There are countless ways for school-age children to learn about the flora and fauna that inhabit the nation’s parks.

Books, browsing the Internet. And those adventurous enough to put down their smartphones and unplug from computers could even hike through one.

On Sunday, though, National Park Service Ranger Tony Linforth had a different approach: picking apart owl vomit.

“It’s cool but gross,” said 10-year-old Kate Snook of Greenbelt, who wants to be a park ranger like her mom, Lee. “I like finding things.”

Ever wonder what an owl eats? Linforth explained that an owl’s pellets, as the vomit is called, are the regurgitated remains of what it eats: the bones, fur, teeth, nails. All the stuff it can’t digest, he said.

Xena Sehgal, 5, looks through an owl pellet — owl vomit is called pellets — at Rock Creek Park. You can tell what kind of small mammals are in the park by looking at what the owls eat. (Matt McClain/The Washington Post)

“If scientists want to find out what small mammals are in an area, one of the ways they can do it — instead of trapping mammals, which often leads to fatalities — is they can go out and find where the owls are dropping their pellets,” Linforth said. “If they look inside the pellets, they can find what small mammals are in an area.”

The demonstration was part of a day of festivities kicking off the 125th anniversary celebration of Rock Creek Park, sponsored by the National Park Service and the Rock Creek Conservancy. During the morning event at the park’s nature center, kids were transformed into junior rangers and learned about the species of owls that live in the park and why they’re important.

Linforth told a handful of young rangers how these birds of prey swallow their food whole. He admitted that it might sound gross — but even an animal as large as a skunk can land on an owl’s menu.

Owls sit in trees and digest their food, he said. The stuff that’s left behind gets spit out in a compact little pellet about the size of a cocktail wiener that resembles a hairball.

“It looked like fur,” said Caroline Lidy, a 7-year-old from Northwest Washington, who had no idea what owl vomit was.

Eleven-year-old Peter Milius, also of Northwest, said dissecting the pellets was harder than it looked. “It was interesting but kind of hard because it kept breaking apart,” he said. “It was cool that we got to see what owls ate because I didn’t know any of this before.”

Linforth said the lesson was that animals are “different from us, yet they’re still the same.”

River Pintea White, 3, of Silver Spring, Md., bottom left center, stands next to a display of a great horned owl at the Rock Creek Park Nature Center and Planetarium during on Sunday January 25, 2015 in Washington. (Matt McClain/The Washington Post)

“They’re eating, but they’re processing their food in a slightly different way,” he said.

A few of the youngsters started gagging when they heard what Sunday’s experiment would entail. Linforth noticed the hesitation as the pellets were laid out on the table. That look: Is this clean? Is this safe? He said the pellets had been sterilized — the park buys barn owl pellets from a company out West.

Slowly, the hesitant youngsters began touching the pellets — pulling away the fur with tweezers, fingers even.

“Once they get through that first touch, that first feel, they lose their nervousness,” he said. “They get excited, and they start peeling away the fur and they expose a skull or they can see a tooth. Sometimes you can see the nails, the claws from the rodents that they’ve been eating.

“Just the look in the eyes of the kids sometimes when they see those teeth and they say, ‘Wow, that’s a skull.’ . . . There’s that understanding of what they’ve found.”

Park Superintendent Tara Morrison said the kickoff was planned for Sunday because of the date — 1/25, a play on Rock Creek Park’s 125th anniversary. Rock Creek became a national park on Sept. 27, 1890.

And, by the way, there are three species of owls in the park: the Eastern Screech, Barred, Great Horned.

“Owls are just one of the many birds we have here in the park, and when we’re in an urban environment we don’t necessarily think about making those connections,” Morrison said. “As we saw here today, the kids loved it: being able to learn about owls and the three species we have here in the park. And then to taking time to learn about what they eat and how that comes out and dissecting it. Just looking at some of the kids, I see future biologists.”

And in an effort to reach the masses, park officials — in partnership with Rock Creek Conservancy — are even developing an app to help visitors navigate Rock Creek’s trails.

But for the young rangers, the day’s highlight was bringing home a little souvenir in a manila envelope. Five-year-old Xena Sehgal of Bloomingdale in Northwest said she couldn’t wait to take pieces of her pellet home.

“I’m going to put it in a bag,” said Xena, who wants to be a doctor after dissecting pellets for the second time Sunday.

Eight-year-old Simone Joyner of Petworth said she wants to show her sister and her mom what owls eat. The most surprising part? “All the bones you found in one pellet,” Simone said. “It was cool to take all the bones out of the pellets.”

Simone’s dad, Brian Joyner, said Rock Creek Park is the city’s hidden gem.

“There’s other aspects of the park other than driving through,” he said.

And owl pellets?

“I kind of got into it,” said Joyner, 47. “I thought it would be rude to take the pellet from the child and spend all the time with it.”