Of the vegetable food, acorns formed 10 percent of the yearly food; grains, including rye, corn, barley, and oats, amounted to 4 percent; fruits, averaging 15 percent, included pears, apples, grapes, cherries, and prunes; and the other 17 percent was made up of wild fruits, such as pepperberries, elderberries, and gooseberries and the seeds of the poison oak and sumac and of a few weeds. He says of the poison-oak seeds:
The consumption of these seeds would be a decided benefit to man if they were ground up and destroyed in the stomachs. Unfortunately they are either regurgitated or pass through the intestinal tract uninjured and ready to germinate. The action of the stomach simply removes the outer covering, a white, wax-like substance, which is probably very nutritious, and is evidently relished by many birds. Birds are probably the most active agents in the dissemination of these noxious shrubs. On the other hand, these seeds, which are wonderfully abundant, afford food for thousands of birds during the winter, when other food is hard to obtain, and thus enable the birds to tide over the cold season to do their good work of destroying insects the next summer.
Johnson A. Neff (1928) says that “in a great many instances they are known to feed on the larvæ of the codling moth”; and that “ants were the largest item of food for the year, averaging 40.30%, taken during every month; several stomachs held over 2,000 each, and many of them contained over 500.” Among the vegetable food he lists manzanita berries and seeds and such wild fruits as madrona, dogwood, haw, serviceberry, elderberry, Oregon crab, and huckleberry; seeds of poison oak averaged 7.5 percent, but in December the percentage was 33.3.
Referring to the fruit-eating habits of this flicker in Los Angeles County, Calif., Robert S. Woods (1932) writes:
Fortunately for the grower, and perhaps for the birds as well, the rind of an orange is impervious to the attacks of any ordinary bird, though when once opened the fruit is well liked by many of them. Only the Red-shafted Flicker (Colaptes cafer collaris) is able to chisel through the tough skin; after making a round opening large enough for the insertion of its bill, it scoops out a large portion of the pulp with its tongue. Examples of this sort of damage, however, are infrequent and usually, as it seems, in oranges which have fallen to the ground, where they are more easily reached.
The flicker’s attacks on avocados appear more serious, though this is partly due to the smaller numbers of the fruit available. Avocados which hang near a convenient perch are often found to have a roughly circular hole extending through to the seed. In a few of the fruits these holes have been considerably enlarged, but usually they are not much larger than the base of the bird’s bill.
Jack C. von Bloeker, Jr. (1935), saw three red-shafted flickers capture scarab “beetles in flycatcher fashion. In each case, the bird attained a position behind its intended victim, then, taking up the erratic zigzag course of the beetle, suddenly swooped down and captured it in mid-air.”
Major Bendire (1895) also says: “Besides the usual insects and larvæ upon which this species feeds, I have seen it catch grasshoppers, both on the ground and on the wing, and it is likewise very fond of wild strawberries.”
Behavior.—I can find nothing in the behavior or general habits of the red-shafted flicker that is essentially different from the habits of the northern flicker. It has the same annoying habit of drumming on the resonant parts of dwellings at early hours in the morning, which is quite disturbing to sleepers. It also does considerable damage to buildings by drilling holes in the eaves or walls for nesting or roosting places, spending winter nights or even stormy days in such sheltered retreats. John G. Tyler (1913) says on this subject:
Unfortunately these handsome birds have fallen into disfavor among a large number of both city dwellers and country residents, on account of their habit of drilling holes in the gable ends of buildings. When once a house has been selected it seems that nothing short of death will cause them to cease their drilling operations until one, and in some cases three or four, holes have been cut through the outer wall of the building. Whether these holes, which are generally made in the winter, are excavated for roosting places or simply through a sort of nervous energy seems a matter of doubt; but certain it is that the birds spend much time in them as soon as they succeed in completing their work. It is a common sight, on rainy days, to see a Flicker’s head peering out from his open doorway.