16 cCUCKOOS AND SHRIKES IN RELATION TO AGRICULTURE. 
The habit of killing small animals and hanging up their bodies has 
given the shrike the appropriate generic name Lanius, which means 
‘butcher.’ The name ‘Butcherbird’ is more properly applied to the 
larger northern bird, while to the smaller and more southerly species 
the title ‘ Loggerhead’ shrike is given. 
Difterent diets affect in time the structure of an animal. Special 
parts are developed for procuring and digesting food. But the réle 
that food habits play in the production of such variations has not yet 
been fully worked out. All structures are necessarily developed and 
maintained in direct relation to function. Shrikes have special struc- 
tures suited to their peculiar feeding habits. So long as the northern 
shrike or butcherbird is restricted to an animal diet, because of the 
relative scarcity of insects at the North during most of the year, it 
must be more of a meat eater than its southern cousin, the loggerhead. 
The struggle for existence in the North is so keen that the butcher- 
bird, during cold weather, must hold itself in readiness to fly at the 
first bird or mouse that is sighted. 
The food habits of the shrikes, so far as determined from the exami- 
nation of 155 stomachs, collected during every mouth of the year, from 
Saskatchewan to Florida and from the Atlantic to the Pacitic, are very 
similar to those of the sparrow hawk; that is to say, the food con- 
sists of mice, small birds, and insects, the latter mainly grasshoppers. 
Both birds are much less insectivorous in cold than in warm weather— 
the oncoming of winter and consequent increasing scarcity of insects 
necessitating a change in food. 
In discussing the insectivorous habits of the shrike, it is hardly nec- 
essary to state that the destruction of grasshoppers is a great service 
to the farmer. The shrike also devours a large number of beetles, and 
often eats caterpillars, wasps, and spiders. Since it takes practically 
no vegetable food, it can not injure crops, unless indirectly, by killing 
birds and insects that prey upon insect pests. The birds selected, 
however, are for the most part seed eaters and consequently less valu- 
able than the insectivorous kinds; and if it be granted that the harm 
done by the destruction of one of these birds is counterbalanced by 
the killing of one mouse, then it follows that the harm done by the 
shrike in killing birds is completely offset. Furthermore, the attacks 
of the shrike are often directed against the English sparrow, now so 
obnoxious in many parts of the United States. Concerning the insect 
food, it may be safely stated that the percentage of noxious grass- 
hoppers is four times as great as that of the useful ground beetles. 
In considering the relation of the shrikes to agriculture, it must be 
remembered that one inhabits a fertile country where cultivation yields 
heavy crops, while the other lives in a northern region where agricul- 
ture amounts to very little. Therefore, the good or harm done by the 
northern butcherbird must be mainly accomplished when it migrates 
south into the United States. From the present limited investigation, it 
