A Wonder of Evolution - Woodpeckers
'Through the Lens', Fujingaho Magazine, June 2016
Photos and text: Her Imperial Highness Princess Takamado
English Translation: Asia Club, WBSJ Volunteer Group (Anna THOMAS & KASE Tomoko)
Woodpeckers are mysterious birds. They are even well-known to children because their endearing, unique appearance and habits make them good material for picture books and comics. When I was around four living in America I loved to make my parents laugh by mimicking Woody Woodpecker which was a popular character at the time.
There are over 200 species of woodpecker in the world, with most of these belonging to the Picinae subfamily. There are 9 species from the subfamily in Japan: they’re well-known birds, as some species can be seen in cities. They flap their wings and rise up, and once they gain some speed they close their wings flying in a wavelike pattern, so you can follow them with your eyes and see what tree they land on. They climb up trees, hunt for insect grubs and such hiding inside trees, and have nests in holes they bore in tree trunks. This is all thanks to their distinctive shape which allows them to perch vertically on tree trunks. Their feet have two toes pointing forward and another two pointing backwards, with sharply curved claws, and the four feathers in the center of their tail have very hard, curved shafts. In short, they support their bodies on three points: the claws of each foot and the hard tail.
When woodpeckers search for food or bore holes to make their nests, they peck trees without rhythm and not very loudly, but during breeding season they drum regularly to announce their territory. Drumming, like calling, is for letting surrounding birds know of their presence, so they use trees that resonate well. The sound and pattern varies by species, but what can be said about all of them is they strike a tree at a high speed in one spot with their beaks. This apparently delivers the same impact as a human would get by repeatedly striking a wall at a speed of about 25 kilometers per hour. Of course, everyone wonders why this doesn’t cause a concussion. While I understand the merit of avoiding competition by only using tree trunks that other birds don’t use, I want to ask, “Do you really need to go that far?”
The bodies of woodpeckers structurally produce strong blows and moderate and diffuse the shocks delivered. For example, the skull is thick and composed of sponge-like hollow bone that wraps around the brain like packing material. The brain is relatively light only at 0.1-0.5 grams, has few wrinkles on its surface and is tightly packed within the skull, making it hard for the brain to move against an impact. The beak is flexible, almost straight with a thick base, and the lower beak is shorter than the upper. Furthermore, the base of the long tongue is on the back side of the bird’s head: the bone at the base of the tongue wraps around the skull curving from the jaw to back of the skull to the crown, then to the front of the head and ending at the nasal cavity, functioning almost like a seatbelt. Such an evolution is truly interesting.
Japanese Pygmy Woodpeckers and Japanese Green Woodpeckers can be seen in city parks as well as in golf courses. When they notice they’re being watched, they quietly slip behind a tree, peeking out to check what we’re doing. This movement is cute and fascinating, but this is the same action as using a tree as a shield to hide when predators like hawks and crows are near. June is just the time when these woodpeckers raise their chicks, so it’s important to leave them alone, especially when a nest is nearby.
As I greatly appreciate the fascinating evolution of woodpeckers, I want to be mindful to continue keeping an eye on the various fascinating things about the natural world in everyday life.