This story first aired on 6/9/2016. 

Stuffed animals peer from shelves in the new Avenir Collections Center at the Denver Museum of Nature and Science 

(Sam Brasch/CPR News)

What's the best place for that dead squirrel in your backyard? 

You might think the trash can, or maybe just over your neighbor's fence.

But as it turns out, the Denver Museum of Nature and Science might want to keep it in its new massive collections facility. 

The museum has amassed around one million zoology specimens over its 116-year history. Most of those critters are bugs, but the museum also boasts around 70,000 birds and mammals. Almost all have now been centralized into the new Avenir Collections Center. The museum's earth science and anthropology collection will also be brought into the new facility over the next few months.

"It's a big deal," said John Demboski, the museum's zoology curator. "It's taken years to move. A lot of the objects are very delicate."

Denver voters passed a bond in 2007 to help pay for a $70 million museum expansion that included the new facility. The space has drawn national attention for its climate control and state-of-the-art labs. 

You have to descend from the museum's main public floor to get there. Stuffed jaguars and cranes peer down from shelves. It's as if the Apple Store had a taxidermy section. 

But even with the futuristic look, the point of the collection is to preserve the ecological past for researchers. That mission is likely to become even more important as forces like climate change and land development threaten biodiversity in Rocky Mountain ecosystems. Many of the species found in the basement are extinct from Colorado while others are gone from the planet altogether.

There are bison from the 1870s -- some of the last to run wild across Colorado. There are passenger pigeons -- a bird once so numerous in North America that flocks blocked out the sun. Now they're extinct. There are two beach-ball sized eggs -- the product of 9-foot elephant birds that once tromped around Madagascar. There's even the last wild grizzly bear to be killed in Colorado. 

The last wild grizzly bear to be shot in Colorado, now stored in the new Avenir Collections Center at the Denver Museum of Nature and Science. 

(Sam Brasch/CPR News)

Demboski opened a drawer to reveal its pelt. 

"Colorado was one of the last holdouts for grizzly bears in the West," he said. "We had them until around the 1950s, then this bear popped around in 1979." More precisely, the bear attacked guide Ed Wiseman in the San Juan Mountains. He killed it by hand with an arrow.

"As a biologist, you see a lot of what's going on with human impact on biodiversity. So a lot of my job as a curator might be to document biodiversity, but it might also be to document biodiversity declining," he said. "That's kind of the sad side of the job here."

Room To Grow

Even so, that hasn't stopped Demboski from rapidly growing the collection. In his 10 years at the museum, he's put a new emphasis on "salvage" animals that end up dead in Colorado. That includes everything from dead backyard squirrels to expired elephants from the zoo. 

He said it's a change in philosophy for the museum, which in decades past would commission hunters to bring the wilds of Brazil or Africa to Denver for display. 

Now the focus is research on the local environment. Demboski's main suppliers are people like Lea Peshock at the Greenwood Wildlife Rehabilitation Center in Longmont. She keeps animals that come in dead or need to be euthanized, then delivers them to the museum. The Denver Zoo does the same with ostriches, rhinoceroses and other exotic animals.

The museum took in 4,ooo birds and mammals from salvage last year. Demboski said that they've only collected around 800 this year but things tend to pick up in the summer and fall. 

The recent move has made it a challenge to keep up with the numbers of animals arriving. So at the moment, thousands of animals wait their turn in a walk-in freezer. Most the critters are concealed in plastic tubs but a plume of green feather sticks out of one trash bag. 

"Yeah, that's a whole peacock from the zoo," said Demboski.

How To Catalogue Roadkill

The freezer is so daunting to sort through that Demoboski let one relatively lucky fox squirrel skip the line and go straight to the museum's prep lab. 

The critter lay on a metal table. A car had crushed part of its backside. Demboski said the condition of the specimen doesn't matter much when he decides whether or not to add it to the collection.

A dead fox squirrel waits to be added to the zoology collection in the Denver Museum of Nature and Science's prep lab. 

(Sam Brasch/CPR News)

"Usually the criteria is whether it has data or not," he said. "We are looking for a lot of information on these specimens and that's what makes them valuable from a research perspective."

The squirrel met the bar. Its record showed the exact coordinates of where it'd been found and when. The record also tracked its journey to the museum: first from beneath the wheel of a car, then to Longmont Animal Control, then to Greenwood Wildlife Rehabilitation Center. The animal was euthanized upon arrival. 

In the prep lab, James Gilman set to work. The retired pediatrician is one of the museum's 150 zoology volunteers. At 82, he's also one of the longest-serving.

He laid the squirrel on a work table and lowered a vacuum above the carcass to keep the smell down. He carefully removed the skin from the skeleton.

James Gilman, 82, prepares a fox squirrel to be added to the permanent collection at the Denver Museum of Nature and Science. The museum has over 150 zoology volunteers. 

(Sam Brasch/CPR News)

"When I finish this, I will open up the bowel and look for parasites," he said. "It's kind of like doing a super-manicure."

In the meantime, Demboski showed off how the museum cleans skeletons for preservation. 

"The way we do it -- and the way a lot of museums do it -- is we actually use flesh-eating beetles."

He lifts the lid on a plastic tank that once held 3,000 gallons of agave nectar at Whole Foods. Thousands of beetles and larva crawl over the skeletal remains of a camel and other former fauna.

The Denver Museum of Nature and Science uses dermestid beetles to eat flesh off of animal bones in a tank that once stored agave nectar at Whole Foods. The bones will be added to the museum's collection once they've been polished clean. 

(Sam Brasch/CPR News)

Demboski said that the bugs will polish the bones clean in a few weeks. Then they'll be labeled, boxed and linked to online databases.

Built for Big Data

In his office, Demboski showed how his collection exists in the digital world -- and how it offers new possibilities for researchers. 

He pulled all the records of fox squirrels from around the Front Range. Dozens of records popped up, each one linked to an exact location in place and time. He clicked one. The map zoomed to a single backyard in Denver. 

Then he zoomed out past Colorado to see all the records of fox squirrels found in the U.S., then all the wild mammal specimens cataloged around the planet. The museum links its massive collection to others through public databases like BioPortal. He said that gives scientists a whole new way to understand the natural world.

The Denver Museum of Nature and Science dries animals that have been salvaged from the local environment. These so-call study skins will soon be added to the new Avenir Collections Center. 

(Sam Brasch/CPR News)

"You can start seeing how species are moving around and changing. And then the question is why. Is it a climate change issue? Is it an invasive species?"

Those questions drive him and why he says the extra space in the new facility matters. It'll let him keep taking in dead critters to help researchers understand the changes on their way to Rocky Mountain ecosystems.