Habitat for Anna's Hummingbird is based on an ornithological diagram for California's hummingbird population that represents the bird's annual cycle of breeding, migration, and molt through a series of staggered arcs. Chadwick Studio, a product design firm based in Los Angeles, has reinterpreted that design as a three-dimensional circular planter supporting both native and non-native flowering plants. (Brian van der Brug, Los Angeles Times / May 30, 2010)

A pair of professional arborists, licensed to climb and care for trees, were perched high in the branches of a 110-foot Monterey cypress in the Presidio park of San Francisco. Secured by harnesses and a web of rock-climbing ropes used for rappelling down the trunk, they were awaiting instructions from the ground.

"Could you try the limb below your right foot?" said their boss, landscape designer Peter Good.

"Is there any way to get the nest to stand more vertically?" asked gallerist Cheryl Haines.

It took a team of four people a full day to do what birds do so naturally: find a good and safe place to build their nests.

Only in this case the goal was visibility from the ground for the sake of park visitors, as well as safety for any nest residents.

For the bird "nests" being placed in the tree were actually manmade art objects: nine exquisitely patterned blue-and-white porcelain vessels designed by Chinese artist Ai Weiwei as part of a larger public art project developed by Haines through her nonprofit foundation For-Site.

For the project, Haines invited a number of artists, architects and designers to create habitats for the animals of the Presidio, a 1,491-acre national park that used to be a military base. Of 25 proposals, she chose 11 to produce.

"The participants designed homes for animals, much as an architect designs a house for a client," says Haines, now watching the third of Ai Weiwei's porcelain nests—envisioned as a shelter for the Western screech owl—positioned in the tree.

The total project cost around $900,000, she said, with For-Site raising all funds through private donors. "It's meant to be a gift to the park and everyone who uses it," she says. Yes, she says, animals included.

The realized works are wildly different in look and feel, ranging from a pyramid-shaped fox den made by the Danish architects CEBRA out of surplus Presidio cypress to a flowering amphitheater-shaped feeder for Anna's Hummingbirds courtesy of L.A. designer Don Chadwick.

L.A. architects Taalman Koch created another—more modern, even futuristic--home for the tiny screech owl in the form of a multifaceted dome made out of aluminum, while L.A. artist/designer Fritz Haeg made a wooden tower for a handful of species, from snakes to bats, to inhabit.

Another highlight, quite literally, is a set of 10 bright yellow steel chairs that Jensen Architects of San Francisco planted in and around a meadow to pay homage to the blue heron. The chairs can be used for bird-watching or bird-perching, and droppings are already visible.

These projects, installed at various spots towards the northern base of the Presidio this month, will be up until May 2011. You can pick up a map at the exhibition pavilion for a self-guided tour that runs about three miles. The pavilion, designed by Ogrydziak/Prillinger out of recycled shipping containers, also has a great view of the Golden Gate Bridge.

The Presidio Trust, a government agency that oversees the park, bills it "the first site-specific art exhibition" to take place in a national park. "It's the first we've identified," adds Michael Boland, planning director for the Trust. (He clearly does not count Andy Goldsworthy's soaring wooden spire, the first project that For-Site realized in the Presidio, as an "exhibition.")

"There's a long history of artists like Ansel Adams or Albert Bierstadt who interpreted national parks through their photographs or paintings," Boland says, "But there isn't so much when you look at artists interpreting national parks using sculptural interventions or site-specific projects."

Boland said the new project is meant to highlight the park's "incredible biodiversity," noting that some 300 species of native plants, 200 species of birds and 60 species of bees make their home in the park—"not just in the wild areas but in the more developed regions as well."

Whether the animals will make themselves at home in the artworks is an open question. Some of the projects, like Ai Weiwei's nests, "are intended perhaps to coax an animal who no longer lives here back into residency," says Haines. "Others are for actual animals that live here, what Fritz Haeg calls 'the animal client.'"

Haeg, the category-defying artist, architect, gardener, urbanist and educator, explains what he means by the term. "I have an architecture background, and I put on my architect hat when I design things for animals," he says.

"They don't happen to have money and they don't happen to have language—so our communication is mediated by wildlife experts. But animals are equal partners in our cities."