There are many well-known ways to keep children healthy — washing your hands often, getting them vaccinated, not smoking indoors, etc.
But there’s one thing you might not have heard of: protecting bats. Literally like flying bats.
That’s one significant takeaway A new studyPublished in Journal science, K The decline of bats has been linked to an increase in infant mortality in the United States.
By compiling and analyzing vast amounts of government data, environmental economists Eyal FrankThe study’s sole author found that in regions where white-nose syndrome, a wildlife disease that affects bats, was particularly hard hit, infant mortality increased by about 8 percent.
According to the paper, there is an obvious reason for this. Most North American bats eat insects, including moths that damage crops. Without bats flying, farmers spray their fields with more pesticides, studies show, and pesticide exposure harms the health of newborns.
“When bats eat insects, farmers compensate by using more pesticides,” said Frank Vox, assistant professor at the University of Chicago Harris School of Public Policy. “It has adverse health consequences – full stop. The damage caused by their absence appears to be significant.”
Frank’s study adds to a growing body of research that supports the idea — which should probably be obvious by now — that healthy ecosystems are critical to human well-being.
Previous research Wolves have been found to help limit car accidents by keeping deer off the road. Other researchFrank also linked the sudden decline of vultures in India to an increase in human mortality. Vultures eat animal carcasses which, if left to rot, can pollute waterways and feed on wild rats and dogs, sources of rabies.
When the link between human and environmental health is ignored, industries enabled by short-sighted policies can destroy wildlife habitats without a full understanding of what we are losing in the process. This is why studies like this are so critical: they show, 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 they are undeniably impressive. They are the only mammals on earth that can actually fly. Also, they eat a surprising amount of bugs. A single bat can catch several hundred insects in an hour and thousands in a single night.
This is good for us: Many of the critters bats eat during their nocturnal hunts are insects we don’t like, like blood-sucking mosquitoes and crop-eating moths and beetles. Bats are, essentially, natural pest control.
So it stands to reason that without bats, farmers have to use more pesticides on their crops; Agrochemicals do the work that bats do for free.
There was no good way to test this theory, until fairly recently, when bats across North America died out en masse. In 2006, a fungal disease called white nose syndrome appeared in New York state and began spreading through bat colonies, killing an average of more than 70 percent of the bats. It has been brutal. WNS invades their skin, produces fluffy white growths around their noses, and wakes them up during hibernation while they are resting. Infected bats burn vital energy stores and either freeze or starve to death.
As devastating as it is, the rapid loss of bats has provided researchers with a rare opportunity to examine 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 in US counties with and without WNS, which until recently were mostly in the eastern US. Where there is WNS, there are probably far fewer bats.
The results were striking: Farms in areas affected by WNS used 31 percent more pesticides on their crops than those in counties without the disease. He suggests that when bats disappear, farmers compensate by using more chemical bug killers.
At what cost?
Terrible consequences of losing a bat
First, there is the cost to farmers. According to Frank’s study, the decline of bats cost the agriculture industry nearly $27 billion between 2006 and 2017, as reflected in reduced income in regions with white-nose syndrome. The cause of this loss is not clear, though it may be that bat-free regions produce lower-quality crops, Frank said.
A Study published in 2022 supported a similar conclusion, linking the spread of WNS to a decrease in the rental price of agricultural land. The idea is that farmers have lower yields or spend more money growing crops — such as buying pesticides — when no bats provide free pest control. (I interviewed Amy Endo, one of the study co-authors, for an episode of the Vox Science show Inexplicable. you can listen here.)
Then there is the serious cost of human life.
It is well known that when farmers spray pesticides on their fields, those chemicals can enter the environment, where they pose a risk. public health. one A recent review Link pesticide exposure in newborns, for example, to lifelong abnormalities and diseases. With this in mind, you might expect that areas without bats, where farmers use more pesticides, have more health problems.
Frank also tested this theory, using government data on infant mortality, due to the prevalence of white-nose syndrome. The results of his analysis were alarming: The rate of internal infant mortality — children who die from causes other than accidents or homicide — increased by about 8 percent in counties after the WNS outbreak. Put another way, when pesticide use increases by 1 percent, infant mortality increases by a quarter of a percent, comparable (though slightly less) to the effect of ambient air pollution.
“I was surprised that the sign [in the data] was very strong,” said Dale Manningenvironmental economist at the University of Tennessee Knoxville, who was not connected to the study. “They’re big, big numbers in terms of financial impacts, but we’re also talking about human lives, right? And so those impacts are pretty significant.
Manning and Endo, Environmental Economist At Ohio State University, who was not involved in the study, said the paper’s findings were correct. (Both Endo and Manning were involved in the 2022 study cited above.)
While research does not definitively prove that bats cause declines The study ruled out other possible factors behind this trend, including pesticide use and increased child mortality. Frank also found that when bat declines were more severe—when more bats died, more caves were infected, or the decline was more severe—infant mortality was higher.
A very good reason to save nature
Such studies form the address More urgent is the ongoing decline of bat populations. In North America, more than half of all bat species are “at risk of severe population decline in the next 15 years,” according to 2023 report Through the North American Bat Conservation Alliance, a coalition of groups including government agencies and Bat Conservation International. This is the trend reflected Globally.
WNS continues to spread westward, invading new territories. Climate change is also harming these animals. Bats Flight-adapted physiology Making them extremely vulnerable to severe droughts and heat waves, as I reported earlier. Plus, wind turbines—an important climate solution—kill thousands of bats every year in North America alone. In general, bats, most of which are migratory species, are killed by collisions with turbine blades, although they Why is not clear These animals are drawn to them.
It’s not all bad news; There are ways to help bat colonies survive. scientists has been tested For example, the vaccine for WNS. And Research shows that slowing down wind turbines at night during certain times of the year reduces collisions.
But these approaches can be expensive—which underscores the value of studying, with greater clarity, the payoffs of investing in conservation, both in dollars and in human lives.
“At the end of the day, scientists and policymakers have to justify allocating resources to things like fixing bridges and fixing schools or fixing bats,” Manning said. “They all have different returns associated with them.”
“And if we don’t try to show what the benefits of ‘fixing’ bats are,” he said, “those benefits will be discounted.”
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