460 MICHIGAN BIRD LIFE. 
23 per cent of the food. It is hardly necessary to point out the importance 
of these facts. Remembering that, especially in August, the blackbirds 
are feeding in large flocks it is easy to see that at this time they must 
consume grasshoppers by the million. Caterpillars formed 8 per cent of 
the food in May and 4 percent in June; not a large amount, but forming 
nevertheless an important item; many of the caterpillars eaten are cut- 
worms, and among these the army-worm was recognized in six stomachs. 
The Grackles eat large numbers of spiders, but these probably have small 
economic significance. 
Practically the only harm done in the course of the insect-eating is the 
destruction of a considerable number of predaceous beetles, ground beetles 
belonging mainly to the family Carabide. The largest percentage of these, 
13 percent, was found in June, and this would indicate that the birds were 
doing some harm, for these beetles feed mostly upon other insects and are 
therefore potentially beneficial. It must be remembered, however, that 
these beetles are abundant at all times of the year, that they are con- 
spicuous by their size and activity, and also, being often strong-scented, 
are not generally eaten by other birds. It is therefore natural that a bird 
like the Grackle should eat a considerable number of them, especially 
as the taste and odor do not seem to be disagreeable. 
Taken all in all the facts seem to show conclusively that in the long run 
the Bronzed Grackle is a valuable bird which does considerably more good 
than harm, but the manner in which this good and evil are distributed 
makes it impracticable for the average farmer to tolerate the bird invariably. 
The good done is widely distributed; the harm is often concentrated on a 
few acres. So long as the birds are but moderately abundant the good done 
is pretty sure to outweigh the harm, even in the case of the fruit grower, 
market gardener or small farmer; but when they become superabundant 
instances of great injury are sure to occur and much complaint will follow. 
It seems probable that it will be best not to attempt to protect the Grackles 
by law at present, but to try to teach the farmer to let them alone so long 
as they are doing no visible harm, only striving to limit their numbers 
or drive them from his fields when they threaten serious injury. 
The Bronzed Grackle is one of the few birds for whose vocal performance 
little can be claimed. It has nothing which, even by the most imaginative, 
can be called a song, and its usual love notes have been aptly likened to the 
creaking of a rusty hinge. In the case of other blackbirds numbers 
sometimes modify the character of the individual performance so that a 
chorus is musical, but in the case of the Grackle the larger the number 
the greater the discord. 
TECHNICAL DESCRIPTION. 
Adult'male: Head and neck all round, metallic black, with purple, violet, blue or green 
reflections; rest of the body plumage above and below, black, with a distinct brassy gloss, 
the line between neck and body sharply defined; wings and tail with purplish or violet 
gloss, never bluish; bill and feet black; iris bright yellow. Adult female: Decidedly 
smaller and duller, the head and neck not noticeably different, but the body plumage 
lacking much of the metallic luster. Young: Similar at first to adult females, but even 
duller, the body plumage mostly slate color, with no metallic reflections; before moving 
southward, however, the sexes are distinguishable by the plumage. 
Male: Length 12 to 13.50 inches; wing 5.45 to 5.95; tail 5.25 to 5.90 (its graduation 
1.15 to 1.60); culmen 1.12 to 1.26. 
Female: Length 11 to 11.50 inches; wing 5 to 5.25; tail 4.80 to 4.90. 
