Some Animals Switching To Nocturnal Life

Jun 24, 2018
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SUSAN DAVIS, HOST:

If you go to great lengths to avoid human interaction, you are not alone. A new study published in Science magazine shows that animals are changing their sleep schedules to prevent human contact. Instead of sleeping at night, some animals are switching to a nocturnal lifestyle. Neil Carter is a co-author on the study, which was led by researchers at the University of California at Berkeley. He's also an assistant professor at Boise State University. And he joins us now from KBSX in Boise. Welcome to the program.

NEIL CARTER: Thanks.

DAVIS: So I have to ask, on behalf of humans, was it something that we did?

CARTER: It appears that it is something that we did. It looks like it's a whole bunch of things that we've been doing, from agriculture to development to hunting to even just hiking and walking. All of these things appear to be disturbances that are affecting many different wildlife species around the world.

DAVIS: What kind of animals are you talking about?

CARTER: We're talking about mammals over 1 kilogram, or 2 and a half pounds, in size, so that's something like a possum, all the way up to a mammal as large as an African elephant. So very different kinds of mammal species.

DAVIS: And you studied tigers in Nepal? What did you see there?

CARTER: Yeah. So I studied. tigers in Nepal during my Ph.D., and, in fact, that was sort of my introduction to this topic and this idea. So there we were interested in how people going into the forests were affecting the behavior and activities of tigers. And we found - right away we saw this really interesting effect where areas that had a lot more human presence - just walking through the forests - tigers were becoming almost entirely active at night - still using the same places but being there active at night in order to avoid contact and encounters with people. So from that, you know, I think that there are a number of different implications. But one thing that we took away from it was a positive or optimistic outlook, which is this is a possible way for people and tigers to avoid negative encounters with each other because every so often, they do run into each other. And that's usually bad for one and usually both of them.

DAVIS: Sleep seems to be, for all mammals, a core issue of existence. In other words, if you change the way you sleep, does it change the way you do other things?

CARTER: Yeah. So changing the way you sleep is certainly one dimension of this work. If you're changing when you sleep, then other activities that you do are being shifted, as well. So take, for example, an animal that tends to look for food, for prey during the day. You know, it's evolved a bunch of different traits and behaviors for it to exploit that time of day as best as possible to its benefit. Now, if it's being forced to use a different time of the day, it's no longer going to get as many benefits from those foods or find those foods or even find mates to pass on their genes as well as they would have if they weren't under high levels of human disturbance. And so you can see how this would then really impact not only individual animal. It would impact the populations and impact communities of wildlife with all sorts of attendant consequences on ecosystems and our environment.

DAVIS: Is it fair to say that humans and animals are finding it harder to coexist?

CARTER: Not necessarily. I think that, in some ways, you can think of this, actually, as a way for animals to coexist with us. You know, many of the most pronounced effects are animals that we think of as often associated with people, like coyotes or foxes - you know, species that tend to do really well where people live because they've become really active at night. And so they can avoid negative interactions like collisions with vehicles or just having an interaction with someone's pet or their livestock if they can just be active at night. So I think, in some ways, it's a mechanism for coexistence. It may not be an ideal situation for wildlife conservation or management, but I think it's a way that they can be flexible and perhaps be able to survive and thrive in increasingly human-modified and dominated areas.

DAVIS: Neil Carter is an assistant professor at Boise State University. Thank you so much for your time.

CARTER: Thank you.

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