There are 210 species of insect-eating birds known as woodpeckers, living in forests in every continent (1) Australia and Antarctica. They eat mostly (2) or insect larvae, which they find living under bark. They reach their food by drilling holes in (3) with their beaks. They have several characteristics that help. in their survival. For example, their short, strong legs have four (4) toes. Two of the toes extend (5) ; the other two go back- ward. This helps the bird hold its (6) when it clings to the side of a tree. This bird’s most unusual quality is its (7) to bore holes in wood to get its food. To do this, it has a chisel-like (8) . It is shaped so that it can drill deep into the (9) and wood of almost any tree. The woodpecker also has a shock-absorbent, thick-walled skull that allows it to use its beak as a drill without giving itselfa (10) . It even has a (11) tongue that is both barbed and sticky at its tip, (12) that it can dig insects out of the holes it makes. The green woodpecker lives in the forests of Eurasia(欧亚大陆) and (13) to about twelve inches. It has olive-green feathers (14) its back and wings; its head and belly are gray. (15) woodpecker found in Europe and Asia Minor is the great-spotted woodpecker. Of the North American woodpeckers, the (16) is the ivory-billed woodpecker. Birdwatchers have a very difficult time (17) this large, shy bird. On the other hand, the (18) most common woodpeckers found in North America are the downy woodpecker and the hairy woodpecker. (19) have black and white feathers. The males also grow a red patch on their heads. The downy woodpecker is about six inches long, (20) the hairy woodpecker may reach ten inches.