Ginger Sturgeon was walking along the pathways of Pittsburgh Zoo and PPG Aquarium recently when she heard a chorus of what sounded like honking, out-of-tune violins. With around half of the zoo's employees working remotely and the public barred from entry, Sturgeon was the lone audience member for this discordant symphony. 

"The flamingos just started calling and actually ran over to the fence to greet me. They're a very gregarious species," said Sturgeon, director of animal health for the Pennsylvania facility. "They were just really excited to see somebody."

Across the country, zoos and aquariums have closed to the public amid widespread efforts to stop the spread of the novel coronavirus. The shutdowns have allowed for delightful videos of penguins marching around empty parks, but they haven't stopped work at the facilities. Zoos house hundreds of thousands of captive animals that rely on people for their food and care - and that means people like Sturgeon are still reporting for duty each day.

But that work now looks vastly different. Nonessential staff is at home, and the skeleton staff that remains must work while also practicing social distancing. Some facilities are hitting the pause button on non-emergency procedures, such as trimming donkeys' hoofs. Keepers are more often wearing masks. Nutritionists are working to secure rare foods for animals with limited diets.

"It's surreal that we're in this situation," said Doug Warmolts, vice president of animal care at the Columbus Zoo and Aquarium. "It's something you think about and you plan for, but you never think it's actually going to happen."

Typically, zoo staffers perform lots of preventive care for their animals, such as routine vaccinations and physical exams. But to protect keepers, many of these procedures require at least two people to handle, maneuver, restrain or relocate an animal - and that isn't doable at a 6-foot distance from co-workers. Large animals such as elephants, and dangerous animals such as venomous snakes, simply can't be handled in some cases.

There is also some concern among zookeepers that the coronavirus, which is believed to have originated in bats, could migrate from humans into other species. Primates, for instance, are already known to be susceptible to human viruses, and scientists warned this past week that the coronavirus could pose a mortal threat to endangered great apes.

"We always wear face masks when we're doing an exam of a great ape," said Nadine Lamberski, chief veterinary officer at the San Diego Zoo and the San Diego Zoo Safari Park, which is home to gorillas, orangutans and bonobos. "But in this situation, we're asking our wildlife care specialists to wear masks any time they're even in an area with the primates."

The Pittsburgh Zoo is being extra vigilant with its giant anteater, a species vulnerable to human influenza. "I have no idea if the coronavirus could go from a human to anteater," said Sturgeon, "but we're using an abundance of caution."

There are also supply chain concerns. Some animals rely on a small variety of foods that could become unavailable if shutdowns persist or sickness sidelines large numbers of people who work for suppliers. In San Diego, platypuses are the picky eaters.

"They have a preferential diet of eating yabbies, or crayfish," said Lamberski. "And the fact that they prefer them to be alive is the challenge."

In the event the local supplier of the platypuses' favorite meal is unable to provide it, zookeepers are exposing the animals to other options a bit at a time. Mealworms, crickets, night crawlers and a crustacean called ghost shrimp are now on the menu.

"We are actually doing some feeding trials with them now to see if they will accept frozen, thawed crayfish," said Lamberski. "But it's too soon to comment on those results."

At the Florida Aquarium, CEO Roger Germann said staff members are stocking up on a resource that many people don't think about when it comes to shortages - faux seawater.

While the aquarium sits right on the waters of Tampa Bay, it's in a fairly industrial area, and the water quality isn't pristine. So about 20 years ago, the facility started sourcing its seawater from barges that come in from the Gulf of Mexico. "It's just a nice, fresh pot of water, and it helps our animals," said Germann.

There's an alternative in a product called "Instant Ocean," which is basically dry sea salt in a box. But when added to water, Instant Ocean creates an artificial saltwater with levels of magnesium, calcium and other minerals designed to sustain creatures including octopuses and coral, garden eels and stingrays.

Most important, Instant Ocean "can sit on a shelf for a very long time," Germann said, so the Florida Aquarium has begun to stockpile it in case its pipeline to the open ocean water shuts down.

If supply line interruptions get dire, some animals might have to be relocated to facilities closer to resources they need, Warmolts said. For instance, the Columbus Zoo has greenhouses dedicated to growing emergency supplies of eucalyptus for the koalas. But those might last only a few weeks if the zoo's regular shipments of the greenery, from Arizona and Florida, halted. In that case, the animals might be moved to zoos in the south, where the koala food grows more easily, Warmolts said.

Zoos say handlers are now giving animals extra enrichment opportunities and exercises to make up for the lack of interaction with visitors. At the same time, several of the zoos and aquariums say they are also working to keep morale high among their humans.

The Florida Aquarium is continuing to pay all of its staff, even part-timers, despite being closed, Germann said. About 40 people are still required to report in person, while the other 60 are working from home. The aquarium is also bringing in catered lunches each day, both to thank employees and to cut down on their exposures, and also as a boost to local small businesses.

In Columbus, on-site employees are snacking on 125 boxes of Samoas, Tagalongs, and Do-Si-Dos supplied by Heather Carpenter, a gorilla keeper and leader of Girl Scout Troop No. 249. Its annual cookie drive was canceled on account of the pandemic.

"Keeping spirits up as this drags on is going to be a huge challenge," said Warmolts.

In the meantime, some zoos and aquariums are also working to cheer up the millions of people stuck at home. Many are streaming live-feeds of their exhibits, posting videos and blog posts, and taking to social media to keep the public connected to their animals.

On Monday, the Pittsburgh Zoo's spacious parking lot was converted into a drive-through COVID-19 screening area.

Amid it all, life goes on. A gorilla named Uzumma gave birth at Seattle's Woodland Park Zoo earlier this month. And in Columbus, a polar bear cub just learned about this thing called "water."

Since its birth in November, the cub and its mother have been in isolation to simulate natural denning activity. Now the cub is slowly being given access to new parts of its enclosure - most recently the pool, a foray that can be viewed online.

"It's hilarious and fun to watch," said Warmolts. "There's still joy in watching him experience the world for the first time."