NATURE IN SHORT / Swans feed on plants with economic, ecological, cultural value

Kevin Short / Daily Yomiuri Columnist

The Asian New Year is fast approaching. The last moon of the old year is already a waning gibbous. Look for beautiful Selene rising in the east a bit after 9 p.m. tonight. If you miss her then, try again in the west tomorrow morning.

At this time of year, I find that most of my country rambles get started from mid- to late afternoon. I usually head out around 2 p.m. or 3 p.m., then come back just after sunset, which today happily is a full five minutes later than last Thursday.

Even if I get a later start, I can still enjoy a short walk with lots of good nature to relate to. In fact, I consider myself very fortunate because I can enjoy watching a small flock of swans on a chosetsu-ike reservoir that is adjacent to my condominium.

These are whooper swans, called ohakucho or "large swan" in Japanese. They can be told from other species by the distinctive yellow markings on their bills, which extend from the base forward to a point in front of the nostrils. Whoopers are Eurasian swans, closely related to the Trumpeter Swans of North America. They breed on lakes and marshes in the subarctic zone, and winter in the cool temperate areas. Here in Japan, they arrive in Hokkaido in mid-autumn, and gradually move southward as the weather chills.

Swans winter on this pond every year. Right now, eight birds have moved in. One of these is very gray, with white rather than yellow markings on its bill. This is clearly a juvenile, just fledged this summer. The other seven are various shades of white, with the characteristic yellow bill markings. These may represent one or several related or extended families, including several nonbreeding adolescents left over from last year's clutches.

Swan families are known to stick together and to return to the same wintering grounds year after year, and the big birds do not begin breeding until at least their third year.

The swans spend a lot of time feeding. Sometimes they appear to be filtering small pieces of plant matter floating near the surface. Other times they stick their long necks deep into the water, often even turning their bodies upside down, with tail pointing straight up. This maneuver allows the big birds to extend their necks even deeper down.

By far and away, the swan's favorite feeding area is in or along a rich community of wild rice that has established in the shallows near the northern end of the pond. The swans are clearly gorging themselves on something that grows in the water at the base of these aquatic plants.

Wild rice are truly amazing plants, with great economic, ecological and cultural value. There are four species, three of which are native to North America and one to Asia (Zizania latifolia). The Asian species, called makomo here, is widespread throughout Japan. Wild rice is not the progenitor of cultivated rice, but is a close cousin in the Grass Family (ine-ka). The plants are big, tall perennials with long, thick leaves and a straight flower stalk that stands up to two meters high. Their preferred habitat is shallow water around the edges of ponds, lakes and slow-flowing rivers and streams.

The grains of wild rice are edible, and also equipped to fly around on the wind. Once a plant is established, it sends out a network of new underground shoots in the bottom mud. My local community is very robust, with dozens and dozens of thickly clustered plants.

The swans may be feeding on tender new shoots that grow from the base of the wild rice plants. Sometimes smaller birds, such as gallinule (ban), coot (oban) and green-winged teal (kogamo), crowd around a feeding swan. The swans' powerful, energetic yanking activities rip up chunks of shoot and runner, which are snapped up by the other birds, who get a free meal while letting the swan do all the work.

Wild rice plays a vital ecological role in shallow wetland ecosystems. The plants, however, are also special to people as well. Since ancient times the long leaves have been used to weave mats and other items. In a love poem from the Manyoshu, Japan's first collection of poetry compiled in the eighth century, the male writer croons that he would not feel a chill even if he had to sleep all night on a single thin mat woven of wild rice leaves, as long as his love was lying beside him.

Wild rice leaves were also traditionally used as compost and livestock fodder, and the tender new shoots were eaten as a wild vegetable. So valuable were these plants that villagers often planted and maintained them.

In addition, makomo is frequently treated as a sacred plant. According to one legend, the historic Buddha is said to have cured illnesses by having patients lie down on mats woven of wild rice. In Japan as well, makomo straw is often used to weave the shimenawa ropes that mark off sacred space around Shinto shrines, as well as straw figures and boats for the summer Buddhist Bon festival. Huge rings of woven leaves are sometimes found at shrines and temples. Visitors walk through the rings as a means of avoiding illness or bad luck.

I also consider myself lucky to have several iigiri trees in my local park. These are medium-size deciduous trees native to the warmer areas of East Asia. In the Kanto region, they rarely appear in the native woodlands, but grow well in parks and gardens. At this time of year, most of the leaves have wilted off, but the branches are richly decorated with large, densely packed pendant clusters of the brightest orange-red berries imaginable. These berries attract numerous songbirds, especially the brown-eared bulbul (hiyo-dori) and azure-winged magpie (onaga).

Short is a naturalist and cultural anthropology professor at Tokyo University of Information Sciences.