PITTSBURGH >> As a National Aviary volunteer, Janet Robb accompanied a visitor into the Tropical Rainforest habitat, and both women gasped out loud at a rare — almost magical — sighting. Wookie the sloth was in plain view, hanging upside down on a low-hanging tree branch. His big eyes peered directly into the visitor’s eyes.

“It’s a National Geographic moment!” exclaimed Robb, who is the 2021 Volunteer of the Year at the bird zoo, on Pittsburgh’s North Side.

The sloth, seldom seen by visitors, prompts the continuous query, “Where’s Wookie?” (He is usually high up in the tops of trees where his brown fur blends in with bark and branches.)

Although Robb has volunteered more than 10,000 hours at the aviary since November 2009, none of this ever gets old. Her genuine enjoyment of the 150 species of birds — and the handful of mammals who cohabitate with them — is evident. She especially enjoys sharing her knowledge with visitors.

The mission of the 70-year-old aviary includes breeding and caring for endangered species and raising awareness of birds in the wild and in zoos.

“Our volunteers play a vital role in helping the National Aviary fulfill its mission,” said Angelica Miller, volunteer coordinator.

Robb certainly does that — plus more.

She was volunteer of the year in 2010 and 2014, selected because of her “strong leadership, excellence in visitor engagement and ongoing commitment,” according the aviary.

For 39 years Robb taught public speaking at McKee­sport Area High School. After retiring she was looking for meaningful, interesting volunteer opportunities.

“I saw an ad in a magazine for retired teachers. It said the National Aviary was looking for volunteers. I knew nothing about birds and had never had a bird for a pet, but I applied,” she said. “I thought I would be handing out brochures or helping people find their way around.”

She was pleasantly surprised when the staff provided training that enabled her to teach classes and conduct encounters with the sloths, penguins and other animals.

She holds “bat chats” about the flying foxes that are mammals native to Malaysia and Southeast Asia. Nutmeg and Bouy, both 16, and Maroon, 18, have 6-foot wingspans and cute furry faces that resemble Chihuahuas.

One of her tasks is preparing meals for aviary inhabitants, including the big bats.

“They especially love watermelons,” she said.

She handles birds in the aviary’s flight shows and even helps with the lights in the indoor theater.

Visitors pay $95 for up-close encounters with the sloths, and the slots quickly sell out. People cry with happiness when they meet its stars, Vivian and Valentino, Robb said.

As for Wookie, volunteers and staff always know where he is hanging out, and they’re happy to point him out to visitors and provide fun facts. “Wookie is 21 years old, and he’s been here for 18 years,” Robb said. “He weighs 25 pounds, which is about as large as a sloth gets.”

She knows the names of all the animals, pointing out hyacinth macaws Benito and Sapphira. Amid a loud “woo woo!” Robb chuckled and said, “That’s Gus, the great argus. You can hear him throughout the aviary.”

Sometimes there are new experiences and discoveries.

“There’s Bubba, a palm cockatoo. One morning before the aviary opened, I heard him talking to himself, saying his own name over and over,” Robb said.

The gray bird declined to repeat that trick, of course, sitting calm and mute before his visitors.

In the big, open habitats where the birds fly freely, many are accustomed to being in close proximity to people. Some come very close to visitors.

“I think they think we’re just big, funny birds,” Robb said.