belong to the family 

 CaraMdae, the members of which prey upon insect pests. Caterpillars were 

 contained in one fifth of the stomachs examined, and during the months of 

 January and February amount to 8 percent of the volume of the stomach con- 

 tents. Dr. A. K. Fisher collected in March two stomachs that were full of 

 caterpillars. Even the bristly Isabella caterpillar is eaten, an object apparently 

 as edible as a chestnut bur. Cutworms were found in several instances, but 

 moths were seldom met with. Ants, wasps, flies, and thousand legs are some- 

 times eaten, and spiders constitute 3 percent of the food ; but bugs (Hemiptera) 

 were not detected during our laboratory investigations, though a cicada sup- 

 posed to have been impaled by a shrike was found by Mrs. Musick, at Mount 

 Carmel, Mo. * • * 



The present investigation shows that beneficial birds form less than one- 

 fourth of the food of the butcherbird. It also shows that the butcherbird, in 

 addition to being an enemy of mice, is a potent check on the English sparrow, and 

 on several insect pests. One-fourth of its food is mice ; another fourth grass- 

 hoppers ; a third fourth consists of native sparrows and predaceous beetles and 

 spiders, while the remainder is made up of English sparrows and species of 

 insects, most of which are noxious. 



The amount of insect food taken by the northern shrike, as stated 

 above, seems surprising. The stomachs examined must have been 

 taken largely in the southern extremes of its winter range, or in fall 

 or spring, for the shrike would not be likely to find flying or crawl- 

 ing insects in New England or in the Northern States in the dead of 

 winter; but grasshoppers are often available in New England in 

 October, and even in some Novembers, and other insects in March. 



Dr. Miller (1931) adds the following birds to the list mentioned 

 above, as taken by the species, including both subspecies: Hairy 

 woodpecker, phoebe, white- winged crossbill, redpoll, titmouse, bush- 



