Japan's Natural History: Blakiston's Fish Owl
Blakiston's Fish Owl Kotan Koru Kamui: The God of the Village
In folklore, owls are often considered to be wise, even gentle, thus adding to their general popularity, although in times past the calling of an owl was thought to indicate that death was near for the listener or a member of their family.
Owls do in fact signify death, not for humans, but for their prey. They are efficient and deadly hunters, searching out their food by sight and sound during the night, when they take small mammals (including pests to man such as rats and mice), reptiles, birds, large invertebrates, and, in a few rare species, even fish.
In the north of Japan, beyond the important biogeographical divide known as Blakiston's Line, lives one of those rare species, appropriately known as Blakiston's Fish Owl, or Shima Fukurou.
This enormous owl is rare, poorly known and little studied. Its main range takes in the mountains and rivers of the maritime provinces of eastern Russia (and perhaps still extreme northeast China), and Sakhalin, the southern Kurile Islands, and Japan's northernmost island of Hokkaido.
Until the mid 19th century, before Hokkaido was officially settled by Japan, this magnificent owl occurred throughout the island then known as Ezo. Wherever there were mature forests and shallow rivers with plentiful fish, this giant of owldom could make itself a home; but since then the forests have shrunk, diminished as forestry, farming and urbanisation have spread, and they continue to lose ground.
In the transition from the frontier land of Ezo to the developed island that Hokkaido has become, rivers have been straightened, some turned into little more than concrete-lined canals, fish populations have declined and now the river banks are further disturbed and fished by sports fishermen. Today, Japan's largest and most dramatic owl is very rare indeed - making it one of the rarest breeding birds in the country, and given its restricted range, one of the rarest birds in the world.
A larger than life-size fish owl greets travelers arriving at Hokkaido's Kushiro Airport. They typically eat fish very much smaller in proportion than this one!
The plight of the Japanese Crested Ibis, the Toki, was much in the news during the 1980s as it neared extinction, and is again now during the 2010s, as captive breeding and re-introduction appear poised to save it from that terminal fate. Yet little media attention has been given to the fate of another endangered species, particularly the eponymous fish owl. Surely Shima Fukurou is worthy of attention, after all it is not merely a stunning example of adaptation to an extreme environment, not only a rare and endangered species; it is a God!
To the indigenous Ainu people of Hokkaido, the fish owl was revered as a Kamui, a god or a spirit. Of a pantheon of deities significant in the ancient Ainu life-style, the fish owl was the god they were closest to, literally, for it was to them Kotan Koru Kamui - the god that protected the village.
In centuries past both Ainu and owls lived together in the same areas alongside fish-rich rivers. Ainu settlements were typically at the confluence of rivers, or on low escarpments over-looking rivers or their mouths, and typically where there was mature forest providing ideal hunting grounds for fish and game.
These were the very same features of the local environment that the owls depended on, and so the lives of fish owl and Ainu became entwined. Today, despite its rarity the fish owl still features most prominently in the designs of Ainu wood carvings.
Blakiston's Fish Owl with typical, small fish prey. They usually consume prey head first.
Fish owls are sit and wait predators, for them hunting requires interminable patience.
The large piscivorous owls in the genus Ketupa are extraordinary. They have become adapted to a diet of fish, which they catch with their feet. Their feet are enormous, their talons long and sharp and the soles of their toes are covered with rough scales - all adaptations for grasping and carrying slippery fish, which they typically carry off from the site where they caught it, to devour on the branch of a forest tree.
Since fish are unable to hear sounds above water, it is said that there has been less necessity for silent flight in this group of nocturnal birds than amongst others, and it is said that their wings make an audible swishing noise, yet to my ears their wings are as close to silent as is the passing of a ghost.
On huge, broad wings they achieve plentiful lift allowing them to glide through the forest at low speed and to achieve the lift they need when taking off, laden with a fish, from the water's margin. Yet despite its waterside habits, this is not a water bird, and it does not have waterproof feathers, as ducks, geese and swans do.
Although their normal preening oil enables them to shrug off splashes, were they do land in deep water, their loose, soft plumage would quickly become waterlogged, so they avoid the deeper flows of water, choosing instead to fish in the shallow margins and shoals of rivers and in shallow swampy marshes.
There, at night, they stand in the shallows, or on a fallen branch, or a rock, at the waterside, waiting, waiting and watching. Their eyesight is extraordinary. Unlike most owls, able to hunt their prey by sight and sound, the fact that the bulk of their prey lives in noisy flowing water means they must rely on sight almost entirely; yet they hunt at night.
I have watched them year round, but my strongest memories are of standing on the snow-coated ice of a frozen river in east Hokkaido, feeling the crunch of the ice lifting on the slow-rising tide and aware of the temperature plummeting as darkness falls, and straining my ears for the first calls.
Within an hour of dusk is when they are most likely to commence their duet and that sonorous sound would raise goose-bumps on my flesh - were any of it exposed. The biting cold of temperatures well below freezing chill the extremities first then eat at one's core temperature, standing still is the hardest thing to do, but eventually the owls call, they fly out from their roost, perch high in silhouette and their throats bulge noticeably as they boom out their calls.
On bright moonlit or starry nights I can just make out their large lumpen shapes silhouetted in riverside trees, or hunkered beside the river; I can see nothing of what lies beneath the water's surface. Yet in their waiting they are also observing; time passes, they watch then suddenly they half fly, half pounce, grasping with their feet, their wings raised casting shadow and once again they catch a fish I could never have even seen.
The bare toes, massive roughened pads and long claws are the marks of a consummate predator.
Blakiston's Fish Owl is so rare because of three basic requirements of its lifestyle. It lives in the north, eats mainly fish and nests in large holes in trees. Freezing winter weather in this god's northern realm seals many fish away under protective ice, preventing the owls from fishing in the easy-to-fish shallows. They must turn instead to fast-moving water and river mouths, even coasts, where fishing is more difficult. They even turn to other food, taking voles, small birds, and flying squirrels, and early emerging frogs on occasion.
In order to breed, fish owls need old trees, very large and very old trees, with holes large enough for the female to enter and turn around in. Such sites are naturally uncommon; such cavities are naturally limited resources and are only found in the oldest and largest of the trees.
Yet there is the added factor that many forests are gtidied-uph, old trees are cut down, so in reality such sites are now very rare. The older the tree the greater the likelihood of it having a suitable hole for nesting, and the greater the likelihood that it will be felled by storm or forester.
The owls are a Natural Monument (a government designation), but absurdly the very habitat they require to survive isn't fully protected, even though much of it belongs to the government's own forestry agency. Are they destined to go the same way as the Toki, the victims of environmental destruction and red tape?
Arguably the largest owl in the world, Blakiston's Fish Owl is also one of the rarest, here one sits beside a mountain river in east Hokkaido patiently searching for prey.
A breeding pair of Blakiston's Fish Owls will stay together throughout the year in their territory, which they retain for many years. They call each night and at every season. Their deep goo-oo; huh is actually a duet, the male contributing the first double part and the female adding her conclusion.
The deep sounds reverberate through their forest habitat and would have been the nightly accompaniment as the inhabitants of Ainu villages settled down to sleep. Each pair called to maintain their mutual bond and to mark out their territory from those of other pairs along the same river systems, and each pair was resident throughout its life.
Only the young birds leave and wander from the area of their birth. In Ezo this owl was common and widespread, but in Hokkaido today fish owl pairs have become so scattered now that it is doubtful whether any pairs live close enough together to hear each other. Their lives revolve around their nesting site, they roost nearby and fish in the nearest rivers; they have lost their neighbours - both owl and Ainu.
Shima Fukurou is the largest owl living in Japan, at more than seventy centimetres from head to tail it is larger than most geese, and as large as a White-tailed Sea Eagle. It sits very upright presenting an unusual tapering teardrop shape. Its head is broad and low, its shoulders too are broad and the tail is very short and rounded. It has large loose ear tufts, which blow about in the breeze and its eyes are a striking yellow. The plumage is a varied mixture of browns and the feathers of the underparts have arrow-like markings.
Were the ancient beliefs true, that an owl's call presages death, then I would have died many times over. To be out at night in the forest, perhaps on a crisp winter's sky speckled with diamond sharp stars overhead, or on a muggy summer's night with insects buzzing, and to listen to the sounds of the owls whether Ural, Brown Hawk, Oriental Scops or Blakiston's Fish Owl, is to me being party to a magical experience.
When I take others out to listen and watch for owls it is not to hasten their demise, but to add a dimension to their experience of nature. A sighting of a fish owl pair in their natural habitat as they emerge from their roost, commence calling and head off into the night to hunt, is one of the most moving wildlife experiences possible; a brush with the gods.
Fish owls breed early in the year, laying during February or March and raising their chicks during the early summer in May. On their northern breeding grounds the deep layer of winter snow melts slowly and steadily during April and early May flooding lowlands, spreading and forming pools and swamps where frogs abound, at such sites I have seen fish owls running crazily back and forth, shambling, as if dressed in a loose feather cape and baggy trousers, as they chase and catch and swallow frog after frog.
This is their season of plenty and frogs provide an important boost for them in the spring when they have young in the nest. Once May ends their chicks will be large enough to emerge from the nest adding their prolonged, demanding psheuw calls to the sonorous duet of their parents.
On and on they call, insatiably, night and day, demanding that their parents bring ever more food. While their parents are forced to hunt through the night and even in to daylight during the short days of summer, the youngsters merely sit, great brown shapes on branches amidst the dense greenery of the summer forest, awaiting the arrival of more food.
The baleful stare of a roosting fish owl is disconcerting.
Summer or winter, Blakiston's Fish Owls roost during the day in relatively open situations. They have little to fear - they are one of the top predators of their northern range.
The young fish owls will remain in their natal territory for a year or more, slowly developing their own hunting skills under the watchful gaze of their deified parents. Perhaps it is their own wanderlust that draws them away, or perhaps the reproductive restlessness of their parents that drives them away, nevertheless eventually they move on in search of their own section of forest and river to live in, leaving their parents to raise another brood.
Raising broods was the issue that was most limiting the fish owls of Hokkaido when I first came on the scene in the early 1980s. It was clear then, thanks to pioneering research by Sumio Yamamoto, that fish owls were in trouble and that help and intervention were necessary to save them. Just three decades ago I would have predicted extinction for this bird in Japan within 25 years or so, nevertheless it has achieved a tenuous thread hold on life and there is something of a reprieve.
Research in the late 1970s and early 1980 showed that Hokkaido's Blakiston's Fish Owls were critically limited by the almost complete absence of nesting holes. The world's largest owl was being ousted by the steady loss, not merely of its lowland forested riverside habitat, but more rapidly by the specific loss of the very old hole-containing trees it needed, in which it nested. These old trees had been selectively logged or were being systematically tidied out of forestry areas and being steadily destroyed during winter storms, so that they were disappearing at a much faster rate than that at which they were developing.
By the late 1970s and early 1980s the situation was desperate. It seemed that Blakiston's Fish Owl pairs had almost no natural nesting sites left and so began a desperate effort to supply giant nest boxes for the remaining territories of this giant owl, an effort in which I was able to lend a hand. That project has been expanded over the years, and become official, the old wooden boxes have been replaced with lighter, high tech fibre-reinforced-plastic boxes, and some of them are now monitored by live-feed video cameras.
Many of the rivers in their range freeze over in winter making fish inaccessible forcing Blakiston's Fish Owls to look elsewhere and for different prey.
Just about all of the remaining pairs of the owls have adopted their high-rise artificial homes and some pairs have bred successfully year after year in them. That alone was cause for rejoicing in the early years of the project, but the fear persisted that the remaining offspring were so scattered in the isolated patches of forest that they would never find each other.
However, there the use of coloured leg bands helped to prove that young birds were moving out from their natal territories and not only finding each other but also setting up home together.
The author with an early prototype Blakiston's Fish Owl nest box, obtains a fish owl's view from a tree still far too young to have a suitable natural nesting cavity.
Of course, it hasn't all been plain sailing. There have been failures, when eggs have failed to hatch, or chicks have been predated, and there have been accidents, far too many accidents. These are slow flying, low flying birds, and many of their riverine habitats are crossed by road bridges, placing them at risk of impact with traffic.
Some of the new generations raised in nest boxes over the last few years have met their fate on the roads, others against wires, although others, thankfully, continue to survive and are now paired in the wild, but the continued loss of birds through accident and injury has meant that despite the best conservation efforts there is barely a recovery in numbers.
Nearly thirty years on, I can report considerable success of a kind; although numbers have not grown noticeably, the population seems to have been saved from its slow and inexorable decline towards extinction.
Invasive, even destructive, photography of the species at the nest seems to be on the decline, or to have disappeared entirely and even some of the injured birds have found their way back into the hands of one particular person dedicated to their protection and survival.
His successes have included the arrival of a free-living wild male, which was attracted to a young female that was being rehabilitated. I was there when the wall of her giant forest aviary was raised for the first time and at last the male and female met face to face without netting between them.
They began feeding together and looked as if they might pair and settle to nest in the now open aviary, if successes like that continue and translocation of pairs becomes possible then in the future we may see fish owls re-introduced into lost parts of their ancient realm.
Having spotted a fish, this Blakiston's Fish Owl is all concentration as it picks its moment to pounce.
Perhaps one day the deep resonant calls of a pair of Blakiston's Fish Owls will be booming out once more through the forest and along a river in an ancient territory vacant for the best part of a century.
With the return of Kotan Koru Kamui to the ancient forests, perhaps the spirits of the place will change for the better too and perhaps this will be the start of a new approach to nature in Japan, the re-establishment of an ancient right - to life!
Its only in young owls, before the head is fully feathered, that the true size of the massive bill is visible. This downy fledgling Blakiston's Fish Owl already has the bright yellow eyes typical of the species.
Text and Photographs: Mark Brazil
A writer, naturalist and wildlife guide, Mark spends half of each year travelling in search of wildlife and the other half writing about it from his base in Hokkaido.
Born and educated in England and Scotland, Mark spent more than ten years involved in the making of natural history documentaries for television, and nine years as a professor of biodiversity of conservation at Rakuno Gakuen University near Sapporo.
He began contributing his column, Wild Watch, to The Japan Times newspaper in April 1982, and has been writing about natural history and travel ever since.
His latest book, a field guide, Birds of East Asia, was published to considerable acclaim in 2009, by A&C Black and Princeton University Press.
You can learn more about Mark and his work via his website: www.japannatureguides.com