Sky's Up Global Astronomy Magazine Volume II (April 2021) | Page 62

altogether . If these recommendations are adopted , the community will still have the lighting it needs , and there will be no loss of amenity . Furthermore they would also solve many of the light pollution problems affecting astronomers . Unfortunately motion operated lighting has never been adopted anywhere , even though some manufacturers have designed motion operated lighting systems . It ’ s a no brainer . So , lighting should only be deployed sparingly , on a must-need basis , where needed , when needed , in the correct amounts and using appropriate smart lighting technology . In addition to compromising astronomy , it is increasingly realized that light-at-night exposure is harmful to human health and the environment . It has been known for a long time that insects are attracted to lights , especially those with a substantial blue light component . Insects will fly around
The night sky is a precious natural resource that belongs to us all , and it should be afforded the same degree of protection as any endangered species . lights and may be killed outright by the heat from the light . Alternatively they can be so exhausted that they will drop to the ground , too tired either to feed or procreate . Street lights can be visible from a great distance by flying insects , so the lights of a city will sweep up insects like a vacuum cleaner over a wide area . With lights remaining switched on all night , 365 nights a year , the effect on insect populations is going to be devastating . Insect populations are going to decline . In the U . K . and elsewhere it was noted that in the mid-20th century , drivers traveling long distances in the summer would find their windscreens splattered with the dead bodies of flying insects that collided with the car . In recent years drivers can travel over similar distances and find their windscreens are as clean at the end of their journeys as they were when they started . Windscreen “ splatometers ” therefore can provide a useful measure of the health of insect populations in a given area . Some insects are so badly affected by lighting that it affects their breeding behaviour , and this has been observed in fireflies that require darkness so they can flash and attract mates . Lighting extends daylight into the hours of darkness , thereby inhibiting their flashing behaviour . In light polluted areas they will simply die off . So , lighting is going to cause insect populations to decline over wide areas , and this is going to have a concomitant effect on higher order consumers such as spiders , amphibians , reptiles , birds and small mammals . Environmental organizations have reported declines in these organisms over the past sixty years or so and these declines correlate negatively with the expansion of street lighting over the same period .
COURTESY
Insects swarm around a flood lamp . It has been known for a long time that insects are attracted to lights , especially those with a substantial blue light component . Insects will fly around lights and may be killed outright by the heat from the light .
Declines in insect populations are usually attributed to pesticides and habitat destruction . This is true , but light pollution was rarely ever considered as part of the equation until relatively recently , even though it was pointed out as early as 1897 2 , and again in 1994 3 . Bats are known to eat about 3,000 insects per night , so if insect populations decline , this could put severe pressure on the local bat population , resulting in bats not being able to find enough to eat . If lighting is killing of the insects , then the bats won ’ t get enough to eat , and they will be unable to build up the fat reserves necessary to keep them alive over the winter hibernation period . Insufficient food lowers their resistance to disease , and opportunistic infections may take advantage . Outbreaks of white nose syndrome , caused by a fungus , Pseudogymnoascus destructans 4 , have been observed in bat populations in the United States where starving bats have been seen foraging over the winter period . Declines in bats can have an effect on insects that are not attracted to lights ; bats eat large numbers of mosquitoes , so if bat populations decline , mosquito populations may increase . It is now known that foraging behaviour in bats declines during bright moonlight , probably due to the increased risk of predation . If so , then it can also be expected to decline in areas that are permanently illuminated at night , leading to a concomitant decline in bat populations . The bats will simply move elsewhere . In the United Kingdom it is illegal to harm bats in any way , so this raises the question as to whether our municipalities are culpable by lighting up our environment to the point where they are denying food to bats and reducing their numbers . Light pollution could also affect the regeneration of tropical rain forests by disrupting the seed dispersal behaviour of fruit bats . In Costa Rica 5 it was found that fruit bats avoided foraging
32