Many animals have the same biological clock as humans. We rise after sunrise and settle after sunset while conducting our daily routines in between. Diurnal animals, like the sun bear, spend up to 80% of their time in the daylight.

However, when disturbed by humans, that schedule is strongly disrupted. According to a study published in June in the journal Science, in areas where sun bears are exposed to human activity, 90% of their waking time is spent in the dark. Incongruously, the sun bear has become nocturnal.

The sun bear has transitioned from a diurnal to a nocturnal lifestyle, now spending about 90% of its waking hours at night.

Along with the sun bear, their study included deer, tigers, boars, and 60 other mammal species.

Another study, led by scientists from Boise State University and the University of California-Berkeley, found that human activity is the driving source for mammals to shift their activity from the day into the dark hours of the night. Many animals have already been forced out of their natural habits due to human industrialization. Its evident animals are adjusting by attempting to avoid interaction with humans by “separating themselves in time rather than in space,” the study authors’ write.

Congruently, a lot of animals have flocked to more urban areas. It’s projected that six billion people will live in Urban areas by 2045. With the human impropriety in food waste, wild animals find more opportunities for feeding by staying close to humans. With that, these creatures find solace in urban areas as they are not exposed to as many hunters. Their desire to interact with us is a different situation.

Raccoons have long been familiar staples of urban and suburban life.

“We forget that we are the biggest cause of evolution on the planet right now,” says Suzanne MacDonald, a psychologist and biologist at York University in Toronto, Canada, who studies urban raccoons. MacDonald continues, “We have this view of the wild as a pristine place” and of evolution as something that happens “in the wild,” she says. “But humans in cities are changing the animals now. And with so many animals going urban, humans must view cities as part of—not separate from—nature,” adds MacDonald, a National Geographic grantee. “To live in harmony with animals whose habitat we’re destroying, we’re going to have to do a lot more work in what we’re doing to them.”

A great example, of wild animals in the concrete jungle, is the coyote. They will eat anything from leather to leftover food, although they prefer wild prey. These omnivores lurk at night and videos show they’ve likely learned to observe traffic patterns to figure out when to crossroads.

A coyote looks out at his kingdom in San Francisco.

Coyotes are also excellent at hiding. In downtown Chicago, one GPS-collared coyote pair raised a litter of five healthy pups inside a discrete concrete den in the parking lot of Soldier Field Stadium, home of the Chicago Bears.

Researches have warned us that the natural behavior patterns of so many species have been compromised and that the predator-prey dynamic has evolved over generations. “We really don’t know,” says lead author Kaitlyn Gaynor of UC Berkeley. “Entire ecosystems might be reshaped by this behavior.