Birds and people flock to Stora Karls, an island off the coast of Sweden, in the spring.

The tourist season was canceled in 2020 due to the Covid-19 Pandemic. Researchers found that white-tailed eagles became more abundant when people were out of the picture.

It might seem like a simple parable about how nature recovers when people leave the landscape, but it's not. The eagles flew past the cliffs where a protected population of common murres lay their eggs.

Some eggs fell from the cliffs while others were snatched by the predator. The breeding performance of the murres decreased by 26 percent. He said that they lost their eggs.

A global human tragedy was caused by the Pandemic. It has been an unparalleled opportunity for ecologists to learn more about how people affect the natural world when we step back from it.

The slow down of human activity has become known as the "anthropause" because of a growing body of literature. Our absence was consistent with media narratives that nature was healing. Other species were not protected or provided with resources.

A scientist at the University of Victoria said that humans are playing two roles. She said that we are both threats to wildlife and caretakers of the environment.

Scientists say that the research shows that even modest changes in human behavior can have a bigger impact on other species. As the human world roars back to life and summer travel surge, those shifts may be important to consider.

Christian Rutz, a behavioral ecologist at the University of St Andrews, introduced the concept of an "anthropulse" in a recent paper. They were part of the team that came up with the term "anthropause".

He said that humans should enjoy nature. It can be subtle changes to how we do things that can still have a big impact.

ImageMurres in Stora Karlsö, a nature reserve off the coast of Sweden.
Murres in Stora Karlsö, a nature reserve off the coast of Sweden.Credit...Aron Hejdstrom
Murres in Stora Karlsö, a nature reserve off the coast of Sweden.
ImageA white-tailed eagle buzzing murres in the waters off Stora Karlsö.
A white-tailed eagle buzzing murres in the waters off Stora Karlsö.Credit...Aron Hejdstrom
A white-tailed eagle buzzing murres in the waters off Stora Karlsö.

Many human routines were halted when the Pandemic hit. Almost half of the world's population were under some sort of restriction on April 5, 2020. Driving and air traffic both went down.

Researchers were able to tease out the effects of human travel from other ways we shape the lives of other species.

Christopher Wilmers is a wildlife ecologist at the University of California, Santa Cruz. What are the effects of human mobility itself?

Air and water quality improved in some places when people were holed up in their homes. There was a reduction in noise pollution under the sea. The human-disturbed habitats started to recover.

The Hanauma Bay Nature Preserve was closed for nine months in 2020. The visitor impacts were reset to zero by the Pandemic.

Dr. Rodgers and her colleagues found that the clarity of the water had improved. The waters used to be thick with snorkelers.

ImageHanauma Bay in Hawaii was closed in July 2020. During its nine-month closure, water clarity improved in the absence of snorkelers.
Hanauma Bay in Hawaii was closed in July 2020. During its nine-month closure, water clarity improved in the absence of snorkelers.Credit...Youli Zhao/Alamy
Hanauma Bay in Hawaii was closed in July 2020. During its nine-month closure, water clarity improved in the absence of snorkelers.

Many species moved into new habitats as the landscape of fear changed.

All animals are trying not to die, according to an ecologist. They have a drive to survive that makes them keep their distance. Dr. Gaynor said that they are noisy and novel and similar to their predator.

The mountain lions in the Santa Cruz Mountains of California don't like to go to the city. The animals were more likely to choose habitats near the urban edge after local shelter-in-place orders were implemented.

Dr. Wilmers thought that the mountain lions were responding to changes in the city's urban sound system, which might be filled with human chatter and the rumble of passing cars. The animals will go see if there is anything to eat when the audio stimuli are over.

White-crowned sparrows began singing more quietly in San Francisco, yet the distance they could communicate more than doubled.

The birds began singing at lower frequencies, which is associated with better performance and an improved ability to defend territory. According to Elizabeth Derryberry, an author of the study, their songs were more sexy.

She said it was an overnight event. If you reduce noise levels in an area, you can have a positive impact.

ImageA mountain lion found dead along Route 101 in Calabasas, Calif., in September 2020.
A mountain lion found dead along Route 101 in Calabasas, Calif., in September 2020.Credit...California Highway Patrol, West Valley Division, via Associated Press
A mountain lion found dead along Route 101 in Calabasas, Calif., in September 2020.
ImageA predatory mouse near an albatross on Gough Island in the South Atlantic.
A predatory mouse near an albatross on Gough Island in the South Atlantic.Credit...Royal Society for the Protection of Birds
A predatory mouse near an albatross on Gough Island in the South Atlantic.

The effects of human absence were varied.

The number of wild animals that were struck and killed by cars decreased in the spring of 2020. Even though traffic remained below normal levels, the number of wildlife-vehicle collision crept back up.

According to an author of the study, there were more accidents per mile driven during the Pandemic. Animals began to use roads. It was difficult for them to stop.

In Italy, the daytime activity of Eastern cottontail rabbits increased due to the fact that their rapid expansion may threaten native hares. The project to kill giant, predatory mice from Gough Island, a critical habitat for threatened sea birds in the South Atlantic Ocean, was put on hold because of the swine flu.

The mice, who arrived with 19th-century sailors, attack and feed on birds and leave large open wounds. "I nicknamed them 'vampire mice' because they were so aggressive," said the environmental and policy officer for the archipelago. Many birds are injured.

The project was delayed for a year because of the Pandemic. Not one MacGillivray's prion chick survived the intervening breeding season because of the vampire mice. The other breeding season was lost. It meant more of the same with no new faces.

Humans took the mice to Gough because it was the only place they could live. Humans need to kill them.

She said that these types of impacts were added up all over the world. There were spikes in illegal logging and mining in many countries.

Some of this activity may have been driven by economic insecurity, but experts believe that it was also made possible by a lack of tourists and reduced staffing in parks and preserves.

A research assistant at the University of Victoria says they are not the bad guys. We are doing a lot better than we have been giving ourselves credit for.

ImageTourists to the Greek island of Zakynthos have appeared to drive sea turtles away from the warmer waters close to shore.
Tourists to the Greek island of Zakynthos have appeared to drive sea turtles away from the warmer waters close to shore.Credit...Gail Schofield
Tourists to the Greek island of Zakynthos have appeared to drive sea turtles away from the warmer waters close to shore.

Researchers will continue to monitor wildlife as people return to their normal lifestyles. Stronger evidence of our impact will be provided when people come flooding back.

It is a reversal of the experimental or semi-experimental intervention that scientifically allows robust insights into how environmental processes work.

Experts can use these mechanisms to channel our influence more thoughtfully.

"If we strengthen the role as custodians and then continue to regulate pressures, then we can really tilt the role of humans in the environment to an overwhelmingly positive role."

One team of researchers found that with vacationers not traveling to the Greek island of Zakynthos in the summer of 2020, the loggerhead sea turtles that nest there spent more time close to shore in the warmer waters that are optimal for female egg development than they had in the past.

The results suggest that tourists are driving sea turtles into cooler waters, slowing egg development and possibly reducing the number of clutches, or batches of eggs, the animals lay.

She said that the window of opportunity was very small.

She acknowledged that it's not possible to stop all tourism. She said that designating a stretch of the shoreline as a turtle habitat and prohibiting swimming there in the early summer could be an important refuge for the animals.

The Hanauma Bay Nature Preserve instituted a cap on the number of visitors. It is now open two days a week, up from one before the Pandemic.

Building wildlife crossing over highways could keep animals from becoming road kill, while mandating quieter car engines and boat propellers could reduce noise pollution.

We can change the world in a year because we are able to. We did, that's what we said.