A new study of 62 species of mammal from around the world has shown that not since the dinosaurs roamed the earth have mammals been so nocturnal. Researchers out of Boise State and UC Berkeley analyzed dozens of studies from around the globe, almost all from this century, and discovered that humans are clearly driving mammals into the shadows.
They found that mammal nocturnality increased by a factor of 1.36 in areas or periods with high human disturbance. This means that if an animal normally split its activity evenly between day and night, human activity is associated with an increase in the animals' proportion of nighttime activity to 68 percent. This was true across the board, for small mammals like opossums and large ones like African elephants; for apex carnivores as well as their prey; in Argentina and California and Zimbabwe and Nepal and Poland and everywhere else they looked.
Kaitlyn Gaynor is one of the authors on the study, and spoke with The Guardian.
“Humans are now this ubiquitous terrifying force on the planet and we are driving all the other mammals back into the night-time,” she said.
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“It is likely that we are going to need to preserve wilderness areas that are entirely free of [human] disturbance to protect really vulnerable species, and for species that can’t shift their activity to the night-time or where increased nocturnal activity is having negative consequences, we may need to restrict human activity to certain times of the day so we leave some daylight hours for animals to do their thing,” she said.
More work is necessary to figure out exactly what can be done to alleviate this clear stress on the animal kingdom. But pulling ourselves out of the “food-chain” has been both our biggest success and greatest failure in the survival of the human species.