Before there was IMAX, before there was the Discovery Channel and even before there were color movies, there were dioramas. These lifelike, still-life scenes, when rendered accurately, can still overwhelm the viewer—and teach about habitat, anatomy and behavior.

The 43 dioramas in the Bernard Family Hall of North American Mammals at the American Museum of Natural History (AMNH) in New York City are considered to be among the best in the world. They feature grand American bison grazing with pronghorn antelope on the Great Plains, majestic moose fighting at close range and wolves that seem ready to pounce out of their moonlit enclosure.

Dioramas might seem old-fashioned, but they allow visitors "to walk right up to the glass to check out individual features in a way you would never be able to do in a TV documentary," says Ross MacPhee, a mammalogy curator at the museum. "You can walk around them, see them from different angles—and that gives these presentations of natural history continued life."

Because of their careful construction in the 1930s and '40s with real plants and animals and ture-to-life settings, these scenes have remained captivating and convincing. But the decades of continuous display had led to faded fur, dusty leaves and yellowed snow. These slow shifts had made the exhibit both less engaging and accurate—a major failing in the eyes of animal experts like MacPhee. Many of the animals, such as the American bison, "went from all of these rich, beautiful browns and blacks to blond—nothing against blond; they just didn't look real," MacPhee notes.

In 2011 the AMNH began the massive task of assessing and restoring the historic dioramas—without permanently altering them in a way that would hinder future restorations. The project involved staff from many of the museum's departments, including curators, conservationists, exhibition preparators. But they also outsourced the some of the expertise. "We really needed a taxidermist to accomplish the recoloring," says Lisa Elkin, who directs conservation at the museum. But common taxidermy techniques had to be reinvented, and novel, reversible dyes created. Additionally, they had to devise new lighting sources and repurpose new materials so fragile scenes, such as snow-covered mountainsides, could retain their luster for decades to come.

Restoring the original coloring of these animals and their surroundings does not just provide a vivider visitor experience, it also preserves a moment in evolutionary time from the early 20th century. This enables researchers to track changes in coloring and habitat due to, for example, rapidly advancing climate change.

In October the Hall of North American Mammals reopened to the public after the yearlong renovation. Scientific American got a sneak preview of the exhibit beforehand. Here is how science helped the museum make this work possible.

View the slide show of the restored exhibits.

The real deal
In the 1930s the AMNH began work on perhaps the most ambitious real-life wildlife dioramas to date—and what would be some of the best ever accomplished.

The museum sent artists, curators and collectors out into the field across the continent—from the Grand Canyon to Mount Rainier to the Grand Tetons. For each scene teams chose an actual, existing place to re-create with plants, animals and scenery at the museum. Artists painted sketches, capturing the exact hills, streams, trees and rocks in specific spots. Collectors gathered plant samples to use and to re-create the snapshot back in New York; others killed the now-iconic animals that would be the centerpieces of these scenes.

Back at the museum, sculptors re-created each animal's body—down to musculature and tendons—in clay around a posed skeleton. "The anatomy on these specimens is absolutely incredible," notes George Dante, founder of the company Wildlife Preservations who led the taxidermy restoration efforts for the project. The original taxidermists tanned skins on models shaped to the sculpted bodies, then returned the preserved skins to each animal, ensuring a precise fit.

In the pre-plastic era of the 1930s museum artists used wax, paper, lacquer, wood, plaster, burlap and fabric to create convincing leaves, stems, rocks and other elements. With every detail composed to re-create the specific site, "you are transported to this spot," Dante notes. "Each one is a specific time and place. They serve an important purpose in that respect. So you can actually find this exact location and see how it's changed over time—how the vegetation has changed, how the landscape has changed."

Some of the best-known background painters, including James Perry Wilson and George and Belmore Browne, carefully captured the scene using an exacting grid system to make these curved-wall backgrounds appear infinite.

The trouble with time
The first 10, masterful dioramas—including the American bison and pronghorn antelope, the Alaska brown bear, the moose and the wapiti—were sealed behind glass for the 1942 opening of the exhibit. An additional 19 were added in 1954 and small mammal dioramas were completed in 1963. And rarely had any of the dioramas been touched since; one was opened to replace a fallen branch and another to restore faded snow.

They had not even been opened to rectify small inaccuracies. Most dioramas were meant to represent the snapshot in time when the animals were collected. But in the American bison and pronghorn antelope diorama, the scene was intended to depict the herd structures present in the mid-19th century, when bison still roamed free in great numbers. One visiting botanist, however, had noticed that the grasses in the foreground were invasive, nonnative species that had arrived by the 1930s but would not have been growing on the Great Plains in the 1850s.

In addition to new scientific understanding, the material integrity of the animals themselves began to shift, adversely affecting their accuracy. Over the years, the dioramas acquired a well-worn dusty look, as they faded far from their original coloration. The unfiltered fixtures that illuminated these displays had rarely been upgraded in the past 70 years, which meant the dioramas were being bombarded with UV-wavelengths that sapped the colors out of the animals' natural coats and some of the scene elements, such as snow—and as Elkin points out, "nobody likes yellow snow."

The new for the old
With the restoration project, museum experts at last had an opportunity to return the scenes to good scientific standing. Their main priority was restoring faded animal furs to their original colors. One of the major challenges was "gaining access to the taxidermy without damaging the dioramas," Elkin says. "While we were trying to remedy one thing, we didn't want to damage another." Some of the smaller animals could be carefully removed but many, such as the 500-pound bison, were too large to risk transporting. For these animals the museum built temporary wooden scaffolding into the dioramas to save fragile grasses and plants from being trampled, allowing conservators and taxidermists more freedom to work inside. (This intimacy was not always easygoing, however; "the wolves were a little scary when the glass comes down," says Elizabeth Nunan, who worked with Elkin on the conservation aspects.)

Taxidermists often use paints, hair dye and other traditional pigments for coloring. But for these historic displays, the museum needed a substance that could easily be removed in the future (should better technologies come along). They also needed coloring that would not alter the fur, could be cleaned easily and stand the test of time.

"We didn't want to use paint because the binder in the paint would bind the hairs together," Nunan says. And hair dye would have been difficult because it often requires heat and time to set it and would be difficult to do in delicate patterns, such as those on the jaguar; it also would not easily rinse out. "We were surprised about the limited amount of research that had been done on this," she notes.

The conservation team tested various alternative compounds on sample fur patches, examining them at the museum and shipping them off to be tested in accelerated-aging labs at Carnegie Mellon University and Buffalo State College. There, the samples were exposed to extreme light, heat and humidity to test their ability to stand up to these elements over 10, 20 or 50 years.

Conservationists also needed to match the original 1930s colors of the animals' fur, which was not easy to do—especially because the photographs from the original exhibition preparation are black and white. So Dante and his colleagues were able to borrow historic furs in the museum's collections that had been kept in dark storage to use as the baseline for colors and shading. Each animal also requires several shades, Dante notes. (The American bison, for example, each had eight different colors applied to them.)

But the work paid off. "What we came up with was truly groundbreaking—it will change the way these materials are treated," Elkin says.

The conservation team settled on an ethanol-based dye with metal components to improve color stability, which is similar to those that have been used in textile conservation. And it was light enough that it could be applied with an airbrush sprayer. "It's never as good as the real thing, but it's pretty close," Elkin says. "We've accepted that there will be fading of the dye, but it won't happen in any detectable manner for another 50 years," which, as she points out, will probably be time for another restoration anyway.

In addition to much of the fur, some of the ears, noses and other hard elements needed updating. "Almost all of the prosthetics developed for noses when the taxidermy was created used waxes or wax blends," Elkin says. "Those materials age poorly over time, so the fine detail had been lost." So the American bison and the collared peccary both received nose jobs to restore some of the original texture and fill in cracks. The antelope jackrabbit also had its ears updated to emphasize their signature veins.

Old, faded snow scenes, such as that featuring the Canada lynx and snowshoe hare, had once been created out of medical grade cotton topped with glitter. But by shifting to more modern materials, including silicate fiber that is used to line kilns, chopped up Ethafoam and UV-stable glitter flakes, the conservators hope this new arrangement will retain its white luster for decades to come. Now, notes MacPhee, the diorama looks "absolutely realistic, so you're perched right here on the mountainside next to the lynx."

Other minor touch-ups throughout the exhibit hall were also needed, including a faded rhododendron in the skunk diorama. The conservators carefully studied archive photographs to see where small changes had occurred over time, such as cactus spines shifting or bending.

Finally, to stave off future deterioration of the dioramas and to reduce energy use, the museum reimagined the lighting strategy for the hall. "A large part of the project was focused on re-lamping," Elkin says. For delicate textiles and other artwork, gallery lighting is often carefully controlled and kept at a dim level. The dioramas, however, have different demands. "In the bison diorama, they needed to mimic high noon on the plains—it's a blasting light," Elkin says. Each diorama now has energy-efficient light bulbs and filters "so that UV problem will not come back to haunt us," MacPhee notes.

The improved lighting, however, also created problems for the original illusions in some of the displays. In the moonlit December snow scene that showcases the wolves running along a Minnesota lakeshore, for example, the energy-efficient lights cast new shadows that disrupted those painted to be cast by the moon. So museum artists had to add new coloring to the snow to mask these new shadows.

"Now they're as beautiful as they day they were installed," MacPhee says. "All of these specimens now look like Angelina Jolie and Brad Pitt for their particular species. They are beautiful to contemplate. And that's what we want—we want people to have that kind of reaction to wildlife."

View the slide show of the restored exhibits.