Researchers have learned that dozens of species of animals have reacted to increased contact with human beings by shifting their internal clocks to become more nocturnal. “It suggests that animals might be playing it safe around people,” study leader Kaitlyn Gaynor told “We may think that we leave no trace when we’re just hiking in the woods, but our mere presence can have lasting consequences.” In a new study published in the journal Science, Gaynor and her team analyzed data from 76 previous studies on 62 different animal species spread out over six continents and concluded that even relatively low-impact activities can affect animal behavior.

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Animals featured in this study, many of whom were mammals, include coyotes in California, wild boars in Poland, lions in Tanzania, tigers in Nepal, and otters in Brazil. To determine the effect of human behavior on sleeping patterns, researchers determined how long animals were active at night when affected by different kinds of human activities, such as hunting, hiking, and farming. The team concluded that human presence correlated with a 20 percent increase on average of nocturnal activity among the animals studied.

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This research is among the first to explore and quantify how human behavior impacts animal activity and sleep patterns on a broad scale.  “No one else has compiled all this information and analyzed it in such a … robust way,” researcher Ana Benitez Lopez, who reviewed the study, told The study is a reminder that simply being in a wild space can fundamentally change it. “It’s a little bit scary,” ecologist Marlee Tucker, who did not participate in the study, told “Even if people think that we’re not deliberately trying to impact animals, we probably are without knowing it.” While some animals will struggle with adapting to night life, the shift may also provide benefits to animals who hope to share space with humans without ever dealing with them. Armed with new knowledge, I will nonetheless continue to hike and camp, because it helps me sleep.


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