There are a number of well-known ways to keep babies healthy — wash your hands often, get them vaccinated, don’t smoke inside, and so on.
But there’s one thing you probably haven’t heard of: protecting bats. Like literal flying bats.
That’s one takeaway from a remarkable new study, published in the journal Science, that links the decline of bats to a rise in newborn deaths in the United States.
By compiling and analyzing a huge amount of government data, environmental economist Eyal Frank, the study’s sole author, discovered that in regions with outbreaks of white nose syndrome, a wildlife disease that kills bats, the rate of infant mortality increased by nearly 8 percent relative to areas without the disease.
There’s a clear reason for this, according to the paper. Most North American bats eat insects, including pests like moths that damage crops. Without bats flying about, farmers spray more insecticides on their fields, the study shows, and exposure to insecticides is known to harm the health of newborns.
“When bats that eat insects go down, farmers compensate by using more insecticides,” Frank, an assistant professor at the University of Chicago Harris School of Public Policy, told Vox. “That has adverse health consequences — full stop. The damages from their absences appear to be substantial.”
Earlier research has found that wolves help limit car accidents by keeping deer off the road. Other research, also led by Frank, links the sudden decline of vultures in India to an increase in human death rates. Vultures eat animal carcasses that, if left to rot, can pollute waterways and feed feral rats and dogs, a source of rabies.
When the link between human and environmental health is overlooked, industries enabled by short-sighted policies can destroy wildlife habitats without a full understanding of what we lose in the process. This is precisely why studies like this are so critical: They reveal, in terms most people can relate to, how the ongoing destruction of biodiversity affects us all.
When bats disappear, farmers spray more
Not everyone finds bats cute — they are! — but these animals are undeniably impressive. They’re the only mammal on earth that can truly fly. Plus, they eat astounding quantities of bugs. A single bat can catch several hundred insects an hour, and thousands in a single night.
This is good for us: Many of the critters that bats consume during their nightly hunt are insects that we don’t like, such as blood-sucking mosquitos and crop-eating moths and beetles. Bats are, essentially, a natural pest control.
So it stands to reason that without bats, farmers have to use more insecticides on their crops; agrochemicals do the job that bats do for free.
There hasn’t been a great way to test that theory, until somewhat recently, when bats across North America began dying en masse. In 2006, a fungal disease called white nose syndrome appeared in New York state and began spreading among bat colonies, killing an average of more than 70 percent of the bats within them. It’s been brutal. WNS invades their skin, producing fluffy white growths around their noses, and wakes them up during hibernation when they should be resting. Infected bats burn off vital energy stores and either freeze or starve to death.
Devastating as it may be, the rapid loss of bats has provided researchers with a rare opportunity to test what happens when these animals disappear from the landscape. In the new study, Frank — who works at the intersection of economics and conservation — analyzed data on pesticide use across US counties with and without WNS, which until recently were mostly in the eastern US. Where there’s WNS, there are presumably far fewer bats.
His results were astonishing: Farms in regions hit by WNS used 31 percent more insecticides on their crops, compared to counties without the disease. That suggests that when bats disappear, farmers compensate by using more chemical bug killers.
At what cost?