16 BIRDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 



Of the contents of the 27 stomachs, 78 percent consisted of animal 

 matter, nearly all of which was either insects or spiders. The remain- 

 ing 22 percent was made up of various vegetable substances. In the 

 relative proportions of animal and vegetable food the California bird 

 differs somewhat from the eastern subspecies, the diet of which con- 

 sists of 68 percent of animal matter to 32 of vegetable. 



Animal food. — Of the various items in the food of the western 

 hairy woodpecker, the most important, as well as the largest, is the 

 larvge of wood-boring beetles (Cerambycidse and Buprestidse). These 

 aggregate for the year nearly 49 percent of the total. This is a much 

 greater proportion than is eaten by the eastern subspecies, and is 

 probably not exceeded by any other bird. Each of several stomachs 

 contained more than 20 larvse. When the immense damage done by 

 these borers to forest trees, as well as to orchards, is considered, it is 

 hardly possible to overestimate the value of this woodpecker's serv- 

 ices. Moreover, these insects are concealed and protected from the 

 attacks of all birds except those of this family. Most of these insects 

 are taken in the cooler months, the fewest being eaten in July. One 

 stomach taken in February contained 70 percent of wood-borers, and 

 the remainder, or 30 percent, consisted of other harmful beetles. 

 Two stomachs taken in April contained an average of 76 percent of 

 these destructive borers and 6 percent of other beetles. Beetles 

 belonging to various families, nearly all of them harmful, and some 

 very injurious, amount to over 9 percent of the food. 



Ants are usually a favorite article of food with woodpeckers, but 

 with the California hairy woodpeckers they constitute less than 3 

 percent of the year's food. This is somewhat surprising, as the 

 eastern bird eats them to the extent of 17 percent. Other Hymenop- 

 tera, including wasps, amount to less than 2 percent. 



Caterpillars exceed 11 percent, and stand next to beetles in im- 

 portance. Many of them are of wood-boring species and evidently 

 were dug out of trees. 



A few miscellaneous insects and some spiders complete the animal 

 food. Several stomachs contained segments of millepeds, or thou- 

 sand legs, and one held the remains of one of those bristly creatures 

 known as jointed spiders (Solpugidse). 



Vegetable food. — The vegetable part of the diet may be divided into 

 fruit, seeds, and miscellaneous substances. Fruit amounts to 6 per- 

 cent, and consists of the smaller kinds, probably mostly wild species. 

 Rubus seeds (raspberry or blackberry), found in several stomachs, 

 were the only fruits positively identified. Seeds aggregate nearly 12 

 percent, and all that were determined belonged to coniferous trees. 

 The miscellaneous part contains a little mast and some cambium, 

 or inner bark, but is mostly rubbish, such as rotten wood, probably 

 swallowed accidentally with the beetle larvse. 



