68 



Bird Day Book 



which the bluebird is held, the month of May, for instance, charging 

 them against the bird to the extent of 36.61 per cent of the food, and 

 every month recording them in such quantities as to indicate that 

 they are very palatable to the bluebird. Few birds exceed this 

 record of destruction of useful beetles, but it must be remembered 

 that for the year they form only about one-tenth of the food, and 

 that the remaining food shows that insects as a whole are attacked 

 so impartially that the balance of nature is not disturbed, and while 

 one kind of insect life is not exterminated another is not allowed to 

 become superabundant ; grasshoppers, for instance, enter the food of 

 the bluebird about in proportion to their abundance. 



"The group third in order of importance in the animal food 

 contains the many forms of caterpillars, including a few moths (9.59 

 per cent). Chief among these are the owlet moths, the larvae of 

 which are the well-known cutworms, but there are also included 

 hairy caterpillars and the "yellow bear." The rest of the animal 

 food is made up of flying insects, as wasps, bees, and flies, in small 

 quantities, for the bird is not very active on the wing; of ants and 

 bugs, among which later stinkbugs predominate; remains of chinch 

 bugs, detected in one stomach; a few spiders (2.47 per cent) ; still 

 fewer myriapods, or thousand-legs (1.23 per cent) ; a mere trace of 

 sowbugs and snails ; and a few bones of lizards and tree frogs. 



"The vegetable food consists largely of fruit obtained from 

 pastures, swamps, and hedgerows, rather than from gardens and 

 orchards. Practically all the domestic fruit taken was secured in 

 June and November, and the only cultivated species identified were 

 cherries and raspberries or blackberries. In December, wild fruit 

 forms two-thirds of the monthly food, but this item decreases grad- 

 ually each month, and in May no fruit of any kind is taken. The 

 yearly average is about a third of the total food. As fruit is taken 

 chiefly in winter, it follows that it is eaten to tide the bird over until 

 insects are again abundant, partly taking the place of Seeds in the 

 winter diet of birds in general, though seeds, too, are occasionally 

 and sparingly eaten by the bluebird. Among them are seeds of 

 sumac of both harmless and poisonous kinds, bayberry, and a little 

 indeterminate vegetable refuse and rubbish, together averaging 7.21 

 per cent of the yearly food. 



"The bluebird has never been accused, in the writer's knowl- 

 edge, of objectionable habits, and cultivated crops are not only safe 

 from its attacks, but are benefited by its ridding them of an over- 



