To Avoid Humans, More Wildlife Now Work The Night Shift


Published:

Red fox under cover of darkness in London. (For use only with this article.)

© Jamie Hall

For their first 100 million years on planet Earth, our mammal ancestors relied on the cover of darkness to escape their dinosaur predators and competitors. Only after the meteor-induced mass extinction of dinosaurs 66 million years ago could these nocturnal mammals explore the many wondrous opportunities available in the light of day.

Fast forward to the present, and the honeymoon in the sun may be over for mammals. They’re increasingly returning to the protection of night to avoid the Earth’s current terrifying super-predator: Homo sapiens.

My colleagues and I have made the first effort to measure the global effects of human disturbance on the daily activity patterns of wildlife. In our new study in the journal Science, we documented a powerful and widespread process by which mammals alter their behavior alongside people: Human disturbance is creating a more nocturnal natural world.

Many catastrophic effects of humans on wildlife communities have been well-documented: We are responsible for habitat destruction and overexploitation that have imperiled animal populations around the world. However, just our presence alone can have important behavioral impacts on wildlife, even if these effects aren’t immediately apparent or easy to quantify. Many animals fear humans: We can be large, noisy, novel and dangerous. Animals often go out of their way to avoid encountering us. But it’s becoming more and more challenging for wildlife to seek out human-free spaces, as the human population grows and our footprint expands across the planet.

Global Increase In Nocturnality

My collaborators and I noticed a striking pattern in some of our own data from research in Tanzania, Nepal and Canada: animals from impala to tigers to grizzly bears seemed to be more active at night when they were around people. Once the idea was on our radar, we began to see it throughout the published scientific literature.

 A badger explores a South London cemetery at night. © Laurent Geslin (For use only with this article.)It appeared to be a common global phenomenon; we set out to see just how widespread this effect was. Might animals all over the world be adjusting their daily activity patterns to avoid humans in time, given that it is becoming harder to avoid us in space?

To explore this question, we conducted a meta-analysis, or a study of studies. We systematically scoured the published literature for peer-reviewed journal articles, reports and theses that documented the 24-hour activity patterns of large mammals. We focused on mammals because their need for plenty of space often brings them into contact with humans, and they possess traits that allow for some flexibility in their activity.

We needed to find examples that provided data for areas or seasons of low human disturbance – that is, more natural conditions – and high human disturbance. For example, studies compared deer activity in and out of the hunting season, grizzly bear activity in areas with and without hiking, and elephant activity inside protected areas and outside among rural settlement.

Based on reported data from remote camera traps, radio collars or observations, we determined each species’ nocturnality, which we defined as the percentage of the animal’s total activity that occurred between sunset and sunrise. We then quantified the difference in nocturnality between low and high disturbance to understand how animals changed their activity patterns in response to people.

For each species, researchers compared the animals’ active periods when people are nearby to when people aren’t around. The distance between the grey and red dot pair for each animal shows how extreme the shift in nocturnality. Reprinted with permission from Gaynor et al., Science 360:1232 (2018). For use only with this article.

Overall, for the 62 species in our study, mammals were 1.36 times as nocturnal in response to human disturbance. An animal that naturally split its activity evenly between the day and night, for example, would increase its nighttime activity to 68 percent around people.

While we expected to find a trend toward increased wildlife nocturnality around people, we were surprised by the consistency of the results around the world. Eighty-three percent of the case studies we examined showed some increase in nocturnal activity in response to disturbance. Our finding was consistent across species, continents and habitat types. Antelope on the savanna of Zimbabwe, tapir in the Ecuadorian rainforests, bobcats in the American southwest deserts – all seemed to be doing what they could to shift their activity to the cover of darkness.

Perhaps most surprisingly, the pattern also held across different types of human disturbance, including activities such as hunting, hiking, mountain biking, and infrastructure such as roads, residential settlement and agriculture. Animals responded strongly to all activities, regardless of whether people actually posed a direct threat. It seems human presence alone is enough to disrupt their natural patterns of behavior. People may think our outdoor recreation leaves no trace, but our mere presence can have lasting consequences.

Future Of Human-Wildlife Coexistence

We don’t yet understand the consequences of this dramatic behavioral shift for individual animals or populations. Over millions of years, many of the animals included in our study have evolved adaptations to living in the daylight.

 Sun bears retreat from the sunny hours when people are nearby.Sun bears, for example, are typically diurnal and sun-loving creatures; in undisturbed areas less than 20 percent of their activity occurred at the night. But they increased their nocturnality to 90 percent in areas of the Sumatran forest where intensive forest research activity created a disturbance.

Such diurnally adapted animals may not be as successful at finding food, avoiding predators or communicating in the darkness, which could even reduce their survival or reproduction.

However, because our mammalian ancestors evolved under the cover of darkness in the time of the dinosaurs, most mammal species possess traits that allow for some flexibility in their activity patterns. As long as animals are able to meet their needs during the night, they may actually thrive in human-dominated landscapes by avoiding daytime direct encounters with people that could potentially be dangerous for both parties. In Nepal, for example, tigers and people share the exact same trails in the forest at different times of day, reducing direct conflict between humans and these large carnivores. Dividing up the day, through what researchers call temporal partitioning, may be a mechanism by which people and wildlife can coexist on an ever more crowded planet.

An increase in nocturnality among certain species may also have far-reaching consequences for ecosystems, reshaping species interactions and cascading through food webs. In California’s Santa Cruz Mountains, coyotes are becoming more nocturnal in areas with human recreation. By analyzing coyote scat, scientists have linked this behavioral change to dietary shifts from diurnal to nocturnal prey, with implications for small mammal communities and for competition with other predators.

Working on this study reminded me that people aren’t alone on the planet. Even if we don’t see large mammals while we’re out and about during the day, they may still be living alongside us, asleep while we are awake and vice versa. In areas where threatened species live, managers may consider restricting human activity to certain times of the day, leaving some daylight just for wildlife.

And it is likely that we need to preserve wilderness areas entirely free of human disturbance to conserve the most vulnerable and sensitive mammal species. Not all animals are willing or able to just switch to a nocturnal lifestyle around people. Those that try to avoid human disturbance entirely may be most vulnerable to the consequences of the expanding human footprint.

Kaitlyn Gaynor, Ph.D. candidate in environmental science, policy and management at the University of California, Berkeley is a wildlife ecologist and conservation scientist. Kaitlyn is interested in better understanding the socio-ecological dynamics of ecosystems to promote human-wildlife coexistence. Her research draws on behavioral and community ecology to understand the roles that humans play in ecological systems, and how humans interact with other large mammal species in shared spaces.

This article was originally published on The Conversation. Read the original article.

See also:
Animals To Humans: Be Quiet, Already
Animals And Plants Evolve Faster In Cities — With Implications For Humans

The Conversation

Edit Module
Edit ModuleShow Tags
Edit Module Edit ModuleShow Tags

Daily Astrology

July 21, 2018

Soothing trends make for sound sleep and good dreams. Night owls find themselves pleasantly wandering between worlds of dreamy idealism and creative inspiration. As the new day dawns the Scorpio Moon is harmonizing with Pluto in Capricorn. Chores are…
Edit ModuleShow Tags

Alternative Health Directory

Browse all listings »

Edit ModuleShow Tags
Edit ModuleShow Tags

Calendar

July 2018

Join us for a monthly gathering of like-hearted people to give and receive angelic energy healing. This session is a combination of group meditation and discussion, along with working in pairs...

Cost: Scale $5-$20 ($10 suggested)

Where:
Pathway Of Joy
884 Broadway, Suite 12
Upstairs in the Spiritual Renaissance Center building
South Portland, ME  04106
View map »


Sponsor: Pathway Of Joy
Telephone: 207-329-7192
Contact Name: Linda Huitt
Website »

More information

Show More...
Show Less...

This special 2-part evening offering. Earn your Integrated Energy Therapy® certification in two evenings, while leaving your summer days and weekends open to enjoy the season. Part 1 is...

Cost: $195

Where:
Pathway Of Joy
884 Broadway, Suite 12
South Portland, ME  04106
View map »


Sponsor: Pathway Of Joy
Telephone: 207-329-7192
Contact Name: Linda Huitt
Website »

More information

Show More...
Show Less...

What better way to end a busy day than with a little bliss. We'll support your body right where it is today and help you to open your spine to find more movement and flexibility. Begin and end...

Cost: $18

Where:
Body Love Wellness Center
484 Bedford St
East Bridgewater, MA  02333
View map »


Sponsor: Bliss Through Yoga
Telephone: 508-331-3564
Contact Name: Janice
Website »

More information

Show More...
Show Less...

Relax and restore this summer with free outdoor yoga classes on historic Rogers Field! We’re packing the lawn with yogis of all levels for yoga led by experienced practitioners from Dragonfly...

Cost: Free

Where:
Rogers Field
Devens, MA


Sponsor: Dragonfly Wellness Center
Telephone: 978-487-7181
Contact Name: Anne Ferguson
Website »

More information

If you are worried about getting Parkinson’s or have beginning symptoms, check out a free intro on how to rewire your brain from the inside. First and third Wednesdays of the month,...

Where:
, MA


Website »

More information

Show More...
Show Less...

Please note this event is held at an off-site location at the Double Tree Hilton in Danvers, MA There will be a book signing following the mediumship demonstration, and as part of your ticket...

Cost: $45

Where:
Double Tree Hotel
50 Ferncroft Road
Danvers, MA  01923
View map »


Sponsor: Circles of Wisdom
Telephone: 978-474-8010
Contact Name: Cathy Kneeland
Website »

More information

Show More...
Show Less...

July 20 - 22 The Chinese internal martial arts derive their extraordinary power from the conscious control of one’s subjective state-of-being and the use of jin (internal power)....

Cost: Please see our website

Where:
Eastover Estate & Retreat Center
430 East St.
Lenox, MA  01240
View map »


Telephone: 866-264-5139
Contact Name: Yingxing Wang
Website »

More information

Show More...
Show Less...

The mission of the 4th Annual Compassionfest is to unite like-minded people that believe in the values of being just, kindness, equality and compassion. We’ll gather for delicious vegan food...

Cost: Free

Where:
Whitneyville Cultural Commons
1253 Whitney Ave
Hamden, CT  06517
View map »


Sponsor: In Defense of Animals
Website »

More information

Saturday, July 21, 10:00am – 4:00pm & Sunday, July 22, 10am – 4:00pm With Patty Collinsworth Get the beginner certification before Linda Howe comes in person to teach a new...

Cost: $170

Where:
Circles of Wisdom
90 Main Street
Andover, MA  01810
View map »


Sponsor: Circles of Wisdom
Telephone: 978-474-8010
Contact Name: Cathy Kneeland
Website »

More information

Saturday, July 21, 10:00am – 5:30pm & Sunday, July 22, 10am – 3:30pm Instructor:  Peyton Pugmire What brings you joy and a sense of purpose?  These are your soul...

Cost: $160

Where:
Creative Spirit
80 Washington Street
Marblehead, MA  01945
View map »


Sponsor: Creative Spirit
Telephone: 617-817-4547
Website »

More information

July 21 - 22 NEMHoFest, is New England’s premiere metaphysical festival. This year’s line-up includes world renowned guest speakers and vendors from across the...

Where:
Augusta Civic Center
Augusta, ME


Website »

More information

The GFAF Expos are the greatest events on earth for those living a gluten-free or allergen-friendly lifestyle. Sample hundreds of products, meet with local and national brands, receive coupons and...

Where:
DCU Center
50 Foster Street
Worcester, MA
View map »


Website »

More information

Show More...
Show Less...
Edit ModuleShow Tags
Edit Module Edit ModuleShow Tags