Woodpeckers spend a great deal of their time pecking wood and chiseling bark off trees. They do this for several reasons—to search for their principal food of wood-boring arthropods, to excavate their nesting and roosting cavities, and to proclaim their territory and impress potential mates by loud drumming. Woodpeckers accomplish these tasks by hammering vigorously at softer, fungal-rotted parts of living and dead trees, using their chisel-shaped bill. In their territorial drumming, however, woodpeckers tend to choose more resonant, unrotted trees. Some woodpeckers habitually use telephone poles and tin roofs as their sonorous drumming posts. Both males and females engage in drumming displays, which may be supplemented by loud, raucous, laughing calls. Woodpeckers use their cavities for both nesting and roosting. Although both sexes participate in brooding the eggs and young, only the male bird spends the night in the nesting cavity.