Holland’s newest red-light district is a big boost for bats

Kamiel Spoelstra has 1.5 million recordings of bat sounds. Spoelstra and his team of scientists at the Netherlands Institute of Ecology (NIOO-KNAW) made them, in order to analyze the effect of outdoor artificial light on the nocturnal creatures. Starting in 2011 they mounted microphones and memory cards on trees near specially-tuned LED lightposts they installed at eight different sites in the Netherlands. Spoelstra’s ultrasonic equipment would pick up the high-frequency bat calls that are inaudible to human ears but that sound out at deafening decibels that put Iron Maiden to shame.