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Wednesday, Nov. 15, 2000

WILD WATCH

ANCIENT SURVIVORS

The secretive rabbits of Amami


Hunting rabbits is something I have only ever done on one island. When I say hunting, I don't mean with a gun; I mean armed with a spotlight, binoculars and notebook. The rabbits I hunt stay alive. That's rather crucial, because I am talking about the rabbits to be found marooned on an isolated island in the Nansei Islands. They have survived the millennia thus far in the absence of hunters of the more predatory kind.

The nocturnal habits of the Amami black rabbit have shrouded it in mystery.

Isolation on a remote island is a blessing. Typically, large mammalian predators don't reach such places, thus life is one whole step easier for the smaller species that live there which otherwise might expend time and energy devising ways to avoid being eaten. Easier, that is, until humans come along and complicate matters by converting habitat and introducing all sorts of aliens that compete and even predate the indigenous wildlife.

My early visits to Amami Island were to tease out the identification features of the Amami woodcock, a little-known bird endemic to the Nansei Islands. However, while searching for that nocturnal forest-dwelling bird, a kind of shorebird adapted to probing for food in the soil of the forest floor, I also met many of the other creatures of the Amami night, such as the Ryukyu Scops owl and various extraordinary frogs, and, every now and then, I was lucky enough to encounter the dark bulk of the Amami black rabbit. On subsequent visits I put more effort into observing the rabbits -- the woodcocks were, relatively speaking, easier to find.

The Amami black rabbit, subject of a new photographic book by Futoshi Hamada, is no denizen of open grassland, meadow or parkland, nor does it feature in any Beatrix Potterish tale. This animal is entirely nocturnal; it seems to be an unhurried creature, ready to melt into the darkness at any moment. It is a highly adapted forest rabbit.

Pink-eyed in my search-beam, these dark animals appeared thickset, heavy and short-legged, with short, rounded ears and virtually no tail. This is the sort of animal that is difficult to study. After all, it lives in dense hill forest that is also home to one of Japan's renowned poisonous snakes. Wandering around at night in a snake habitat is not for the faint-hearted. I wondered how the rabbits avoided them -- perhaps their thick fur and short extremities reduce the chances of them being bitten, and if bitten reduce the likelihood of venom penetrating.

The Amami rabbit is a stocky creature, measuring 40-50 cm in length and weighing up to 2 kg. It was discovered by W. H. Furness and H. M. Miller in 1896, and named in 1900 the Amami black rabbit (Pentelagus furnessi). Its distinctive morphology sets it apart from other members of its family, and recent genetic research indicates that its ancestors diverged from the main branch of the rabbit and hare family 10 or 20 million years ago.

These strong-legged rabbits are armed with unusually long claws, well suiting them for digging their solo burrows in the tough terrain of the Amami hills. The burrows provide daytime resting sites; the animals leave them at night to forage, browsing at ground-level vegetation on the forest floor.

Surrounded by coral reefs and situated in the central Ryukyus 400 km southwest of Kyushu, subtropical Amami Island is, like Okinawa to the south, a major center of biological endemism. Its lush subtropical forest contains tree ferns, cycads and an extraordinary collection of endemic species, including many of the Ryukyu Island regional endemics. Here the determined naturalist may find the dazzling cobalt and chestnut Lidth's jay, the enormous Otton frog and the Amami tip-nosed frog, in addition to the woodcock already mentioned and other local specialities, such as the Ryukyu robin and Ryukyu minivet.

The mysterious, nocturnal rabbit of Amami and adjacent Tokuno Island was discovered almost exactly a century ago, but its secretive habits have meant that its private life has remained enigmatic. Recently, however, Amami resident Futoshi Hamada has, by dint of prolonged patient observation and photography, revealed a few of the Amami rabbit's secrets.

Where the determined visitor might catch brief glimpses of a rabbit beneath the shelter of over-hanging vegetation beside a forest road or track, the most likely view is of the back end of one as it lollops off into the darkness. Following them into the forest is not an easy option. Even if one can dismiss the poisonous snakes from one's mind, the terrain is steep, rough and tangled with vegetation.

Nevertheless, Hamada has made it his lifework to tease out the character of the Amami rabbit. His patience has been rewarded with unique observations, astounding pictures of their private lives and some fascinating conclusions.

Amami rabbits usually live alone in simple, short burrows, using them repeatedly. A mystery of this creature had been their sealed dens; their purpose was a mystery. Hamada's observations have at last confirmed their function.

In such dens, female rabbits give birth and rear their young. But why do they seal their newborn youngsters away? Could this be their strategy for avoiding predation by snakes? Only when a mother's single youngster is old enough to follow her does she cease to seal up its den during the day.

Most extraordinary of all though is the fact that a mother doesn't visit her youngster every day. It takes about a month for her to rear her young, yet she only visits it once every night or two. Her milk must be astonishingly rich. Perhaps it is thick and energy-rich, like that of seals and whales.

Does this behavior help the rabbits avoid the attentions of the island's predatory pit-vipers, and if so, does it help them in any way against the recently introduced mongooses? Alien predators typically cause havoc among the vulnerable fauna of a remote island. It would be sad to think that the Amami rabbit had survived millions of years, coping with the attentions of predatory snakes and the vagaries of rising and falling sea levels, only to be wiped out by the hand of man, in the form of an unfamiliar, non-native mongoose that should never have been there. In such slap-dash, careless ways we "manage" our environment, pushing species toward extinction before we even begin to understand them.

The secretive forest rabbits of Amami are ancient members of a forest community that has survived in isolation for millions of years. Their ancient lineage and the richly diverse forests that they inhabit are not merely a unique Japanese legacy; they are a globally important focus of biodiversity.



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