Getting into the backcountry for the darkness? Listen next, to part two of The Wilderness at Night, on the WildeBeat.
*** News from the Wildebeat, the audio journal about getting into the wilderness. This is program number fourteen.
I'm Steve Sergeant. *** STEVE: When we think of spending time in wild places, most of us think of what we're going to do during the day. But half of the time of any given year, the wilderness is dark. And half of that time, when the moon isn't up, the wilderness can be really dark. But how dark can it get? Is it as dark as it always was?
Chad Moore is a physical scientist for the National Park Service. As the program manager for the park service's night sky team, he's been trying to answer those questions within the national parks for the past six years. CHAD MOORE: This team started in 1999, and we were focused on how much light pollution do we experience at various parks, what's the quality of the sky, and we developed a photometer, which is a fancy name for a light meter to measure the sky. I believe that the instrumentation that the Park Service has is basically one of a kind.
STEVE: What's that like? Can you describe a typical session of going out and taking those measurements?
CHAD MOORE: Well, we work during the new moon, so I can only do this work for about ten days a month, and we generally set up in the dark, and the equipment takes two to three hours to collect the data. We choose mountaintops if we can, where we can get an unimpeded view of the horizon so our instrumentation can capture the, what we call the light domes from each of the individual light pollution sources.
STEVE: Is the sky glow getting stronger or are things improving?
CHAD MOORE: Some of the sites we've gone to it's taken us two or three years to collect the data. Sometimes it seems it's gotten brighter just in the time that we're trying to collect the inventory. Plus we know from just population increase and the increase in energy use in outdoor lighting, which has gone up, not down, by the way, that light pollution should be getting worse.
STEVE: With the darkest night skies getting brighter, I wondered about the effects this would have on the delicate balance of life in wilderness areas. Geographers Travis Longcore and Catherine Rich have edited a new book on the "Ecological Consequences of Artificial Night Lighting". This book is a collection of the best and latest scientific papers on the subject.
Doctor Longcore talked to me to summarize the results presented in the book: TRAVIS LONGCORE: What you're doing is you're taking away the darkest part of the night, permanantly, so that period of the new moon will be gone, and the reason that that matters, is it upsets relationships between predator and prey. Certain things that depend on that darkness will no longer be able, or will be less able, to do their natural thing.
So there's a lot of planning for corridors to link up big blocks of habitat for large creatures like cougars, but without looking at that at night and saying "Is that corridor dark? Is the animal going to use this corridor at night?" you may be, sort of, doing all that for naught.
Sea turtles, which nest along oceanic beaches are affected in two ways. Female sea turtles, which can be quite large, will not crawl up onto the beach to lay their eggs where there is artificial light. They will choose their location by avoiding the light. And second, when the sea turtle hatchlings come out, which are tiny, cute little things, they can be disoriented by artificial light. They don't make it to the ocean. They get run over by cars, eaten by predators, or dessicated and killed in the sunlight in the morning.
All of the small mammals that forage at night: kangaroo rats, and the nice things that will come around to your campsite, there's a long set of studies that show that increasing illumination decreases the amount of activity of these small mammals. You'll also find things like snakes — of course they have as predators owls, and there are some snakes that will be most active during the new moon — that darkest part of the night — rather than during the full moon where they're more susceptible to predation. As you have more light pollution in these places, you would then end up with sort of simplified biological communities. So that some of the organisms that specialize in the night, in the dark of night, will just no longer be present.
STEVE: So does a brighter night sky affect the relationship between plants and animals?
TRAVIS LOGNCORE: Yeah. There's a famous saying that not only is nature more complex than we think, but it's more complex than we can think. There's a well-documented pattern in the zoaplankton in lakes, especially things like daphnia, where they will migrate to the surface of a lake during the dark of the night, and there they'll graze on the phytoplankton, the algae, and then when it gets lighter they go back down. And this follows a lunar cycle. During the full moon they don't come up as high. And the reason for this is that they're susceptible to being eaten by fish if it's too bright. Light pollution from cities will affect this migration of zoaplankton in lakes and ponds up and down in the water column, and effectively keep them from coming as far up as they would normally. If those zoaplankton aren't there to eat the algea that's up at the surface, you can then have algae blooms where you get lots of algae and a whole series of other sort of responses of the system to not having this natural monthly cycle of grazing. So, you know, the sorts of interactions and things that would happen, we can't even really predict because there are these intricate relationships between, for example, plants and animals that disperse their seeds. OK, say it's an ant that disperses the seed of a plant, and that ant — and I'll give you an example — there's an ant in Texas that does this — has a nuptial flight, a mating flight that's very tightly correlated with a specific time before dawn. And all the ants, they fly, mate and form new colonies. They've shown that timing of the reproductive flight is disrupted in areas that have light pollution. So down the road, what does that mean? Well, maybe that's bad for the ant, but maybe eventually it's bad for the plant species that depend on that ant to disperse its seeds. So as you sort of tug on the tapestry of interactions of species in the wild, you don't know what exactly what you're going to unravel. STEVE: What evidence is there for direct effects on plant life?
TRAVIS LOGNCORE: This is a really interesting area. We have a lot of studies on plants in the lab but not a lot of studies in the wild. A couple of things that can happen. One, the perception of a photo period can be altered, in other words, how long a day is, because certain plants cue in to do things on day length. A great example might be a deciduous tree losing its leaves in the fall. As the days get shorter, there's a certain trigger there, and the plant will pull their resources in out of the leaves, they turn color, they drop off. Trees that are right next to lights will hold onto their leaves much longer, and that has a cost to the plant, uh, because then it will be exposed to adverse environmental conditions without having prepared for them. Because losing leaves is basically the — the tree's way to prepare for getting cold. Flowering — there's a prison official that had reported that the soybeans in the field surrounding the prison would not flower because they were being exposed to very bright lights from the prison. STEVE: When we get into the wilderness in the next few years, how are these changes going to look to us?
TRAVIS LONGCORE: People, from birdwatchers to, you know, frog catchers, amateur herpetologists to butterfly watchers may actually be the people who notice. But for the general public, the issue of the night sky is the easiest way to communicate the importance of this. Because it's very intuitive to start to realize that hey, if I can't see those stars, then a bird can't see those stars. And that I think really rings a bell with people.
STEVE: One thing I learned in my conversations with both scientists, is that solving light pollution problems is not technically difficult. An organization called the International Dark Sky Association publishes a wealth of information on ways to make lighting safer, more efficient, and less pollution-causing — all at the same time. They point out that so many of the problems of light pollution come from inefficient and ineffective light fixtures.
You can find out more about getting started in wilderness stargazing, which we discussed in part 1, about the book "Ecological Consequences of Artificial Night Lighting" by Travis Longcore and Catherine Rich, and find a number of other related links, on our web site. *** Next time - a winter storm warning. The Wildebeat is produced by Steve Sergeant for Effable Communications. Our official website is WWW dot WILDEBEAT (that's W-I-L-D-E-B-E-A-T) dot NET. Please see our website for ways to ensure future editions of The WildeBeat. Send your comments to webmaster at wildebeat dot net.
This has been The Wildebeat, program number fourteen. Thank you for listening.
