SYSTEM NOTICE

Auto translation by AI. Be sure, accuracy, nuances and authorial intent may not be fully reflected.

Sunset Operation on the Shores of Lake Biwa 2025 No. 33 What is the relationship between Tundra Swans and ducks?

2025年12月12日 05:56

Today the weather was wonderful and there was no wind. Since Lake Biwa was calm, I thought there would surely be Tundra Swans, so I went out to the usual shore, and sure enough, they were there. (^^)

The first photo of the day, taken while hiding so as not to startle them. Although, Tundra Swans don't run away even when they see people.

In previous years, many flocks used Lake Biwa as a roost and went to rice paddies rich in food to feed, and families feeding on Lake Biwa itself were rather few. However, this year, I see many Tundra Swans feeding on Lake Biwa right in front of where I do my fixed-point photography. Perhaps it is because there are fewer days with seasonal winds and the waves on Lake Biwa are calm?

The dragon of the day. Delighted with the sunset in its mouth. lol

And, ducks always follow Tundra Swans when they feed. Today, let's talk a little about their relationship with those ducks.

The main reason ducks gather around Tundra Swans is by no means because they are friends.

Taking advantage of the fact that the Tundra Swans don't get angry even when they are nearby,

they are cleverly benefiting by utilizing the Tundra Swans' foraging behavior.

There are various types of ducks that swim with Tundra Swans or forage nearby, but Northern Pintails, Mallards, and Tufted Ducks are particularly common.

Tundra Swans use their long necks like this to eat the roots and rhizomes of aquatic plants on the lake bottom.

Since they cannot dive that deep, the ducks wait for the food that is usually out of reach to float up into the water when the Tundra Swans peck at or dig up the lake bottom, and then they eat it.

It's fine because the Tundra Swans are indifferent and magnanimous,

but it would be a disaster if they got angry. After all, they are huge, have long necks, and are very fierce. (^^;)

Hmm. I wonder if this counts as a "symbiotic relationship." But wait, it's beneficial for the ducks, but not for the Tundra Swans, so maybe it's different? When I looked it up, a symbiotic relationship is defined as a relationship where different types of organisms live together while influencing each other and is generally classified as follows.

Mutualism... A relationship where both organisms benefit.
Commensalism... A relationship where only one organism benefits, and the other receives neither benefit nor harm.
Parasitism... A relationship where one organism benefits, but the other organism is harmed.

I see. The relationship between ducks and Tundra Swans is commensalism. In short, it's the same as a remora sticking to a large whale to get leftovers.
I had assumed that a symbiotic relationship meant that both sides benefit, so I was surprised that even parasitism, where one organism is harmed, falls into this category.

Yes, well, from here on, let's wait for the moment the Tundra Swans take flight to return to their roost.