You’ll find squirrels all over Japan, especially on Honshū, Shikoku, and Kyūshū. The native Japanese squirrel hangs out in forests and parks.
If you wander into the right woodlands, you might spot small reddish-gray tree squirrels. Some places even let you get surprisingly close to them.
This post covers the squirrel species you’ll find in Japan, where they hide, how they behave, and what people are doing to protect them.
Curious about where to actually see them or why they matter to Japan’s forests? Stick around—let’s break it down.
Squirrel Species in Japan
Japan has a few native tree and flying squirrels, plus some non-native species that showed up later. Each one looks and acts a bit differently, and they all have their own spots on the islands.
Japanese Squirrel (Sciurus lis)
You’ll mostly see the Japanese squirrel, Sciurus lis, on Honshu and Shikoku. It likes mixed broadleaf forests and snacks on seeds, nuts (it really loves Japanese walnut), buds, and fruits.
You might catch it foraging up in the trees or sometimes down on the ground.
Adults weigh about 250–310 grams and have grayish fur with a big bushy tail. They tend to live alone and stick to daytime activity, moving around based on where the food is.
Over the last century, numbers have dropped in parts of western Honshu, and they’ve been gone from Kyushu for about 100 years. Local conservation efforts have become pretty important.
You can learn more about their habits and where they live at the Japanese squirrel entry.
Japanese Giant Flying Squirrel (Petaurista leucogenys)
The Japanese giant flying squirrel, Petaurista leucogenys, is, well, giant and only comes out at night. It glides between tall trees using a stretchy skin flap called a patagium.
You’ll usually notice them at dusk or after dark, especially in mature forests.
They eat leaves, fruits, seeds, and bark. Adults can get over 40 cm long (not counting the tail) and weigh a lot more than tree squirrels.
These squirrels really need big, connected trees for gliding and nesting, so when forests get chopped up, they’re in trouble.
They only live in Japan and depend on forested areas with tall trees.
Japanese Dwarf Flying Squirrel (Pteromys momonga)
The Japanese dwarf flying squirrel, Pteromys momonga, is tiny and also sticks to the night. It glides short distances and builds nests in tree holes or dense branches.
You’ll find it in temperate forests on Honshu and Kyushu (and a related subspecies up in Hokkaido).
It eats seeds, buds, and leaves. Adults are much smaller than the giant flying squirrel, which makes them tough to spot.
Since they’re quiet and active at night, you’ll probably only catch a glimpse at dusk.
They rely on tree cavities, so keeping old trees around is key for their survival.
Non-Native and Other Squirrel Species
Japan has some non-native squirrels too. A few escaped or got released from captivity, like Pallas’s squirrel (Callosciurus erythraeus), the Eurasian red squirrel (Sciurus vulgaris), and the Siberian chipmunk (Tamias sibiricus).
These newcomers have set up shop in several regions and sometimes compete with native squirrels or damage trees.
The government lists some as invasive and has removed them where they’ve caused problems.
If you see a squirrel you don’t recognize, local records and management reports can help you figure out if it’s native or not. There’s more info in research on the distribution and management of non-native squirrels in Japan.
Habitats, Behavior, and Conservation
Japanese squirrels stick mostly to forests on Honshū and Shikoku. They used to live on Kyūshū too.
They like mixed forests and pine woods, eat mostly nuts and seeds, and face threats from shrinking and broken-up habitats.
Distribution Across Japanese Islands
You’ll find the Japanese squirrel (Sciurus lis) mainly on Honshū and Shikoku. Kyūshū used to have them, but their numbers there have dropped a lot and they might be gone from some parts.
They live in lowland mixed forests and higher pine forests, especially in places with mature trees that drop nuts and seeds.
Small, broken-up forests make it hard for them to find food and nesting spots, so their groups get cut off from each other.
Where forests stay connected, the squirrels do better. In western Honshū, populations are tiny and scattered. Some prefectures even list them as regionally endangered.
If you want more details on their distribution and threats, check out this review: Frontiers in Ecology and Evolution.
Physical Appearance and Adaptations
You can spot a Japanese squirrel by its medium size, bushy tail, and rounded body. Their fur goes from gray-brown to reddish-brown, depending on where and when you see them.
Some get faint ear tufts in winter, but they’re not as obvious as those on Eurasian squirrels.
Their sharp claws help them climb trees, and their long tail helps with balance and staying warm.
They’ve got strong jaws and teeth for cracking tough nuts like Japanese walnut and acorns. Their eyesight and hearing help them stay alert during the day and escape predators fast.
Diet and Feeding Habits
Japanese squirrels mostly eat nuts and seeds—acorns and Japanese walnut are favorites when they’re around.
They also munch on young leaves, buds, fungi, and sometimes insects.
You’ll see them stash food in tree holes or bury it in the soil for winter. Not every seed gets eaten, so they help new trees grow too.
Their diet changes with the seasons: more buds and insects in spring, a frenzy of nut gathering in autumn.
They’re mainly herbivores but will eat whatever’s available. If there aren’t enough seeds, they switch to fungi or green plants. This flexibility helps them survive even when forests change.
Lifestyle, Social Structure, and Reproduction
Japanese squirrels spend their days out and about. They’re mostly solitary, so you’ll usually catch one foraging alone, fiercely guarding a small patch of forest where it keeps its food and nest.
Breeding usually picks up in late winter and goes through spring. The female carries her young for about 38 to 45 days. She’ll usually have one or two litters a year, with two to five babies in each.
The young hang out in the nest for a few weeks before they finally poke their heads out. If you hear territorial calls or spot a squirrel flicking its tail, that’s probably a sign of a social skirmish.
Their conservation status really depends on where you look. Habitat loss, fragmentation, and forest degradation hit their breeding hard and shrink the areas they can claim as home.
If we want them to stick around, we need to protect bigger chunks of forest and make sure these patches stay connected. That’s what gives them a real shot at surviving and raising the next generation.
