The Town Where Kingfishers Live

I also only started properly observing kingfishers in Tokyo in 2021. Based on those results, I published my recent book, "Kingfisher City Tokyo." I had heard they were around, but I had never looked for them seriously.

There is no doubt that the urban environment is becoming increasingly favorable for kingfishers, and their numbers are growing. I believe we need to re-evaluate urban nature, using the kingfisher as a starting point.

Since I couldn't go anywhere due to COVID, I tried walking along River A near my home, which flows through the city center and is a typical urban river lined with concrete on three sides. Textbooks always say that such artificial rivers are difficult for living things to inhabit, and it used to be said that kingfishers couldn't live there because they couldn't dig nesting burrows in concrete. So, I hadn't been looking at the river with the expectation of finding kingfishers.

Then one day in May, while I was walking, a neighbor pointed and said, "There's a kingfisher!" After River A, I observed River B upstream, and then River C, another urban river on my commute to the university. I found them immediately at all three locations. It was the start of the breeding season, and pairs were forming.

However, for the first year, I couldn't figure out where the nests they were carrying food to were located.

Where were the nests?

They were in the drainage holes on the concrete side walls. At first, I never imagined such a place would be a nest. I thought they were digging somewhere in the banks of a nearby green space.

At River A, the father was mainly taking care of the chicks. The mother was relatively cold there, and the father was providing food almost entirely on his own (laughs).

River C is a place where huge crowds of people gather during cherry blossom season, but even in the middle of that, they were there as usual. Eventually, I learned that if there are white droppings on the concrete side of the river, you know a kingfisher is there.

What is their main food source?

In River A, it's mostly flathead grey mullet and the invasive Neocaridina denticulata (shrimp). In River B, it's the shrimp. In River C, it's almost entirely the brackish-water Gymnogobius castaneus. Because biodiversity in Tokyo's rivers is low, kingfishers have no choice but to be picky eaters in a sense.

Pure freshwater fish in city center rivers were completely wiped out once in the 1960s due to river pollution. Therefore, only fish that can come up from the sea can inhabit them. The mullet is a typical example.

The Gymnogobius castaneus is a type of goby. Around May or June, thousands of juveniles about 3 to 4 centimeters long come up the river in groups. They especially love rivers like Tokyo's with concrete on three sides, so they can be caught as food in unlimited quantities.

They all take aim and compete for food, saying "Meal! Meal!" (laughs).

Mullets swim fast, so they must be difficult to catch. But the gobies move by clinging to the riverbed, so they can be caught quite easily.

The situation might be better than in my area (Tsukuba City, Ibaraki Prefecture) (laughs).

That's true. River B is relatively upstream and is cut off from the sea, so there are no fish at all. The only food sources are released invasive species: the shrimp and American crayfish.

Are there no tadpoles?

Since it's a river, there aren't any. There are stone moroko (Pseudorasbora parva) in nearby ponds. Quite a few stone moroko remain in ponds in the city center.

The bullfrog tadpoles, known as "Baketama." Kingfishers love those. They were catching them in Koajiro (Miura City).

What was surprising about observing kingfishers in central Tokyo was that, unlike the traditional diagrams of kingfisher habitats found in field guides, they are breeding in rivers lined with concrete on three sides. And they have become completely unafraid of people.

Also, even if the food isn't native Japanese freshwater fish, they are raising their young properly every year even in a biased food environment. In other words, the characteristic of today's Tokyo kingfishers is that they have clearly adapted to the urban environment.

I used to observe kingfishers year-round a long time ago. In the late 1950s, in the lowlands downstream of the Tsurumi River, fragments of the Nikaryo Canal remained here and there. There were large numbers of crayfish in places where the vertical wooden pile revetments were crumbling, and kingfishers would come to eat them.

However, if you went 2 or 3 kilometers upstream from there, I never saw a single kingfisher. At that time, the Tsurumi River was still a natural river, so the banks weren't vertical but gentle, with silver grass and reeds growing. In that environment, kingfishers couldn't build nests.

However, now, in Tsunashima, Kohoku Ward, Yokohama City, which is in that same middle reach, kingfishers are there year-round. This is because dredging was done and the revetments were made vertical. They build nests in the mud walls that are about 3 meters high. Once the river was artificialized, they returned to Tsunashima.

In River A, they fly into nests deep inside drainage holes in a 10-meter-high concrete wall to deliver food.

It's lucky that their food and housing are so close together. In my area, there are irrigation ponds where they catch food, but there isn't suitable soil nearby, so they go back and forth to nests that are quite far away.

Tokyo kingfishers are living in a kind of "tower mansion" (high-rise apartment), living a life where they eat Chinese food and burgers—meaning invasive species—on the first floor (laughs).

In River A, discarded bicycles become artificial reefs where fish and shrimp gather in large numbers, making it a favorite feeding spot for kingfishers. They seem to like places that look dirty at first glance, and they mostly catch the shrimp. And right above that, there's a Japanese rat snake about a meter and a half long.

I bet they occasionally eat kingfisher chicks. Snakes and crows. Also, if they fall into the water, carp will go after them.

Soft-shelled turtles are also common. It's almost like a wild kingdom.

That really changes one's perception.

Exactly. Since I had been looking at nature-rich areas like Koajiro and the headwaters of the Tsurumi River with Mr. Kishi for nearly 40 years, I hadn't really looked at the nature in the city center, even though it was close by. But when you look at the neighborhood, it's incredibly interesting (laughs).

It's because we unconsciously decide that the urban world is a certain way. If you think they can't possibly be here, you won't see them, but if you think they should be here, you start finding them everywhere.

Kingfishers often come to Shinoshibashi on the Furukawa River near Mita. They are also in the pond at the nearby Arisugawa-no-miya Memorial Park. Their home base is the Institute for Nature Study in Shirokane; those living there are the ones making "business trips" out.

In the old days, they probably went to goldfish shops and ate the goldfish.

The area where Roppongi Hills is now was originally a cliff with spring water, and there was a famous goldfish shop there. Ryo Yano, a famous kingfisher researcher at the Shirokane Institute for Nature Study, wrote that he investigated why they were always catching red goldfish and found they were from the goldfish shop in Roppongi (laughs).

That must have been tough for the goldfish shop.

There's this image of kingfishers eating sweetfish in clear streams, but that might be a myth. I'm sure some do, though.

I had a vague idea that there were kingfishers in the city and that they seemed to use drainage holes as nests, but I'm surprised they use them so much and that there is so much food.

The living environment, or rather the effort required, is really much easier than in my area. I think it's probably harder to catch food where I live.

It's not that they are living there "despite being in the city," but rather, if anything, they are "thriving because it's the city." They've become that kind of urban bird.

Urban rivers in Tokyo have become very clean now because the sewage system has developed. However, because most living things were wiped out once, there are few native fish species. As a result, invasive species stand out. But if it's food, kingfishers aren't picky.

The kingfishers at Senzoku Pond near Tokyo Tech are constantly eating juvenile bluegills, which are breeding in massive numbers in the pond.

But there are people who say things like, kingfishers are supposed to eat Japanese fish, so a kingfisher eating foreign fish or shrimp isn't a "true" Japanese kingfisher.

Are there really people like that? That's an interesting way of thinking.

I wonder if it's not okay for them to eat "Chinese food" (laughs).

Another very interesting thing about Tokyo kingfishers is that they go back and forth between rivers and still water, like irrigation ponds.

I see.

When I looked into it, the locations where kingfishers are found in the city center follow a specific topographical pattern. On the west side of Tokyo, there is the Musashino Plateau, and there is a massive aquifer beneath it. At an elevation of about 50 meters, it bubbles up to the surface in various places. Those are places like Inokashira Park and Shakujii Park.

These fairly large springs that pop up here and there become rivers and flow away. Tokyo's urban rivers, such as the Shakujii River, Shirako River, Kanda River, and Meguro River, are all formed in that pattern. Furthermore, springs emerge again at the cliffs carved by the rivers, creating small watershed headwaters. In central Tokyo, these small watershed headwaters are mostly parks, green spaces, or Imperial land. So, city center kingfishers live in places where springs in parks and rivers are paired together.

I see, so that's how it is.

In the case of the Kanda River, places like Chinzanso or the Higo-Hosokawa Garden are right next to it. These are small valleys with a spring in the middle. These are places where people have lived since the Paleolithic period. In short, spring sites are where people want to live.

People seek out water sources, right? And since rivers flow from there and you can catch living things, people have lived in green spaces with springs from the Paleolithic period to modern times. There is always an urban river right in front of those springs. What's interesting is that even today, ultra-high-end residential areas are located around those springs.

So they are prime locations.

Yes. They correspond to the edges of the plateaus. Places like Arisugawa Park in Azabudai. The best example is the Imperial Palace. The area around Mita, where Keio is located, is the same. There are many places where kingfishers can inhabit in high-end residential areas like Shirokanedai's Institute for Nature Study, Mejirodai, Den-en-chofu, and Seijo Gakuen. The settlements formed around the springs of small watershed headwaters are Tokyo's high-end residential areas, and those also happen to be the places kingfishers like.

Until around 1990, there were no kingfishers in city center rivers because the rivers were polluted and living things had died out. On the other hand, kingfishers had already returned to Meiji Jingu, the Shirokane Institute for Nature Study, and the Imperial Palace starting in the 1980s because there was clean spring water and fish. Later, as the rivers gradually became cleaner, some of the birds from the springs began starting "apartment lives" in the urban rivers.

What was surprising was that I couldn't find many papers describing the ecology of breeding in drainage holes. One of the few papers was by Sayako Kuroda, which noted that kingfishers that were in the Imperial Palace or the Shirokane Institute for Nature Study used drainage holes near the Imperial Palace in the 2010s.

I've heard that kingfishers dig new nesting burrows every year because the inside gets dirty with droppings and leftover food. If they use the same drainage hole every year, I imagine the inside would get quite messy.

There are plenty of drainage holes.

In the case of River C, they used one spot they used last year again the following year, but they used different holes in the spring and summer. In other rivers, they change them every year.

So, they have a rotation.

I think so. Last year, when I spent a day following them, the pair spent all day from morning to night searching for holes along a stretch of about 1.5 kilometers. Moreover, there are cases where they prepare another hole as a decoy and pretend to raise young there to deceive natural enemies.

Is that so? They're like northern goshawks.

In my area, there are holes all over the mud cliffs. When they open them, they charge at the mud cliff, and both the male and female call very noisily.

They have a high-pitched call, like "kyo-kyo-kyo-kyo."

That's exactly it. The males are busy making holes, while the females are chirping away actively.

The females egg them on. Two of them line up at the end of a branch, and she tells him to go for it. Then the male charges in. The female cheers him on, but if she loses interest, she just flounces off somewhere else.

Actually, even though there are muddy areas near my house, they seem to go out of their way to use drainage holes. There are two pairs in the retention basin; one has a burrow in the soil, but the other definitely seems to be using a drainage hole.

My family home is in Hamamatsu, and it's exactly the same there. Even though there are earthen walls along the river where they could dig holes, they seem to use the drainage holes. It's easier to catch food at the bottom of a concrete wall with drainage holes. There are young pale chub right under the nest, so they can just catch them one after another.

It depends on how the area behind the drainage hole is constructed. There is a construction method where gravel is placed behind the hole, but if gravel is put in, they can't expand the nest. However, if it's soil, they can expand it, right? It's possible that the kingfishers themselves have developed a culture where they find drainage holes easier, and that is spreading.

Urban rivers are incredibly shallow, with a water depth of only about 10 centimeters. But even in that shallowness, they manage to dive in and catch food with just the right amount of force.

In those places, they probably enter at an angle. If they went in straight, they would collide with the bottom.

They also do very skillful things like hovering at a low height and snapping up prey.

It's like they are experts; they really have a method.

They probably change their diving style depending on the location. They have truly become city kids.

In a few thousand years, I think their genetic habits will change as well.

Looking at Ms. Otaguro's "Birds (Hakken Zukan Plus)" (GAKKEN, supervised by Keisuke Ueda), it was very fun to see that among all the various birds, only the kingfisher appears on multiple pages. First, it appears at the beginning as a town bird, and then it is also introduced as a bird of the satoyama (woodland near settlements).

I was the one who asked for that to be added. I said, "Let's include the kingfisher."

The satoyama one has that orthodox kingfisher feel. Being at the edge of a rice field.

That's how it is at my place.

What's interesting is that it's not just kingfishers; raptors are also increasing in the city. Particularly noticeable is Japan's smallest hawk, the Japanese Sparrowhawk. In a park near my house last year, one was raising its young normally just about 5 meters away from where people were.

There are quite a few raptors in Tokyo.

Above Chinzan-so, where the kingfishers are, Northern Goshawks are often present. There is plenty of food now.

Because there are pigeons.

Pigeons and Rose-ringed Parakeets.

There are a lot of them at Tokyo Tech (Ookayama Campus), aren't there?

The descendants of the birds that originally settled at the Ookayama Campus in the late 1960s grew to about 3,000 by 2015. The parakeets would cluster in the ginkgo trees and be quite noisy (laughs).

However, they scattered in 2016. It seems Northern Goshawks and Peregrine Falcons from the Tama River took notice and came to hunt, causing the parakeets to spread their distribution throughout Tokyo. I just saw some at the Keio Mita Campus a moment ago (laughs).

I want to pick up their feathers (laughs).

I have been watching the scenery of the Tsurumi River since I was a child around 1950, but until around 1990, I never saw a Northern Goshawk flying over the Tsurumi River. Then, entering the 90s, they suddenly began to increase, eating rock pigeons, little egrets, and so on.

One factor is likely that around that time, coniferous trees like cedar and cypress planted after the war reached a diameter of 30 to 40 centimeters, making it possible to build nests. Also, rock pigeons increased excessively. And with the increase of little egrets and black-crowned night herons, the food supply grew.

It's not that things have returned to the way they were. In the past, there was nothing. They have come since urbanization. The Japanese Sparrowhawk came to the Hiyoshi Campus in 2001 or 2002. It built a nest at the top of a fir tree next to the tennis courts in Mamushidani and was fending off crows.

There are Eurasian Sparrowhawks too, right?

The Eurasian Sparrowhawk might have been a bit earlier. Common Buzzards are occasionally seen in the back of Machida.

They were in Shinjuku Gyoen too.

Common Buzzards can be seen relatively anywhere. I think both the Japanese Sparrowhawk and the Northern Goshawk have become urban birds. Common Kestrels, for example, build nests in pairs or trios in large gymnasiums and such.

In the latest bird field guides, Northern Goshawks and kingfishers are listed as urban birds. I don't think that was the case in the early 2000s.

It used to be in the news that if a Northern Goshawk nest was found, construction plans would be stopped immediately.

They aren't raptors, but Little Grebes are also commonly found in places like the Kanda River now.

For birds that swim on the water, like ducks and Little Grebes, the circumstances are completely different. Japanese people tend to think that the cleaner the water gets, the more bird species will increase, but that's not the case.

There is an optimal level of "dirtiness" for each environment. For example, around Tsunashima on the Tsurumi River, the number of species of migratory ducks and grebes was highest around 1990; now there are only two or three species, a drastic decrease. This is because the water has become too clean.

Back when sewage treatment wasn't fully established, when people ground up vegetables in household disposers, all sorts of ducks like Northern Pintails and gulls would gather where the tributaries met the main river to feed on those vegetable scraps when it rained. But now, there's nothing. The ones that do come are Eurasian Coots. I'm not sure why they've increased.

The biodiversity of urban areas, even just looking at birds, is interesting because it breaks simple assumptions. It's like a training ground for a new era of ecology.

In Tokyo's current environment, because old wilderness remains in small river basins, it's not just that kingfishers can return; actually, quite a few precious creatures from long ago remain.

For example, sawtoothed stag beetles are found in large numbers in gardens in the city center; you can see about 50 a day. Also, in another green space in the city center, many jewel beetles emerge in the summer.

Since they aren't creatures that can fly long distances, the greenery at the headwaters of small basins must have been preserved all along, allowing them to survive without going extinct even during the period of high economic growth. This is inside the Yamanote Line. Crows also often come to eat rhinoceros beetles.

There are that many?

Strangely enough, you can see more than in the countryside of Hamamatsu. There are also ebony jewelwing damselflies in the Kanda River.

I had an image of ebony jewelwings being born in the river, going to the forest, and then returning to the river after maturing, but that doesn't seem to matter at all.

We really need to investigate the ebony jewelwing. In the Tsurumi River, they once went extinct from the mouth to the headwaters, but they suddenly began to increase around 2000. And it's not a normal increase; they are even in places where saltwater reaches.

I think it's not the native ebony jewelwing, but a different species that can tolerate saltwater that has come in. I don't know where they came from.

Ryukyu Red-tailed Damselflies appeared in the pond in my garden. I think they were probably attached to the water hyacinths I bought at a home center. I didn't want them to overpopulate, and the water quality of the pond got worse, so I filled in the pond.

But they were very cute. Red and small. I was very happy when they were there. I had a biology teacher come and identify them.

I think various organisms will come to the city.

Golden-ringed dragonflies have been living in the spring water of green spaces in the city center. There are plenty of freshwater snails in a park just three minutes from a station on the Yamanote Line. It was originally a place famous for fireflies. I also commonly see Japanese freshwater crabs. Surprisingly, nature remains in central Tokyo, and the depth of biodiversity is greater than everyone thinks.

And depending on the opportunity, things might recover from there.

Especially since dragonflies and birds can fly. I think things like golden-ringed dragonflies are increasing in the city center. You can see them without having to go to places like Mount Takao.

However, what are most absent from city rivers are the native freshwater fish and shrimp that were originally there. In city rivers, even if you can see kingfishers, you rarely see the silver crucian carp, which used to be the most common freshwater fish in Japan.

There are almost no silver crucian carp. They will never increase unless they are released. However, I believe that silver crucian carp, stone moroko, and medaka fly through the sky. I grew up in a world along the Tsurumi River that was almost destroyed by air raids when I was little. In those places, there were many ponds called bomb craters, and medaka, stone moroko, and silver crucian carp were always there.

I wonder why.

Of course, they spread through flooding, but herons come, get water plants caught on their feet, and fly 50 or 100 meters to the next pond. I think they fly through the air on water plants with fish eggs attached. Since silver crucian carp are parthenogenetic, if just one gets in, they can increase without needing a male and female.

Today, I brought some kingfisher feathers and a picture book of a feather guide I wrote.

It's very interesting; when you look at kingfisher feathers one by one, they are surprisingly plain.

That is structural color, the color emitted when light hits it, so looking at them one by one, they don't look like that cobalt blue. It's not a color the object itself possesses. Like jewel beetles, structural color isn't about being pigmented; there are various pigments slightly deeper than the surface, and the color is created by the transmission and reflection of light.

Looking at this, you wouldn't really think they are kingfisher feathers, would you?

You wouldn't. The flight feathers are also surprisingly plain. Only something like the Oriental Greenfinch is flashy. This one is beautiful.

It's true. The yellow of the Oriental Greenfinch really pops.

It's hard to get an Oriental Greenfinch whole, so I was having trouble when I was making the book. Then, a neighbor brought me a male Oriental Greenfinch, saying a beautiful bird had died. I felt it was a gift from God.

Kingfisher feathers are grown quite densely, aren't they? Since you can only see the tips.

The color itself is a beautiful blue. Is it difficult to draw kingfishers?

The colors are indeed difficult.

With watercolors, it's hard to get those flashy colors, so using acrylics gets you closer to the actual color.

Having observed birds for many years, is there anything about recent birds that you feel has changed?

The number of Ruddy-breasted Crakes around my house has increased. It used to be said that they didn't overwinter in Ibaraki, but they stay all winter now, and there are quite a few of them.

Also, Narcissus Flycatchers have started breeding in the lowlands.

In Tsunashima, Narcissus Flycatchers are singing on apartment balconies. Though they are just passing through during migration in the summer.

Since Narcissus Flycatchers are increasing in the lowlands, I expect they will eventually increase in Tokyo as well.

It's interesting that Ruddy-breasted Crakes are increasing. Last year, near my parents' house along the river where the kingfishers were, I heard a strange voice in the grass and it turned out to be a Ruddy-breasted Crake. They have quite a strange voice, don't they?

That's true. Their alarm call is close to that of a Little Grebe, sounding like 'yurururu.' What's interesting is that they sometimes chirp 'kyururururu' along with the time signal (laughs).

I wonder why Ruddy-breasted Crakes have increased. Creatures like that, who rarely come out of the reed beds.

I wonder why. It's been the last five or six years. They overwinter normally in Ibaraki. Young birds are running around and playing in fallow fields.

Urban kingfishers are fine even if there's a construction vehicle right next to them. They don't mind the noise at all.

Originally, the world of rivers is filled with low-frequency sounds like the babbling of water, so they can't communicate unless they have high-pitched voices. Cities are overrun with low-frequency humming from cars and such, but conversely, birds with high voices can communicate easily.

I see. So that's why their voices are high.

Between rural kingfishers and urban kingfishers, the urban ones definitely have higher voices. It's called urban acoustic ecology; birds with high-pitched calls are rapidly increasing in cities. For example, among wagtails, the White Wagtail is increasing significantly right now.

Birds like the White's Thrush wouldn't stand a chance.

That seems difficult. Their voices would become inaudible.

Among wagtails, the Japanese Wagtail makes a bit of a 'jay' sound, right? I think the reason White Wagtails are increasing so much in the city is that communication is easier for them.

White Wagtails are in convenience store parking lots now.

Rather, they've moved away from the river and are just normally around there. They find it too much trouble to fly, so they walk along the road (laughs).

Urban ecosystems have certainly entered a new phase. The destruction of urban water environments from the 1950s to the early 80s was horrific, and the components of the native ecosystem collapsed significantly once.

After that, as water quality gradually improved and various organisms returned, different groups of organisms adapted to those changes and settled in. It should take quite a while for that to stabilize, but we have definitely entered the next phase. I think a new ecosystem is emerging that ecologists have never seen before.

Rather than pitting the city against the countryside or nature and saying the city is bad, we should see the city as a place completely different from everywhere else, an environment where only those that have adapted can live. However, there aren't as many Japanese ecologists seriously doing urban ecology as you might think. Mr. Yanase might be a pioneer in that.

Also, what has clearly changed is that there are a lot of trees with oak wilt in Tokyo now. In the place where the jewel beetle was earlier, sawtooth oaks and konara oaks are being cut down due to oak wilt. When I counted the rings, the age was over 100 years. Meiji Jingu also has a lot of oak wilt, and the oldest konara oak had 110 rings. The seedlings planted when Meiji Jingu was established have now become giant trees and are dying.

The fact that there are many half-dead giant trees of the Fagaceae family aged 70 to 100 years in the city center is probably affecting the urban natural environment. I remember seeing a Japanese Pygmy Woodpecker for the first time with you at the Hiyoshi Campus, Mr. Kishi.

In Hiyoshi, one Japanese Pygmy Woodpecker was confirmed in 1985, it became a pair the following year, and they have been breeding ever since. In the case of Hiyoshi Mamushigaya, there was clearly a critical turning point around 1985. The trees became thick enough for the woodpeckers to excavate nests. The average size of konara oaks at that time was 10 to 15 centimeters. If there were some slightly larger ones around 20 centimeters, they could dig nests.

In 2000, Japanese Sparrowhawks arrived, which means the conifers had become giant trees and created a dense canopy of leaves where the hawks could build nests. Since around then, cities have really been changing all over.

Japanese Pygmy Woodpeckers certainly weren't around in the past. They increased suddenly. Will it be the same for Long-tailed Tits?

I saw young Long-tailed Tits at Senzokuike last year. Everyone came to take pictures.

They are cute, aren't they?

They were all lined up. Long-tailed Tits have become a common sight in several parks.

In the past, they were something you had to go somewhere specific to see, weren't they?

For Long-tailed Tits, the fact that moss has returned to the town is probably a factor. When they build nests—and this is true for Japanese White-eyes too—they use moss and spider silk, right? They can't build a nest with just leaves.

Also, they can't build them without bird feathers. I once picked up a Long-tailed Tit's nest.

The moss used as nesting material was glowing green, so I drew it, but eventually the surroundings started to crumble, so I disassembled the whole thing. There were many different types of feathers, including pigeon. There were also moorhen and crow, as well as Bamboo Partridge and pheasant. I think they were from birds taken by hawks. Anyway, all sorts of things were in there.

So, because the hawks returned, the Long-tailed Tits became able to build nests.

At the Hiyoshi Campus, the crow population, which was about 2,000, plummeted when the Japanese Sparrowhawks arrived. They engage in dogfights, but a single sparrowhawk can defeat five or six Large-billed Crows.

That's amazing. Even though they're so small.

When there were injured crows all over, Northern Goshawks first came to eat the crows. Surprisingly, Common Buzzards also came to eat the crows. You wouldn't think a buzzard would eat a crow, would you?

Everyone is watching closely (laughs).

It's truly an ecosystem.

They really are watching closely. Crows can never beat a Japanese Sparrowhawk. Their turning speed is different, so they just get kicked. They don't kill them, but they injure them.

And the injured ones get eaten by goshawks or buzzards.

Common Buzzards in the city center are always being harassed by crows, and their feathers are tattered.

Because their turning radius is completely different. Goshawks also have a large turning radius, so they hate fighting crows. Sparrowhawks have a small turning radius, but their mass is small, so if they get kicked by a crow, they get sent flying. Watching the fights between hawks and crows never gets boring.

It's interesting. I really like that sharp sense of tension in the air when a hawk appears.

First, it goes silent. Then the crows start making a huge racket.

Yes, you can tell when one has arrived. It happens sometimes even in the city center.

Rivers that look like urban ditches might be like steep canyons for living creatures. The things living there aren't sweetfish or landlocked salmon, but Neocaridina denticulata and red swamp crayfish, so there's no poetic sentiment, though.

Thunberg's meadowsweet is blooming now in dry places without water among urban buildings, right? Do you know where that plant is originally from? It's a tree that grows from crevices in rock walls at the furthest reaches of mountain streams in Ishikawa Prefecture, where water splashes up. However, it turned out to be a perfect fit for the environment between urban buildings.

Is that so? I didn't know that.

Things like that are happening more and more in the city; it's not a simple world. If you ask if nature has returned, the answer is no. A new urban-type ecosystem that no one has ever experienced before has been created, so we've reached an era where it's pointless to argue whether it's old-fashioned nature or not, or whether it's invasive.

To put it extremely, since global warming is already happening, the entire Earth is like a city. When thinking about the Earth's biodiversity as a whole, the model might actually be Tokyo, rather than the Kitakami Mountains or Ozegahara. By combining the mosaic-like occurrences here, we might be able to read the future of biodiversity in the urban world to come.

I see.

People involved in nature conservation in Japan can't keep up with this. They insist that there are primary nature, deep mountains, satoyama, and cities, and that protecting nature means restoring the ruined nature of the city to its original state. But something completely different has already been created. Even if you think about what the world of kingfishers that Mr. Yanase saw was originally, there is no answer anywhere.

A characteristic of Tokyo's topography is the series of small basins created by springs at the edges of plateaus. There are many small basin headwater topographies, and the most powerful people used to take the springs. Because it was the center of power, that nature was conversely preserved.

Topographically, these are places where it's easy for creatures to live, and while they seem like dots, the structure of the river basins actually remains surprisingly systematic. I think the city center is probably the easiest place to observe kingfishers right now.

That's true. The most amazing thing is their lack of wariness toward people. I wonder if they'll eventually start landing on people's hands (laughs). They seem like they'd come if you were holding a fish.