The Town Where Kingfishers Live

I also only started properly observing Tokyo's kingfishers 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 advantageous for kingfishers, and their numbers are growing. I believe we need to use the kingfisher as an opportunity to re-evaluate urban nature.

Since I couldn't go anywhere during COVID, I tried walking along River A, an urban river near my home in the city center that is 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. People thought they couldn't dig nesting burrows because of the concrete. So, I wasn't looking at it with the expectation of finding kingfishers.

Then one day in May, while I was walking, a local man 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 embankments of nearby green spaces.

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 come during the 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 goby (Gymnogobius castaneus). Because biodiversity in Tokyo's rivers is low, the kingfishers are forced to have a restricted diet.

Pure freshwater fish in city center rivers were once wiped out 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 'Dinner! Dinner!' (laughs).

Mullets swim fast, so they are difficult to catch. But the gobies move by clinging to the riverbed, so they can be caught very 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 introduced invasive species: Neocaridina 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. In the city center, quite a few stone moroko remain in ponds.

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 is that, unlike the diagrams of natural environments where kingfishers are usually found in field guides, they are breeding in rivers 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 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 all year round a long time ago. In the late 1950s, in the lowlands of the lower Tsurumi River, fragments of a waterway called the Nikaryo Canal remained here and there. In places where the vertical wooden stake revetments about 2 meters high were collapsing, there were large numbers of crayfish, 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 were not vertical but gentle, with silver grass and reeds growing. In that case, kingfishers couldn't build nests.

But now, in Tsunashima, Kohoku Ward, Yokohama City, which is in that same middle reach, kingfishers are there all year round. This is because dredging was done and the banks were made vertical. They are building nests in mud walls 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. In my area, there are irrigation ponds where they catch food, but there is no suitable soil nearby, so they go back and forth to nests quite far away.

Tokyo's kingfishers are living in a kind of high-rise apartment, eating Chinese food and hamburgers—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 Neocaridina shrimp. And right above them, there are Japanese rat snakes about a meter and a half long.

They must be eating kingfisher chicks sometimes. 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. I had been looking at the nature-rich Koajiro and the headwaters of the Tsurumi River with Mr. Kishi for nearly 40 years, so I hadn't really looked at the nature in the city center, even though it was close by. But when I look at my neighborhood, it's incredibly interesting (laughs).

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 frequently come to Shinobashi 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, and those living there are making business trips.

In the old days, they probably went to goldfish shops and ate 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 an image of kingfishers eating sweetfish in clear streams, but that might be a myth. There are probably some like that, though.

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

The living environment, or rather the effort required, is really 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, one could say they are "thriving because it's the city." They have become that kind of urban bird.

Tokyo's urban rivers are very clean now because the sewage system has developed. However, because most living things were once wiped out, 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 eating plenty of juvenile bluegill, which are breeding in large numbers in the pond.

But there are people who say that because kingfishers are supposed to eat Japanese fish, kingfishers that eat foreign fish or shrimp are not truly Japanese.

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

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

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

That's true.

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

These fairly large springs that pop up 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.

Along the Kanda River, for example, you have Chinzanso or the Higo-Hosokawa Garden 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. Essentially, 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. 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 live in high-end residential areas like the Shirokanedai 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 are also 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. After that, the rivers gradually became cleaner, and some of the birds from the springs started living in "apartments" 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 had been 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 a new nesting burrow 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 hole they used last year again the following year, but they used different holes in the spring and summer. In other rivers, they change every year.

So, they have a rotation.

I think so. Last year, when I spent a day following them, a pair spent all day from morning to night looking for holes over a stretch of about a kilometer and a half. Moreover, there are cases where they prepare another hole as a trap and pretend to be raising young there to deceive natural enemies.

I see. It's like a Northern Goshawk.

In my area, there are holes in the bumpy mud cliffs. When they make them, they charge at the mud cliff, and both the males and females chirp very noisily.

They have a high-pitched voice, like 'kyo-kyo-kyo-kyo'.

That's exactly it. The male works on making the hole, and the female chirps away at something.

The female eggs him on. They line up on the tip of a branch, and she tells him to go for it. Then the male charges. The female cheers him on, but if she loses interest, she just flies off somewhere.

Actually, even though there are muddy spots near my house, they seem to go out of their way to use drainage holes. There are two pairs in the regulating pond; one has a dirt burrow, and the other seems to be using a drainage hole.

My parents' home is in Hamamatsu, and it's exactly the same. There are dirt walls along the river where they could dig holes, but 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 pale chub fry right under the nest, so they can catch them easily.

It depends on how the area behind the drainage hole is constructed. There is a 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. It's possible that 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 at that depth, they manage to dive in and catch food properly.

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

They also hover at low altitudes and catch prey quickly; they are doing very skillful things.

They are quite skilled, or rather, they have a proper way of doing things.

They probably change their diving style depending on the location. They have truly become urban birds.

I think their genetic habits will change over several thousand years.

Looking at Ms. Otaguro's book "Birds (Hakken Zukan Plus)" (GAKKEN, supervised by Keisuke Ueda), it was very fun to see that among all the 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 (woodlands near human settlements).

I asked them to add that. I said, "Let's include the kingfisher."

The satoyama side has an orthodox kingfisher feel. It's at the edge of a rice field.

My place is like this.

What's interesting is that it's not just kingfishers; raptors are 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 a lot of food now.

Because there are pigeons.

Pigeons and Rose-ringed Parakeets.

There are many at Tokyo Tech (Ookayama Campus), aren't there?

The descendants of the birds that originally settled on the Ookayama Campus in the late 1960s grew to about 3,000 by 2015. The parakeets would cluster in the ginkgo trees and be very 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 earlier (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 I never saw a Northern Goshawk flying over the Tsurumi River until around 1990. They suddenly started increasing in the 90s, eating rock doves and little egrets.

One factor is that around that time, coniferous trees like cedar and cypress planted after the war reached a diameter of 30 or 40 centimeters, making it possible to build nests. Also, rock doves increased tremendously. And little egrets and black-crowned night herons also increased, so 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 also Eurasian Sparrowhawks.

I think the Eurasian Sparrowhawks were a bit earlier. Common Buzzards are occasionally seen in the back of Machida.

They were in Shinjuku Gyoen too.

Common Buzzards can be seen almost anywhere. I think both the Japanese Sparrowhawk and the Northern Goshawk have become urban birds. Common Kestrels are building nests in groups of two or three pairs 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.

Birds like ducks and Little Grebes that swim on the water have completely different circumstances. 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 pollution for each environment. For example, around Tsunashima on the Tsurumi River, the number of species of migratory ducks and grebes was highest around 1990, but 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 household disposers crushed vegetables, all sorts of ducks like Northern Pintails and gulls would gather where the tributaries met the main river to look for those vegetable scraps when it rained, but now there's nothing. The only ones that come are Eurasian Coots. I'm not sure why they 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, not only can kingfishers return, but valuable creatures from long ago actually remain in quite large numbers.

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 appear in the summer.

Since they aren't creatures that can fly long distances, the greenery at the headwaters of small river 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 returning to the river after they grow up, but that doesn't seem to matter at all.

We need to seriously investigate the ebony jewelwing. In the Tsurumi River, they once went extinct from the mouth to the headwaters, but they suddenly started increasing 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-tipped damselflies appeared in the pond in my garden. I think they were probably attached to the water hyacinth I bought at a home improvement store. 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 springs of green spaces in the city center. There are plenty of river snails in a park just three minutes from a station on the Yamanote Line. It was originally a place famous for fireflies. You also see Japanese freshwater crabs normally. Surprisingly, nature remains in the center of Tokyo, and there is more depth to the biodiversity than everyone thinks.

Depending on the opportunity, they might make a comeback from there.

Dragonflies and birds especially 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 urban rivers are the native freshwater fish and shrimp that were originally there. In urban rivers, even if you can see kingfishers, you rarely see the silver crucian carp, which was the most common species 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 air. 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 also 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 feathers that 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 even if you look 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 having pigment; 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 it's a kingfisher feather, would you?

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

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

Oriental Greenfinches are hard to come by in their whole form, so I was having trouble when I was making the book. Then, a neighbor brought me a male Oriental Greenfinch, saying they found a beautiful bird that had died. I thought it was a gift from God.

The feathers of a Kingfisher grow quite densely, don't they? Since you can only see the tips.

The color itself is a beautiful blue. Is it difficult to paint Kingfishers?

The color is indeed difficult.

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

Having observed birds for many years, have you noticed anything that has changed about birds recently?

The number of Ruddy-breasted Crakes has increased around my house. It used to be said that they didn't overwinter in Ibaraki, but they stay all through the winter now, and there's a significant population.

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, in the grass along the river near my parents' house where Kingfishers used to be, I heard a strange voice and it turned out to be a Ruddy-breasted Crake. They have quite a strange voice, don't they?

That's right. Their alarm call is close to 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.

Kingfishers in the city are fine even if there are construction vehicles right next to them. They don't mind the noise at all.

Originally, the world of rivers and the sound of murmuring streams are filled with low-frequency sounds, so communication is impossible unless you use high-pitched sounds. Cities are rife with low-frequency humming from cars and such, but conversely, birds with high-pitched voices can communicate easily.

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

Between a country Kingfisher and a city Kingfisher, the city one must definitely have a higher voice. 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 won't make it, then.

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 because communication is easier for them.

White Wagtails are in convenience store parking lots now.

They've moved away from rivers and are just around everywhere. They even walk on the road because they're too lazy to fly (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, water quality improved steadily, and as various organisms returned, different groups of organisms corresponding to that change began to settle. It should take quite a while for that to stabilize, but we have definitely entered the next phase. I think a new ecosystem, the likes of which ecologists have never seen before, is emerging.

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 anywhere else, an environment where only those that have adapted can live. However, there aren't many Japanese ecologists yet who are seriously doing urban ecology. Mr. Yanase might be a pioneer in that.

Also, what has clearly changed is that there are now many trees suffering from oak wilt in Tokyo. In the area where the jewel beetles were earlier, sawtooth oaks and konara oaks are being felled due to oak wilt. When I counted the rings, the trees were over 100 years old. 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 right now 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.

At Hiyoshi, one Japanese Pygmy Woodpecker was confirmed in 1985, they became a pair the following year, and they have been breeding there 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 a nest.

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

Japanese Pygmy Woodpeckers certainly weren't around in the past. They increased suddenly. I wonder if the same will happen 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, you had to go somewhere specific to see them.

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've picked up a Long-tailed Tit's nest before.

The moss used as nesting material was glowing green, and I painted it, but eventually the surroundings started to crumble, so I disassembled the whole thing. There were many different kinds of feathers, including pigeon feathers. There were also feathers from Moorhens, Crows, Bamboo Partridges, and Pheasants. I think they were from birds killed by hawks. Anyway, there were all sorts of things 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 aerial combat, and a single Japanese Sparrowhawk can take down five or six Large-billed Crows.

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

When there were injured crows all over the place, first Northern Goshawks came to eat the crows. Surprisingly, Common Buzzards also came to eat the crows. You wouldn't think a Common 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; they injure them.

And the injured ones get eaten by Northern Goshawks and Common 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. Northern Goshawks also have a large turning radius, so they hate fighting crows. Eurasian 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.

That'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 fuss.

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. Although there's no sentimentality because instead of Sweetfish or Land-locked Salmon, there are Chinese Grass Shrimp and Red Swamp Crayfish.

Thunberg's Meadowsweet is blooming now in dry, waterless places among city buildings. Do you know where that plant is originally from? It's a tree that grows from crevices in rocks, where water splashes, deep in the mountain streams of Ishikawa Prefecture. However, that environment turned out to be a perfect match for the spaces between city buildings.

Is that so? I didn't know that.

Such things are happening more and more in cities, and it's not a simple world. It's not that nature has returned. A new urban ecosystem that no one has ever experienced 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 considering the global biodiversity as a whole, the model might not be the Kitakami Mountains or Ozegahara, but actually Tokyo. By combining the mosaic-like occurrences here, we might be able to read the future of biodiversity in the urban world of tomorrow.

I see.

People involved in nature conservation in Japan can't keep up with this area. 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 watersheds created by springs at the edges of plateaus. There are many small watershed headwater topographies, and the most powerful people used to take the springs. Because it was the center of power, that nature was conversely preserved.

It's a place where it's topographically easy for creatures to live, and while they seem like isolated spots, 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 become tame enough to sit on your hand (laughs). They'd probably come to you if you had a fish.