Red light has no effect on bat activity: Less disruption by changing artificial color

Date: June 2, 2017

Source: Netherlands Institute of Ecology (NIOO-KNAW)

 

Artificial light at night can have a disruptive effect on bats, but not if the light is red. Switching to red light may therefore limit or prevent habitat loss for rare, light-shy bat species. The latest issue of Proceedings of the Royal Society B publishes results from five years of pioneering research led by the Netherlands Institute of Ecology (NIOO-KNAW).

It's the first time researchers have succeeded in measuring the effects of light with different spectra on the activity of slow-flying, light-shy bats in their foraging habitat. "We've found these bats to be equally active in red light and darkness," says principal researcher Kamiel Spoelstra. "White and green light, on the other hand, substantially reduce the bats' level of activity."

The effect of red light on more common bat species such as the pipistrelle is reduced as well. Unlike a strong increase in activity of this species in white and green light, the activity in red light is comparable to darkness. This is caused by the strong attraction of insects to white and green (and not red) light. Pipistrelles opportunistically feed on these accumulated insects.

Real-life conditions

"The lack of effect of red light on both the rarer, light-shy species and the more common non-light-shy bats," concludes Spoelstra, "opens up possibilities for limiting the disruption caused by external, artificial lighting in natural areas, in situations where having light is considered desirable."

 

Continued 

Some Turtles See Red Better Than You Do – via Herp Digest

By Joanne Klein 8/19/16, New York Times

You may see red, but you can’t see it like some birds and turtles or the ancient “eagle-lizards” from which they came. According to a study published this month in Proceedings of the Royal Society B, a “red gene” that originated from dinosaurs isn’t just responsible for the red patterns on some birds and some turtles. It also gives them special color vision, allowing them to see differences in shades of red that aren’t detectable to humans.

Most humans can see scarlet and crimson, but the animals with the gene can pick out the shades in between, so two birds that look the same to us appear different to birds with the gene. Known as CYP2J19, the gene comes from the same group that produces enzymes in humans allowing us to break down drugs and toxins in the body, said Nicholas Mundy, an evolutionary geneticist at the University of Cambridge who led the study.

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In birds, he’s found that the red gene converts carotenoids, pigments primarily found in plants, from yellow to a red oil that coats the retina like a lens, augmenting color vision.

Researchers traced the gene’s evolutionary history back some 250,000 years to the archosaur, a dinosaur-ish creature with the skin of an armadillo, head of a bird, snout of a pig, body of a crocodile and belly of a turtle. Dr. Mundy thinks “it’s quite likely that the dinosaurs would have been bright red” with specialized red-oil pigments on their eyes.

The scientists think birds and turtles are the only land animals that still have the red gene. Snakes and scaly lizards split from the archosaur before turtles and lack the red oil on their retinas. Dr. Mundy thinks crocodiles, which spent a lot of time as nocturnal animals, lost the gene because seeing red food wasn’t as important.