1. The Golden Eagle: A Mountain Eagle That Nests on Cliffs
The representative eagle of the mountains is the Golden Eagle (Inuwashi). According to the Ministry of the Environment, it lives mainly in Hokkaido, Tohoku, Chubu, and the Sea of Japan side of Chugoku, with very few in Shikoku and Kyushu. It stays in mountainous areas year-round as a pair [1]. While it lives in Japan all year, globally it is found across Eurasia, North America, and northern Africa [3].
They build their nests on rock ledges of steep cliffs or high tree branches. These nests are made by combining branches and dead grass [3]. Their main food includes Japanese hares, pheasants, and snakes. They also catch serows, young deer, and martens [1].
Even though they eat mountain animals, the place where they nest is not always the same as where they hunt. So, where do they actually hunt?
2. Why Dense Forests Are a Problem for the Golden Eagle
The Golden Eagle hunts in open areas that look like grasslands [2]. This is one answer to why they choose certain places. A cliff for nesting is not enough; they need open spaces nearby to catch prey.
The area they use is quite large. The home range for a pair is 20–250 km² (7.7–96.5 sq miles), with an average of 60 km² (23.1 sq miles). This includes both their nest and hunting grounds [1]. To picture this, 60 km² is a square about 7.7 km (4.8 miles) on each side.
This means that if mountain maintenance decreases, it affects the eagle’s life. The Ministry of the Environment lists the lack of care for forests and grasslands as a factor in their decline. This reduces suitable hunting grounds and the habitats of prey animals [1]. Growing forests is not bad in itself, but for this bird, it means losing hunting space.
So, mountain eagles look for open spaces. But what do sea eagles look for?
3. White-tailed Eagles and Steller's Sea Eagles Gather on Hokkaido's Coasts in Winter
Looking north, the eagle’s habitat changes completely. In winter, White-tailed Eagles and Steller’s Sea Eagles gather near coasts and lakes in Hokkaido.
The White-tailed Eagle has some individuals that breed and stay in Hokkaido all year, while others migrate from Russia for the winter. They build nests on large trees along coasts, lakes, and rivers. About 170 nesting sites have been confirmed in Hokkaido [4]. They eat sea birds and fish like pollock, and also scavenge leftover fish from fishing boats [4]. Their nests are made of branches on tall trees or cliffs [5].
The Steller’s Sea Eagle breeds in eastern Russia, such as the Kamchatka Peninsula, and migrates to Hokkaido for winter. It mainly eats salmon, pink salmon, and pollock. Its wingspan is 220–250 cm (86.6–98.4 inches) [6].
If fish are their food, then water edges become their hunting grounds. Just as mountain eagles need open grasslands, sea eagles need waters where fish live.
Now, what about the eagle on the southern islands?
4. The Crested Serpent Eagle of the Yaeyama Islands Waits on Utility Poles
The Crested Serpent Eagle (Kanmuriwashi) is found only in the Yaeyama Islands of Japan. It lives year-round on Ishigaki and Iriomote islands, and has also been confirmed on Yonaguni [7].
During breeding season, they build nests in broadleaf forests in mountains near the coast. At other times, they are seen near rice paddies, fallow fields, forests near pastures, and around utility poles along roads [7].
They hunt snakes, frogs, and freshwater crabs. They use an "ambush" style of hunting: they sit on utility poles or dead trees and wait for prey to come close [7]. Unlike the Golden Eagle, which needs wide grasslands, rice fields and perches are part of this eagle’s hunting ground.
It seems that "what they eat" and "how they hunt" determine where they live. These places may be part of their hunting grounds: mountains need open areas; coasts need waters with fish; southern islands need fields where prey appears and perches to wait on.
5. What Makes an Eagle an Eagle? The Eagle–Hawk Line and Conservation
The line between "washi" (eagle) and "taka" (hawk) is actually vague. Dictionaries say large species are generally called eagles, while small ones are hawks. But taxonomically, there is no strict distinction. Some large birds are named with "taka," like the Mountain Hawk-Eagle (Kumataka) [9]. So, a bird about 55 cm (21.6 inches) long can still be called an eagle.
These eagles face environmental changes. The estimated population of Golden Eagles was about 500 individuals in 2022 (Reiwa 4), with a national average breeding success rate of 17.4% [1]. The Crested Serpent Eagle is a National Special Natural Monument and listed as endangered by the Ministry of the Environment [7]. Reports suggest there are about 100 individuals on Ishigaki and Iriomote islands combined, though the survey year is unknown [7].
People are trying to create hunting grounds. In the Akaya Project in Gunma Prefecture, starting in 2014, they tested cutting down artificial forests to create open spaces. A report said that after two years, Golden Eagles recognized about 2 hectares (5 acres) of cut land as a place to hunt [2]. This is about the size of three soccer fields. However, this was an interim report, so effectiveness is not fully proven.
In the Nazo district of Ishigaki City, road accidents involving Crested Serpent Eagles are a problem. There is a plan to test whether biotopes can attract eagles as feeding grounds [8].
6. How Place and Hunting Style Connect to Where Eagles Live
Comparing these four eagles suggests that "what they eat" and "how they hunt" are deeply linked to where they live. However, this is an interpretation from comparing sources, not a direct statement in all of them.
Try this: Use string and a ruler to feel the size. Cut string to 220–250 cm (86.6–98.4 inches) and lay it on the floor; this is the wingspan of a Steller’s Sea Eagle [6]. Measure 55 cm (21.6 inches) with a ruler; this is the body length of a Crested Serpent Eagle [7]. Note that wingspan and body length are measured differently, so this is just a rough comparison.
If you see birds in a nearby park or by a river, watch where they perch and what they look for. Birds waiting on poles or trees, and birds walking along water edges, might show a link between their location and hunting style.
For further reading, the Ministry of the Environment’s page on Golden Eagles [1] and the Forestry Agency’s Okinawa Forest Management Office page on Crested Serpent Eagles [7] provide short summaries in Japanese.