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Once it was regarded as a scientific hoax--now it's merely an "honorary mam- mal"

On a windless night with no moon, I wait patiently in a mossy recess of one of the wildest places I have ever known--the primal forest of New Zealand. The silence is deafening, the darkness total. My senses are so acutely sharpened I can hear my own heartbeat.

Suddenly, an electrifying shriek tears apart the stillness: Like a steel blade stabbing the night air, a territorial call rips from the forested ridge just beyond me. Half scream, half whistle, repeated over and over again, the stri- dent notes rise with intense conviction--questioning, asserting, proclaiming. "Cruuuik, cruuuik, cruuuik!"

I hold my breath, feeling the hairs stand up on the back of my neck. Within seconds, an answering volley erupts no more than 15 meters (50 ft.) away from me in the inky darkness. These calls are equally forceful but infinitely har- sher, a combination growl and scream sounding remotely like the creaking of a very old, very rusty, very loud barn door.

Just as abruptly, silence returns to this forest that has remained virtually unchanged for 70 million years, and I am left to marvel at my good luck. I am at last in the company of one of the world's most bizarre, most secretive and most well-loved birds, and I have just witnessed a female respond to her lifelong mate. My quarry is the New Zealand kiwi, arguably the most un-birdlike bird that ever existed.

So strange is the kiwi that it was once regarded as a scientific hoax. More recently, it has been termed an "honorary mammal." For a start, the kiwi is completely tailless and flightless, not even able to flap the stubs of remnant wings for balance. Long, catlike whiskers accompany shaggy, hairlike feathers. Sturdy, muscular legs--a third of the bird's body weight--enable it to lope through the forest. Like some rodents, it is nocturnal. Like a badger, it lives in burrows.

Most amazing of all are the bird's senses. The kiwi has traded the keenness of avian eyesight for acute non-avian senses like hearing and smell. Its ears are so well developed they can be seen easily through furlike head feathers. And its sensitive "nose" can sniff out food as acutely as can any dog.

The kiwi's extraordinary beak--which is incredibly long and thin and, in con- trast to all other birds, has nostrils near the very tip--is a combination scent detector, probe and forceps. A kiwi can thrust this 18-centimeter-long (7 in.) device completely underground to sniff out earthworms, its favorite food. Or it may lift it into the air to detect smells wafting on the wind. This unorthodox tool allows the kiwi to snuffle along the forest floor like a hedgehog and probe the ground for invertebrates like an anteater.

Equally unusual is the way kiwis breed. The female is up to 30 percent heavier than her mate and produces one of the largest eggs in relation to body size of any bird, up to 20 percent of her own weight. A chicken of the same size lays eggs less than one-sixth as large as the kiwi's. This giant kiwi egg consists of nearly two-thirds yolk, an incredible energy investment.

Not surprisingly a wild female kiwi lays only one or two eggs a clutch, which she may leave entirely to her mate for an incredible 70--to 80-day incubation. When a chick finally hatches, it is already fully feathered and resembles a miniature chip off the parental block. At the age of two weeks, it will wander off into the forest alone, a fully autonomous mini-kiwi.

All these thoughts flood my mind as tonight I try to imagine this pair on independent foot patrols of a shared territory, which in some cases may be as large as 40 hectares (100 acres). Where did kiwis come from and how did they come by such a mammalian lifestyle?

The story, I realize, goes back some 70 or 80 million years to the time of the break-up of the super-continent Gondwana, when what was to become New Zealand first split away from the rest of the world's land masses. At that time, mam- mals were still an evolutionary minority, and birds reigned. On an island which to this day has never known native land mammals except bats, it would be only natural that a bird like the kiwi would come to be.

Kiwis appear to be distantly related to the rest of the flightless ratite fam- ily, like ostriches in Africa and emus and cassowaries in Australia and New Guinea, although they are by far the smallest of the tribe. There are actually as many as six different forms of the bird, divided into four main types: the brown kiwi, the tokoeka, the great spotted kiwi and the little spotted kiwi. These range in size from a small bantam hen to a Rhode Island Red, two-and a half times bigger.

# posted by Medical Information : 3:19 AM