A small group of mallard ducks near an aquarium here have started behaving unusually, diving underwater and looking for food, it has been learned.
The behavior was observed in the ducks in the Chitose River next to the Chitose Salmon Aquarium beginning this month.
"They don't swim very skillfully, but they dive and search the bottom (of the river)," said Yorika Arakane, a curator at the aquarium. "It was the first time I've seen this and I was surprised."
Ducks in Japan can basically be divided into two categories: diving ducks that dive under the water and catch fish and shellfish, and freshwater ducks that float on the water and only poke their heads under the water to eat weeds. Mallards, whose distinguishing features are their green head and yellow beak, belong to the second category.
Arakane said there were about 10 mallards, which had flown in with tufted ducks, which are diving ducks, and other birds. The mallards reportedly began diving under the water in the river next to the aquarium. When viewed from the river observation window in the aquarium, they can be seen apparently eating salmon eggs.
"Not just mallards, but also spot-billed ducks which are not thought to dive, go under the water and eat acorns, but there have been few observed cases," said Kazuyuki Kuwahara, a curator at the Natural History Museum and Institute, Chiba. "Mallards, however, feed mainly on plants, and I've never heard of them eating salmon roe," he said. (Mainichi)