Wednesday, May 11, 2016

Too Much Light!

Outdoor light
Most of it is wasted, aiming to the skies
© Beatriz Moisset

Could it be that we have too many outdoor lights? Night lights have become so abundant that they can be seen from space. Large cities are beacons made of myriads of tiny dots of light. The planet has never seen anything like it before. We know the benefits of good illuminated streets and public areas. Could there be some drawbacks too?

For one thing, we have lost the ability to see the night sky in all its splendor. Most stars have become invisible to city dwellers. Even in the suburbs and some distance from large cities, lights affect our vision of the sky. Astronomers regret this deeply and have some suggestions on how to mitigate the impact of night lights.

Night lights have other effects worth discussing. We all know that moths are attracted to lights. We often see a handful of them flying aimlessly around our porch lights or finally settling on a wall for the rest of the night. They are still there the next morning and remain still for the day since they are not day fliers.

How does this affect moths? Undoubtedly, such behavior may cost some of them their lives by exhaustion and lack of food. Does it matter?

Many moths are pollinators of night flowers. Nature is rich in its approaches to issues. Although most flowers bloom and are pollinated during the day, preferably when the sun is shining, a few take advantage of the darkness of dawn and dusk and even the middle of the night. Thus, they take advantage of certain flower visitors that have developed a similar strategy, namely being active at night.

Thyatira lorata moth
Attracted to night lights and
spending the day where it finally rested
© Beatriz Moisset
This is how a partnership has developed between some flowers and nocturnal moths. Ordinarily, such flowers are white or cream colored and have strong scents, better to attract their pollinators. Moths, in turn, have good night vision and a strong sense of smell.

Getting back to light pollution, if it kills moths, it too may be affecting the pollination of night blooms. We don't know this for sure, but there are strong indications that this is the case. Also some evidence points to night lights affecting the growth of some plants by getting their schedule confused.

We should follow the suggestions provided by several websites on how to minimize light pollution, for instance the Florida AtlanticUniversity website covers a lot of ground. One useful recommendation is "no light should be emitted above the source's horizontal plane."

The Mother Nature Network lists five ways you can reduce light pollution:
  1. Start with the light switch
  2. Check with your power company to see if you're paying for outdoor lighting
  3. Consider replacing outdoor lights with intelligently designed, low-glare fixtures
  4. Place motion sensors on essential outdoor lamps
  5. Replace conventional high-energy bulbs with efficient outdoor CFLs and LED floodlights
However most of these ideas, although excellent provide no significant protection to pollinators and their plants. For this purpose one valuable tip is to abstain from lighting the landscape. There is no real need to illuminate your trees, shrubs and the general area where they grow, so let us give up this kind of lighting, please.

Virginian tiger moth
© Beatriz Moisset

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