A recent study in Glacier National Park showed that only one species of wildlife, red foxes, demonstrated an effect known as “human shielding,” which is when human presence causes large predators to avoid an area, providing an opportunity for smaller predators to use it more frequently.

One of the best things about spending time in nature is spotting animals in their natural habitats, seemingly going about their lives as if we weren’t watching. It’s those brief glimpses into the wild that our souls seem to crave. And since the COVID-19 pandemic outbreak, especially, our desire for more outdoor recreation has been skyrocketing.

But what we probably don’t realize is that even though the animals we see appear to be going about the business of making their livings just as if we weren’t there, we are still having an impact on them—and a bigger one than any of us probably ever imagined. In fact, we can have major effects on wildlife just by being nearby.

One 2021 literature review, for example, found that birds and small mammals may change their behavior—including leaving an area or spending less time feeding—when people get within 300 feet (the length of a football field). Large birds, such as eagles and hawks, can be affected when humans are more than 1,300 feet away, or approximately a quarter of a mile. For large mammals, such as elk and moose, humans up to 3,300 feet (more than half a mile) away can alter what an animal does.


Even without hunting rifles, humans appear to have a strong negative influence on the movements of all wildlife. Small mammals, such as this Columbian ground squirrel, may change their behavior when people get within 300 feet.

So, how do we balance our healthy urge for spending more time outdoors and in nature with our wish to disrupt wildlife as little as possible?

Avoidance activity

Glacier National Park, which covers nearly 1,600 square miles of northwestern Montana, hosts more than 3 million human visitors a year. It is also home to a diverse range of wild animals, with almost the full complement of mammal species that has existed in the region historically.

An intriguing study that was conducted in the park, published in the journal Scientific Reports on January 13, 2023, came about in part because of the pandemic. Both humans and wildlife like to use trails, so Washington State University and National Park Service researchers set up an array of camera traps near several footpaths to study lynx populations in the park when COVID-19 hit. To keep the virus from spreading to the nearby Blackfeet Indian Reservation, the eastern portion of the park was closed in 2020 with only minimal access allowed to administrators and researchers.


Eagles are prone to be affected when humans are as much as 1,300 feet away, or approximately a quarter of a mile.

This allowed the scientists to conduct a natural experiment. They captured images by camera traps in summer of 2020 when the park was partially closed due to COVID-19 restrictions, as well as in 2021 when the park reopened and experienced high visitation rates. When they compared the two sets of data, the researchers found that when human hikers were present, 16 out of 22 mammal species—including predators and prey alike—changed where and when they accessed areas. Some completely abandoned places they previously used, others used them less frequently, and some shifted to more nocturnal activities to avoid humans.

Because Glacier National Park is so highly protected, the results surprised the scientists. Since there’s no other measurable human disturbance out there, these responses, then, must be driven by human noise and human presence alone.

The researchers had also expected to find an effect known as “human shielding,” when human presence causes large predators to avoid an area, providing opportunity for smaller predators and, perhaps, some prey species to use an area more frequently. In this case, they found this potential effect for only one species, red foxes. The foxes were more present on and near trails when the park was open; perhaps because their competitors, coyotes, avoided those areas when humans were around.


Humans more than half a mile away might change the behavior of a moose.

Trail treatments

When the park was open, the study revealed that several species showed a decline in use of trail areas, including black bears, elk and white-tailed deer. Many decreased their daytime activities, including coyotes, grizzly bears, mule deer and snowshoe hares. A few, including cougars, seemed indifferent to human presence.

While the influence of low-impact human recreation is concerning, the researchers emphasized that more research is needed to determine if it has negative effects on species’ survival. They state that their study does not show that even “silent sports”—such as hiking—are necessarily bad for wildlife, but they do have some impacts on spatiotemporal ecology, or how wildlife uses landscapes and when. For example, animals may not be on the trails as much, but they could be utilizing different places. How much that makes a difference in animals’ ability to survive and thrive in a location is not yet known.

Difficult dilemma

This sets up a quandary for ecotourists: how do we balance the harm our mere presence could be causing wildlife with the good our animal adventures create?


A study in Glacier National Park found that when human hikers were present, 16 out of 22 different mammals changed how they accessed areas.

Ultimately, what we should be striving for is a net benefit to the planet and its wildlife. And there’s no doubt that conservation travel brings value to natural habitats and the wildlife that lives in them. According to a World Bank Report, two of the top five motivators for selecting vacation spots are ecotourism and nature. Travelers are seeking experiences that reflect the true essence of the places they are visiting; they want to experience locations with unspoiled environments and thriving, native animals.

Today, wildlife tourism supports nearly 22 million jobs around the world and contributes more than $120 billion to the global GDP (gross domestic product). This burgeoning interest in wildlife tourism—and the economic benefits that come with it—can change local attitudes toward conservation. Without tourism, people may view wild animals as a danger to their families and farms and only as natural resources for consumption. But when animals and natural areas bring tourism dollars and jobs to a community, residents see the importance of keeping their natural assets intact and healthy.


When Glacier National Park was reopened after the COVID-19 pandemic, black bears used trail areas less than they did when human visitation was restricted.

Creating nature ambassadors is another weight on the scale measuring ecotourism’s net benefit to the planet. Court Whelan, Natural Habitat Adventure’s chief sustainability officer, puts it this way:

“Many conservation crusaders were sparked by an affinity for nature, which is the direct result of experiencing it firsthand. You simply cannot save what you do not love, and you cannot love what you do not know. We’re in the business of getting people to know Mother Nature. So, yes, it’s hard for us humans to walk out our doors and not have some sort of impact on the world. That’s true of driving to the grocery store as much as it is observing an animal in its natural habitat. That animal knows you’re there and may act differently because of it. But when you are ultra dialed into animal behaviors and knowledgeably work to minimize your impact on them—while at the same time adding economic value to their regions and thus creating new stakeholders—you are doing nature and wildlife a service.”

Best balance

Here are some simple actions you can take to minimize your impacts on wildlife:

1) Keep your distance. Although some species or individual animals will become used to human presence at close range, many others won’t. And it can be hard to tell when you are stressing an animal and potentially endangering both of you. Use binoculars or a zoom lens on your camera if you wish to have a more intimate encounter.


Sometimes, it’s harder for animals to detect quiet humans. Wildlife might be more surprised by a cross-country skier than a snowmobile.

2) Respect closed areas and stay on trails. For example, in Maine’s Acadia National Park, rangers annually close several trails near peregrine falcon nests. This reduces stress to nesting birds and has helped this formerly endangered species recover.

Generally, larger animals need more distance, though the relationship is clearer for birds than mammals. It’s thought for birds, as size increases, so does the threshold distance. The smallest birds can tolerate humans within 65 feet, while the largest birds have thresholds of roughly 2,000 feet. And a growing body of evidence shows that amphibians and reptiles are disturbed and negatively affected by human recreation. So far, however, it’s unclear whether those effects relate to the distance from people, the number of visitors or other factors.

3) Support wildlife corridors. As human developments fragment natural habitats and climate change forces many species to shift their ranges, movement passageways between protected areas become even more important. Creating recreation-free wildlife corridors that are at least 3,300 feet wide can enable most species to move between protected areas without disturbance.


In Maine, rangers at Acadia National Park close several trails near peregrine falcon nests each year. This helps this Atlantic Coast retreat and refuge ensure that stress to nesting birds is reduced as much as possible.

The recent pandemic has put the balancing act between our desire to spend time in nature and animal welfare in the spotlight. While it’s important that everyone has opportunities to get “out there,” there’s a level at which that could start to become problematic.

But facts and science are power. Knowing how much even our presence affects wildlife means that, in the moment, we can take precautions like those mentioned above to lessen our impact—all the while laying the groundwork for the long-term protection of the wild animals we love to watch.

Here’s to finding your true places and natural habitats,