Restoring Cut Rainforests Might Not Work Well If There’s Light Pollution Nearby

Fruit-eating bats can’t do their job distributing seeds around the new jungle patch if they’re blinded by lights

Photo: Niklas Agevik

Restoring a previously felled rainforest to its former glory of biodiversity requires more than just planting a few trees and hoping for the best. It can take many, many years for that forest to regrow, and success depends on a number of factors, including, it turns out, light pollution.

If too many bright, manmade lights are present during the night—from boats going by or from people and cars passing on roads or trails—the glare can scare away fruit-eating nocturnal bats. Here's LiveScience on why this is such a problem for recovering rainforests: 

Deforested ecosystems rely on seed-dispersers — fruit-eating animals such as birds and bats — to help re-introduce seeds into empty plots. Frugivorous (or fruit-eating) bats are among the most important seed dispersers in tropical rainforests because they defecate while flying, emitting large quantities of seed-rich feces known as "seed rain" across wide areas. Birds, on the other hand, don't defecate while flying but instead release their droppings from isolated perches.

In a recent study, researchers conducted both field and lab experiments on Sowell short-tailed bats, a common species in Central American jungles, and showed that the bats prefer feeding in dark conditions, rather than those lit by artificial light sources. The team found that, in dark areas containing fruit, bats were twice as likely to enter and to eat those fruits than they were in artificially lit areas, LiveScience reports. The researchers think that avoiding the light might be a defensive mechanism for steering clear of predators—and that, simply, the light probably bothers the bats' eyes.

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