But Nadia’s test result six weeks ago was only the beginning of an unprecedented series of crises—some existential—faced by zoological parks dedicated to the study and survival of thousands of the Earth’s other animal species. Unlike entertainment centers, movie theatres, or sports stadiums, zoos can’t simply shut their doors or tell staff to work from home. Zoos still have to feed and care for animals—nearly a million, from six thousand species (a thousand of them endangered or threatened) in the United States alone—at a time in which revenues have plummeted to nothing, Dan Ashe, the president of the Association of Zoos and Aquariums, told me. In the United States, at least eighty per cent of zoos and aquariums accredited by the A.Z.A. are closed, which means no ticket sales, no merchandise bought for the kids, no stroller rentals, and no food sales, all of which contribute to both zoo programs and long-term conservation worldwide.

“The amount of losses through the whole zoological community is staggering,” Steven Monfort, the director of the Smithsonian’s National Zoo, in Washington, D.C., told me. “Most of us are trying to figure out how to get to the spring of 2021 and hope that there’s a vaccine or something so that visitation by then will be more normal.” With new social-distancing rules, most zoos expect to reopen eventually, but, at least initially, at roughly a quarter capacity—producing only a quarter of income, at best. “All of us have plans, but we don’t know how well those plans will work,” Monfort added.

Most U.S. zoos have laid off or furloughed up to half of their staffs, according to several zoos. In Portland, the Oregon Zoo has laid off a quarter of its staff, in addition to two hundred part-time employees. Sixty per cent of its revenue comes from ticket sales, but zoos generally operate on a seasonal basis, so, for nine months of the year, costs have long exceeded revenues. “If we can’t open, we will just run out of money by the end of September,” Sheri Horiszny, the Oregon Zoo’s deputy director, told me. “We won’t be able to operate as we have—possibly ever, and certainly for the immediate future.” The problem is global, she said. “Ninety per cent of the zoos on the planet were closed. Virtually all are now strapped—some are devastated.”

In northern Germany, the shuttered Neumünster Zoo has a wrenching contingency plan for its seven hundred animals if funding or the food-supply chain fail to help the facility survive. “If—and this is really the worst, worst case of all—if I no longer have any money to buy feed, or if it should happen that my feed supplier is no longer able to supply due to new restrictions, then I would slaughter animals to feed other animals,” Verena Kaspari told the German news agency Deutsche Presse-Agentur last month. The zoo made a list of which animals it would euthanize first, she said. The zoo is noted for its panda twins, penguins, and seals. The last to go, Kaspari said, would be Vitus, a snowy polar bear that stands twelve feet tall.

In Canada, two playful pandas at the Calgary Zoo—Da Mao and Er Shun—are being sent back to China. The zoo’s star attractions, they are the victims of another aspect of the pandemic: the disruption of food supplies. The zoo was able to stockpile and freeze fish for the penguins, horse meat for the large cats, and protein biscuits for the primates. But each panda eats eighty-eight pounds of fresh bamboo every day. Calgary used to get its fresh bamboo flown in from China, but then flights from China to Calgary stopped. The only remaining route was a weekly flight from China to Toronto, but the bamboo wasn’t fresh by the time it reached Calgary. The zoo started importing bamboo from California, but then flights stopped from there, as well. The zoo then tried trucking bamboo from the West Coast of the U.S. to Calgary, in central Canada, but the trucks stopped in Vancouver first, and, by the time they arrived in Calgary, the bamboo was spoiled. The zoo then hired a courier company to pick up the bamboo from Vancouver. But access to the airport took three days—and more shipments of the bamboo spoiled. Finally, the zoo began trucking in bamboo from Victoria, a region near Vancouver, but bamboo is not an indigenous plant, so the region couldn’t supply the quantity needed.

“Every ten days, there was a curveball,” Clément Lanthier, the C.E.O. and president of the Calgary Zoo, told me. “These are very precious animals. I can’t take the risk of having to tell my staff that the pandas could starve because bamboo won’t get here until tomorrow or next week. So it’s time for the pandas to go back home.” The pair arrived in Calgary only two years ago—after six years of planning and a twenty-one-million-dollar investment.

The food challenge is staggering for zoos everywhere. “People’s perceptions of zoos is that we just pick up poop,” Horiszny, from the Oregon Zoo, told me. The Portland zoo made changes early on when it realized food was an issue for the entire planet. “But imagine if you have a dinner party with six to ten guests, and one is lactose intolerant, another has a gluten allergy, and a third is philosophically vegetarian,” she said. “We have two thousand ‘guests’ from two hundred and twenty species with different dietary needs. So every day we have a challenge meeting those needs.”

The cost of animal care can also be staggering. In 2018, the San Diego Zoo and its sister Safari Park spent more than two hundred million dollars on operations to feed and care for its animals. The Oregon Zoo budgets more than a quarter million dollars just to care for Chendra, its Asian elephant, for six months. The zoo has an innovative program to save the Oregon silverspot butterfly from extinction. But it costs a hundred and twenty-six thousand dollars for nine months—for a horticulturist to tend to the thousands of violet plants in a greenhouse that provide food for twelve hundred silverspot caterpillars. A human also needs to keep the caterpillars clean, watered, and fed until they become adults and can be released, the zoo’s director, Don Moore, told me. “Yes, it’s very expensive to feed animals!” he e-mailed. Zoos also have heavy medical costs, from artificial insemination of endangered pandas to providing medication and surgery for ill or aging animals. Ashe, the A.Z.A. president, noted that veterinarians provide twenty-four-hour care to the animals at zoo facilities. “They get better health care than you or I do,” he said.

The National Zoo, in Washington, D.C., is losing more than a million dollars a month that it has no chance of recouping. Like other zoos, it launched a covid-19 emergency-response campaign for donations. “But there’s no way, no philanthropic answer, that will fill the bucket of needs,” Monfort told me. “The question is what happens in the longer run.” The Washington zoo also manages long-term research programs in twenty-five countries, in Asia, Africa, and Latin America. In 2018, American zoos, in total, contributed more than two hundred and thirty million dollars for field conservation worldwide—funds generated largely off ticket sales. “Without revenue coming in, it is challenging our members to find ways to keep up that commitment to conservation. We fear the bottom will fall out of that in 2020,” Ashe told me. “This dormant period is going to have a real impact on conservation in the field for animals,” ranging from elephants and giraffes to rhinos, manatees, orangutans, gorillas, and condors.

Zoos that qualify as small businesses—with fewer than five hundred employees—have applied for federal aid through the Payroll Protection Program. At least sixty per cent of the members of the Association of Zoos and Aquariums have won aid, Ashe told me. The current program covers payroll and other expenditures, but not animal care—and only for two months, through mid-June. Larger zoos—in San Diego, St. Louis, and the Audubon Zoo, in New Orleans—do not qualify. Others, in Cleveland and Little Rock, and the National Zoo, don’t qualify because of their ties to the government. Horiszny, of the Oregon Zoo, predicted that some zoos will never recover. “Virtually all are now strapped, some are devastated,” she said. “In natural disasters, some of those animals were sent to other zoos. Now there is nowhere to send an animal. Everyone’s in trouble.”

The pandemic has affected the behavior of animals, as well. Many species have demonstrated the same kinds of loneliness that people have. “It’s fair to say animals miss people as much as people miss animals,” Ashe, the A.Z.A. president, said. In zoos, humans offer a form of sensory stimulus to other species. Without them, the penguins, pandas, elephants, chimpanzees, and even camels and meerkats seem a little bored. “The variety of smells that come through the zoo every day are enrichment for them. Their day is less interesting or varied without us.” Some species—particularly elephants and great apes—notice the absence of humans. “They have strong bonds and enjoy interacting with guests and showing off,” Monfort, from the National Zoo, said. “When guests are not there, some tend to act a little needy.”

In Calgary, the normally nonchalant camels have been wandering up to the moat to interact with the few people still on site, while the gorillas come to the window when anyone passes by. “I walked by the meerkats in the Savannah building yesterday, and they ran right up to me,” Lanthier said. Chloe, the chimp matron at the Oregon Zoo, was so famous for kissing visitors (through a window) that the park hosted a kissing-booth party for her last year, when she turned fifty. She has been so lonely during the pandemic that keepers for other animals have been urged to call on her. “She was really craving attention,” Horiszny said. “The chimps, like us, are not experiencing life as usual.”

Last week, the Kansas City Zoo arranged for its three penguins to take a field trip to the local Nelson-Atkins Art Museum for a “morning of fine art and culture.” “We’re always looking for ways to enrich their lives and stimulate their days,” Randy Wisthoff, the zoo director, said, in a video posted on the museum’s Web site and the zoo’s Facebook page. “The penguins absolutely loved it.” The museum’s executive director, Julián Zugazagoitia, noted that the three Humboldt penguins “seemed to react much better to Caravaggio than to Monet.”

In Chicago, a Rockhopper penguin named Wellington has become an Internet sensation after the Shedd Aquarium posted videos of him hopping around other exhibits at the zoo. He now has his own hashtag, #whereswellington. He had a particularly winsome encounter, through a window, with a white beluga whale. They seemed fascinated with each other. The Chicago aquarium also let the sea lions roam around its administration offices. Zoos in Denver and Portland have let their pink flamingos wander along pathways where people once strolled. The Toronto Zoo took llamas and a donkey on an excursion to visit the polar bears.