With cities worldwide transitioning to the use of energy efficient LED lightbulbs in streetlights, concerns have been raised about the ecological damage they may cause.
Some birds, for example, have adapted to only sing mating calls at night based on the quality of light resonating from a full moon. Therefore, changes in said quality of light can affect bird behaviors.
To learn more, researcher Elizabeth Rowse of the University of Bristol examined how different types of lightbulbs - newer LED versus older, low-pressure sodium (LPS) - affect the behavior of suburban bat populations in the U.K.
Researchers studied bat calls and feeding behaviors both before and after streetlight replacements with LED bulbs. However, unlike birds, their findings revealed that bats are largely unaffected by the switch.
Bats are generally attracted to streetlights, in part due to the high abundance of insects attracted to narrow range UV lights. Previous studies in rural areas of New Zealand found that a switch to LED lights can actually increase insect attraction to artificial lights by as much as 48 percent when compared to high-pressure sodium (HPS) bulbs.
On the other hand, a study conducted in the city of Dusseldorf, Germany, saw the opposite effect: increased attraction to HPS over LED lighting.
While the jury is still out on which bulbs are best, designing more ecologically sustainable cities has become a major topic of conversation in recent years - and understanding how a shift in light quantity and quality will affect current plant and animal populations is an essential piece of the puzzle.
Some propose designing lighting solutions that more closely mimic "natural" non-urban environments, but this is near impossible for cities, where low to no light puts human safety and function at risk.
Therefore, researchers suggest taking a different approach and asking: How do we design lighting solutions that reduce rapid changes from the status of the past several decades? The idea is that this will cause less ecologic shock, thereby giving birds the light they need to sign their mating calls. At the very least, researchers hope to encourage more ecological stability over time.
Their study was recently published in the journal PLOS ONE.
