Night shift: Animals are retreating into the darkness out of fear of humans

Foxes are adaptable critters that can function well in darkness and daylight. This one was caught on a critter camera on the Warm Springs Mesa.
Foxes are adaptable critters that can function well in darkness and daylight. This one was caught on a critter camera on the Warm Springs Mesa. Statesman file

As human beings expand their global footprint, taking more space from nature, animals are responding by escaping into new territory – the night.

The encroachment of humans, through development and light, is forcing animals away not just in distance, but in the time of day they are active.

This survival strategy can work well for adaptable animals — think coyotes — but not others. Many mammals that evolved for daytime operation can only become so nocturnal and scientists are concerned about the long-term effects.

“If you asked me ‘You have to get up at 2 a.m. and you have to do all the things you normally do’, I would probably revolt,” said Neil Carter, an assistant professor in Boise State University’s College of Innovation and Design. “It’s just not going to happen.”

In a recent study, published in the journal Science, Carter and his colleagues found that this night shift is affecting animals worldwide. “Elephants to possums to elk, which was astounding,” says Carter.

Idaho, it turns out, offers an optimal lens with which to view this research. Low population density, rapid growth, and ample wildlife near urban areas all converge here, making the state more sensitive to this issue than most.

But Idaho is also in a better position to do something about it, with growth and major effects just beginning. This gives Idahoans a chance to build their communities in more thoughtful ways. “We are in a very unique, interesting and cool part of this story,” says Carter.


As the head of BSU’s Conservation and Coexistence Group, Carter is primarily interested in how humans and wildlife try and live together.

Humans and animals alike must decide how to divvy up the day. We make choices about when to eat, when to sleep, when to work.

Imagine getting a new job, one in which you must work a graveyard shift instead of the usual 9-to-5. This new schedule will inevitably alter the way you operate and interact with the world.

Maybe the sandwich shop where you usually eat is no longer open when you’re awake and you’re forced to find a new place. Perhaps you have to do your shopping before you head to work instead of after. You might have to black out your windows or wear earplugs to sleep.

These choices won't just influence individual behavior. “It’s a top-down pressure on the whole ecosystem,” says Carter.

If enough people change to graveyards, they put pressure on those shop owners to change their business hours to accommodate, forcing them to change their habits and their employees' habits as well. It's a cascade effect.

So, what is driving this behavior shift in animals? Fear of humans, most likely, says Carter.

Lethal interactions, like hunting, obviously change the way animals interact with us. This type of interaction has a large body of work devoted to understanding it and is the foundation of much of our existing ecological efforts.

Non-lethal effects, such urban expansion, agriculture, and even our presence on hiking trails appear to be more far-reaching, altering the behavior of entire populations. It’s changing animals' access to food, their relationship to predators, and likely elevating their levels of stress. How this will play out in the long term is not well understood.

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A coyote stands in a field in this February 2013 photo. USDA Wildlife Services removes and kills millions of coyotes and other animals each year on behalf of ranchers, farmers, homeowners and airport operators. Karen Nichols Daily Inter Lake/AP file

Some animals can adapt very well. Coyotes are the quintessential example: They can eat pretty much anything and can be active at any time. Some predators can use the increased light from human development to hunt more effectively. Certain prey species can, in turn, use that same light to avoid hunters.

Not all animals are up to the task.

Cougars in urban areas in California and elsewhere, for instance, are killing more prey but becoming spooked by human interaction and leaving the kills uneaten. They are using more energy to get less.

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A mountain lion is captured by a wildlife camera in the Santa Margarita Ranch on Sept. 14, 2015. The Land Conservancy of SLO County

Stress is a huge factor as well. Persistent fear can elevate stress hormones, which are detrimental to the health of the animals. Imagine the uneasy feeling you get walking down a dark alley and being unsure of your safety. Now imagine having that feeling almost continuously. Large predators, such as lions, typically meander through their territory looking for prey. In human-influenced areas, however, they are moving faster and in straight lines, like a person bee-lining to their vehicle in a dark parking lot.

Carter is quick to point out, however, that extensive testing is needed to understand how this continued stress will affect wildlife. “We just don’t know yet what the consequences are."

What can Idahoans do?

Carter urges people to give more thought to what they are doing at night. What kind of noise sources are we contributing? What about pets and livestock outside that may frighten wildlife?


One major point is thinking about light. Idaho is in a unique position in that much of the state is generally dark. Central Idaho is home to the Dark Sky Reserve, one of 12 worldwide sites designated by the International Dark Sky Association for its pristine darkness, and the only such site in the United States. Due to this darkness, says Carter, even a small change in light can have a disproportionate effect on wildlife.

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Slooh, a Connecticut-based online observatory group, sets up telescopes for celestial viewing near Stanley late one night in August 2017. The group was among those in the area for this summer’s eclipse, to take advantage of its dark skies and lack of light pollution. Katherine Jones Idaho Statesman file

LED lighting is meant to be more efficient and cost-effective. However, as the cost comes down, cities are using more of it, increasing the overall brightness of urban areas. A recent article in Science Advances estimates that from 2012 to 2016, the area of the world’s artificially lit regions increased 2.2 percent per year and brightened by the same amount.

This type of lighting also has a broad color spectrum. This is good for humans, but can give false cues to wildlife, tricking them into thinking that dawn is approaching.

Luckily, it’s easy for people to turn off outdoor lights when possible or to change them out for more wildlife-friendly bulbs and shades.

Carter urges people to become involved in the growth-planning process. “Boise is going to grow really fast and what is that going to look like?” he asks. “We can keep protecting animals in space and time that other places in the country can’t do.”

“What are we willing to lose if we build something?”

Kevin Davenport: 208-377-6411, @tropnevaDniveK