IF you've never been to the Sonora Desert, you can't imagine what a strange place it is. The mountains are covered with scrubby vegetation. They look mysterious, almost like headless camels. And the local plants are straight out of moviedom's special-effects department. The wildlife is more familiar. Tarantulas, snakes, lizards, and coyotes do well here, of course, and in the higher elevations, bears, mountain lions, and mountain goats. In the more southern reaches of the desert, in Baja California, you get some pretty fancy birds - thick-billed parrots, for instance.
As for plants, it takes a genuine oddball to survive here. Like the saguaro cactus -- the plant that lets you know you're in the Sonora. Or the cholla cactus, whose flabby, grayish fruit can latch on to the unwary passerby with nasty prickers.
Over 300 different kinds of animals and 200 kinds of plants inhabit 15 landscaped acres, set in the heart of Tucson Mountain Park. Most zoos and botanical museums have to range far and wide to get specimens, but the Arizona-Sonora Desert Museum is strictly regional and proud of it. The curators don't even water their plants.
The great thing about the museum is that the local surroundings have been compressed and intensified for you. A few of the plants you'll easily see elsewhere in Arizona, but as for the wildlife - you'd have to be a naturalist to find it.
And now the museum is doing its best to make you forget that it is a zoo at all. A new $2.5 million habitat has just opened, designed so that you can see white-tailed deer, mountain lions, brown bears, and other mountain animals, all in enclosures of convincing-looking fake rock, with the natural mountain backdrop behind them.
This is part of a grand reorganization plan to take place as funds are available over the next few decades. The old format showed caged animals sorted by classification: snakes with snakes, cats with cats, and so on. The modern approach is putting predators and prey and the plants that go with them, close together in a natural setting.
Elevation is the critical factor here, not because of the difference in heat but the difference in water, according to Christopher Helms, development and public affairs officer. The new habitat represents the desert's highest elevation, and it features, among other plants, 200-year-old Arizona white oak trees and some magnificent ``evergreen oaks,'' as they are called here, all transplanted from a rancher's land.
Building a new museum like this is strictly a custom job. ``These exhibits are different from those that exist anywhere else,'' said Mr. Helms. For one thing, there is no guarantee that the animals' needs and the designer's ideas will coincide. The talk of the museum the week I was there was the pranks of two five-month-old bears. First, one bear caused a furor by almost staging a getaway. Then both bears gave a keeper the shock of her life when she happened upon them in the neighboring den for the gray foxes, who hadn't moved in yet; their area was designed to be mercifully bear-proof. (Both escape hatches have since been redesigned.)
Peter Siminski, curator of birds and mammals, took me for a behind-the-scenes tour. There's something enchanting about seeing a zoo with an insider; the animals all come trooping over to you. An exception was one of the jaguarundis, a recent mother; she bared her fangs at me -- a savage red and white snarl in a small chocolate-colored face.
We visited the animals' kitchen, which included a walk-in freezer full of, among other things, great bags of Purina Dog Chow. It was the animals' monthly ``goodie day,'' so plates of special raw meats were everywhere.
He led me over to the cage of the vampire bats - small furry balls hanging upside down. They have nasty expressions and are fed bowls of blood at mealtime, according to Mr. Siminski.
We also passed a cage containing three elf owls, sitting on their perch. Spying us, they abruptly drew themselves up to their full four inches, swiveled their heads toward us, opened their eyes wide, and froze. They looked like something ceramic you'd buy in a gift shop.
``When will they straighten out?'' I asked, as the owls locked into position.
``Oh, they will, eventually,'' said Siminski casually as we walked off, leaving them to it.
At the time of my visit the animals in the new habitat were just getting used to their quarters. ``We have to get animals used to their enclosures so that they know where they live,'' said Siminski. This procedure is complicated when there is more than one species in an enclosure, because each species has to first get used to its cage, then to the outer, public area; then both species must be put together so they can get used to each other.
We went behind the scenes to the cage area to see the mountain lion, who was at that point in the ``cage stage'' of the adjustment process. The bears came back into their cage area to have a look at us.
Bears like to play to the gallery. One stuck his nose through the bar in an aren't-I-adorable sort of way, then rolled back on a small fat rump, giving a great impersonation of a bear who would never in his wildest dreams think of biting anybody. ``Bears can sucker you; watch out,'' Siminski said warning me as we went by.
The mountain lion had just lost his mate and was sitting alone in his new cage. His opinion of the situation was expressed in the low set of his ears, a resigned look in his steady golden eyes, and in a certain lack of animation about the tail. He seemed glad to be visited though and began making an irregular hoarse growling noise that Siminski said was the sound of a mountain lion purring. ``He likes you,'' he said.
A later phone call revealed that the lion is now out in his enclosure, has cheered up, and a new mate has been acquired for him. He has taken to living in his viewing window and interacting with visitors.
It is a wrench to tear yourself away from a purring mountain lion. But we went on to the museum's wonderful walk-through aviary. On our way, we wandered past a coyote, looking like a friendly husky dog grinning and squinting in the hot sun; fat prairie dogs, like overgrown hamsters, surrounded by a crowd of admirers; and a cardinal on top of an ocotillo. We also passed several docents, one with a beautiful owl on a leash, another holding a large turtle.
It was hot, and many of the birds you can usually see in the aviary were hiding, though we did see a magpie jay, with its sweeping tail of black and white diamonds. The birds seemed very happy here: ``Lots of birds try to get in,'' said Siminski. The aviary is an example of the interaction between the museum and its environment. ``If you notice all the birds looking up, look up and you'll see a hawk.''
I said goodbye to Siminski and wandered around the museum for a while by myself. There are many strange and beautiful sights here. There is a room full of minerals like great lumpy jewels: azurite, flat plates of the brightest blue; malachite, fuzzy jade green blobs; tangerine colored wulfenite; and calcite, like frozen milk. Then I went outside again.
Talking to people here, you get a different view of the less likable animals and insects. I saw one man tenderly holding a gigantic tarantula in two thick, cupped hands. From him I learned that tarantulas -- at least the North American varieties -- are very remarkable and much maligned. They can live to be 25-30 years old, are docile, don't mind being picked up, and are not particularly dangerous even if tormented into biting, and are quite fragile. ``If I dropped her, she'd probably die,'' he said, looking down at the motionless, doorknob sized beast, with its 5-inch long brown furry legs: the stuff of nightmares, squatting trustingly in his hands.
The Sonora Desert Museum was founded 33 years ago by a self-taught naturalist named Bill Carr, who thought of what was then the standard museum of natural history as a ``dead animal museum,'' according to Helms.
``Most zoos are postage stamp collections.'' he says. But this one permits ``a willing suspension of disbelief.''