Why Don't I See Bats Anymore? The Disease Emptying America's Skies

Evening walks used to come with a bonus. Just after sunset, before the light fully gave out, you could count on seeing them — quick, angular shapes cutting across the sky in patterns that never quite made sense until you understood what they were doing. They weren't following anything visible. They were reading the air.

I became interested in bats not because of Batman, but because of the way they navigate. They rely on echolocation far more than on sight — building a picture of the world through sound rather than light. That's a fundamentally different way of being in a space, and I find it genuinely fascinating. Of the more than 6,400 known mammal species on Earth, somewhere between 1,400 and 1,500 are bats. That's roughly one-fifth of all mammals. You'd expect an animal that successful to be everywhere. And yet the evening sky keeps getting emptier.

Bats are disappearing from American skies — not gradually, but in some areas catastrophically. White-nose syndrome has killed more than 90% of certain eastern bat species since 2006, while urban pressures compound the losses. This article traces what's happening, why recovery is so difficult, and what the science says about the animal most Americans have learned to fear.

In this article:
• The Winter the Caves Went Quiet
• A Fungus That Catches Bats Asleep
• Cities Make It Worse — But Not Equally
• The Animal We Fear Is the One We're Failing
• What 53 Percent Means
• Frequently asked questions

The Winter the Caves Went Quiet

Field researchers walking through those New York caves in the winter of 2006 found a scene that has stuck with wildlife biologists ever since.

White-nose syndrome (WNS) is a disease caused by the fungus Pseudogymnoascus destructans, which infects the skin of hibernating bats. The National Park Service traces the disease's name to exactly what researchers first documented on infected animals.

The fungus thrives in the cold, humid conditions of caves and abandoned mines — precisely where bats go to survive winter.

Researchers document white-nose syndrome in hibernating cave bats. The white fungal growth on muzzles and wings gave the disease its name.

The discovery near Albany came from wildlife managers and researchers who noted unusual mortality among hibernating colonies — bodies on cave floors, live bats clinging to walls with the characteristic white dusting on their faces. It was not immediately clear what they were looking at.

What it turned out to be was the start of one of the most severe wildlife disease events documented in North American bats.

White-nose syndrome has spread to most U.S. states and Canadian provinces. At some of the earliest affected hibernation sites, bat populations dropped between 80% and 97%, according to USGS.

Numbers like that don't describe a species having a hard decade. They describe a collapse that was already well underway before most people even knew the disease had a name.

A Fungus That Catches Bats Asleep

This disease is cruelest in its timing: it attacks during the one period when bats have no defenses to spare.

During hibernation, a bat's metabolism slows dramatically. Its body temperature drops close to the ambient cave temperature, and its immune response dials back with it.

Pseudogymnoascus destructans is built for exactly that opening. The fungus colonizes the skin while the bat's defenses are down, and the NPS notes what happens next: it causes bats to arouse from hibernation more often than they should, burning through fat reserves they need to survive until spring.

It isn't a fast kill. It bleeds away the exact reserves winter demands, timed to the one season a bat can least afford it.

The numbers that followed aren't abstract. By 2014, the USDA reported that the disease had killed more than six million bats in roughly six years, spreading to 22 states and five Canadian provinces.

The 2021 USGS news release sharpened that picture species by species: the little brown bat, the northern long-eared bat, and the tri-colored bat — all common in eastern North America — had each declined by more than 90% in affected areas.

Many bat species live 5 to 15 years or longer and typically raise just one pup per year. A 90% population loss in a few seasons is not something they can breed their way back from quickly.

USGS has said as much directly: recovery from catastrophic declines takes decades even under ideal conditions. Conditions have not been ideal — the fungus keeps expanding its range, and an animal that raises one pup a year was never built to outrun something moving that fast.

Cities Make It Worse — But Not Equally

Not all bats vanish from cities the same way — and that distinction matters more than most coverage suggests.

A 2017 review published in the Journal of Urban Ecology highlighted factors that can limit bat abundance and diversity in temperate North American cities — noise, road traffic, artificial light, roost availability, and prey distribution — with effects that vary by species.

Some species adapt to that mix and others collapse under it, depending on how closely their ecology matches what an urban environment can offer.

Artificial light at night disrupts bat foraging routes and concentrates insects in ways that benefit some species while pushing others out.

Some bats use bridges, building gaps, and urban tree corridors and manage to persist. Others depend on old-growth roost sites, continuous forest, and the specific insect communities those habitats support — and those bats fare far worse.

A 2021 study of Mid-Atlantic bat communities adds another layer to that unevenness: after white-nose syndrome moved through the region, it didn't just reduce population numbers but changed which species were present at all. The composition of local bat communities shifted.

A simple headcount decline doesn't capture that kind of loss: it means the ecological roles those missing species played — particularly in insect control — went with them.

You can read more about how ecosystems respond to these shifts in why Earth's vegetation patterns are changing.

Artificial light at night can disrupt bat foraging and flight paths, and lighting management is increasingly treated as a conservation issue in its own right.

It's the kind of pressure that rarely makes headlines, but it points to how many of the stresses on urban bats are things humans generate without intending to.

The Animal We Fear Is the One We're Failing

Bat conservation runs on a central irony: the animal most associated in American popular culture with disease and danger is, by the weight of the evidence, far more threatened by humans than threatening to them.

The US Fish & Wildlife Service has noted that bats are "needlessly killed" because of fear and misunderstanding — even as habitat loss, disease spread, and artificial light, all products of human activity, pose the actual documented threats to bat populations.

The NPS introduced cave closures, visitor restrictions, and decontamination protocols precisely because human movement through bat habitat was accelerating the spread of Pseudogymnoascus destructans.

The ones whose recreational access got restricted were the humans.

Cave closures became a common precaution once researchers recognized that humans can carry the WNS fungus between hibernation sites.

Post-COVID, that irony deepened. A 2022 study tracking bat perception in northern Uganda found that negative attitudes intensified after the pandemic began — and warned that the reaction can fuel persecution of bats and undercut conservation, arriving at precisely the moment bat populations most needed protection.

Perception and evidence don't just diverge in one region. A 2021 review by Wilkinson and colleagues examined common misconceptions about bats and viruses and concluded that claims about bats as direct causes of human disease are frequently overstated or misrepresented in public discourse.

Neither "bats are dangerous" nor "bats are wrongly blamed" captures what the science actually shows. A 2017 study published in Nature, reported by Science, found statistical support for the idea that bats may carry more zoonotic viruses than other mammal groups.

And a 2014 review by O'Shea and colleagues pointed out that confidently linking specific viruses to bats as their primary reservoir remains difficult for many species.

Honestly, the relationship between bats and zoonotic disease is real, unresolved, and almost certainly not well served by the fear response it has generated — which discourages the conservation work that would actually reduce dangerous human-bat contact by keeping ecosystems intact.

What 53 Percent Means

In 2024, USGS released a status report for North American bats. The number that stands out: 53%.

53% of North American bat species, the report found, face a medium or higher level of extinction risk within the next 15 years. More than half. The NPS has separately noted that in some colonies, declines have reached 99%.

North American bats consume enormous quantities of insects — including agricultural pests. The economic value of that service has been estimated in the billions of dollars annually. A continent with half its bat species in serious decline is not an abstraction.

The USDA's public guidance, published as early as 2014, already framed bat conservation as something broader than a wildlife management problem. It asked the public to participate through volunteer monitoring, installing bat houses, and — critically — staying out of caves during hibernation season.

That last ask signals how interconnected the problem is: the disease spreads through caves, the caves are accessible to people, and people have to voluntarily reduce that access for the conservation to work.

USGS has continued tracking white-nose syndrome spread through 2025, with monitoring tools still active across North America.

The geographic range of the fungus keeps growing. The species in its path include populations that have not yet been exposed — and have no acquired resistance.

The boundary between forest and city is where bat populations face the combined pressure of habitat fragmentation, artificial light, and disease spread.

There's something worth sitting with in the structure of this problem.

A slow-breeding animal that hibernates where humans can reach it, that depends on people staying away during the very months it's most vulnerable, and that lives under a cloud of public fear the science doesn't fully support. Every part of this is connected, and none of it resolves quickly.

Some of that connection is written into the biology itself. Bats are colonial animals — they cluster together, which makes them effective hosts for pathogens.

They fly, giving any pathogen access to a mobile dispersal network. Some species share food with hungry colony members.

Those traits, viewed from a virologist's perspective, do make bats worth studying carefully. But viewed from an ecologist's perspective, those same traits are what make a colony of bats above a wetland one of the most efficient insect-control systems in nature.

Maybe the animal we've spent decades treating as a threat is the one quietly absorbing the consequences of how we build our cities and clear our forests.

That's not a comfortable thought. It's probably the right one.

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Frequently asked questions

What is white-nose syndrome and why is it killing so many bats?

White-nose syndrome is a disease caused by the fungus Pseudogymnoascus destructans, which infects the skin of hibernating bats. According to USGS and the NPS, the fungus disrupts hibernation by causing bats to arouse too frequently and burn through their fat reserves before spring. At some affected hibernation sites, bat populations have declined 80% to 97% since the disease was first identified in New York in 2006.

Why are bats disappearing from cities specifically?

Urban bat decline results from multiple overlapping pressures: artificial light at night disrupts foraging and insect distribution, development removes roost sites like old trees and building gaps, and insect populations fall alongside green space. A 2017 review in the Journal of Urban Ecology highlighted noise, road traffic, light, roost availability, and prey distribution as factors that can limit bat abundance and diversity in North American cities, with effects that vary by species.

Do bats actually spread diseases to humans?

The relationship between bats and zoonotic disease is real but frequently overstated. A 2014 review by O'Shea and colleagues noted that confidently identifying bats as the primary reservoir for specific viruses is often difficult. A 2021 review by Wilkinson and colleagues found that many common claims about bats as direct disease sources are scientifically inaccurate or exaggerated. A 2017 study published in Nature, reported by Science, did find statistical evidence that bats may carry more zoonotic viruses per species than other mammals, but that finding does not translate directly to elevated human risk under normal conditions.

How fast can bat populations recover after white-nose syndrome?

Recovery is slow. USGS notes that most North American bat species live 5 to 15 or more years but typically produce only one offspring per year. A population that has declined by 90% faces decades of recovery time even if the disease pressure were removed — and the fungus causing white-nose syndrome has continued to expand its range, so affected species are not simply rebuilding from a single event.

What percentage of North American bat species are at risk?

A 2024 USGS assessment found that 53% of North American bat species face a medium or higher level of extinction risk within the next 15 years. The NPS has separately noted that some individual colonies have experienced declines of up to 99% since white-nose syndrome first appeared.

What can people do to help bats survive?

USDA guidance points to steps like staying out of caves and mines during bat hibernation season to avoid spreading the WNS fungus on clothing and gear, and installing bat houses to provide alternative roost sites. The US Fish & Wildlife Service separately highlights reducing unnecessary lighting near bat habitat as a way to ease pressure on urban bat populations. Volunteer bat monitoring programs also help researchers track population trends across regions.

Why do some bat species do better in cities than others?

Adaptability to cities depends on how closely a species' ecological needs match what urban environments can provide. The Journal of Urban Ecology found that species tolerant of fragmented habitat and lower insect diversity can persist near green corridors, bridges, and building structures. Species that require continuous forest, specific roost trees, or particular insect communities do not adapt well — and a 2021 Mid-Atlantic study found that white-nose syndrome further shifted community composition, removing some of the less adaptable species entirely.

Sources & references

• USGS, "White-Nose Syndrome Threatens the Survival of Hibernating Bats" (2016): usgs.gov
• USGS news release, "White-Nose Syndrome Killed Over 90% of Three North American Bat Species" (2021): usgs.gov
• USGS, "The State of the Bats in North America" (2024): usgs.gov
• USGS FAQ, "What Is White-Nose Syndrome?": usgs.gov
• National Park Service, "What Is White-nose Syndrome?": nps.gov
• National Park Service, "White-nose Syndrome — Bats" (2024): nps.gov
• National Park Service, "Bats Are in Danger. Here's How and Why We're Helping Them.": nps.gov
• US Fish & Wildlife Service, "Bats Are One of the Most Important Misunderstood Animals" (2021): fws.gov
• USDA, "Research, Public Can Help Bats Survive White-Nose Syndrome" (2014): usda.gov
• Ejotre et al., "Negative Perception of Bats, Exacerbated by the SARS-CoV-2 Pandemic, May Hinder Bat Conservation in Northern Uganda," Sustainability (2022): PMC
• Wilkinson et al., "Misconceptions and Misinformation About Bats and Viruses" (2021): PMC
• O'Shea et al., "Bats and Zoonotic Viruses: Can We Confidently Link Bats With Emerging Viruses?" (2014): PMC
• Science, "Bats Really Do Harbor More Dangerous Viruses Than Other Species" (2017), reporting on a study published in Nature: science.org
• Moretto & Francis, "What Factors Limit Bat Abundance and Diversity in Temperate, North American Urban Environments?" Journal of Urban Ecology (2017): academic.oup.com
• "White-Nose Syndrome-Related Changes to Mid-Atlantic Bat Communities" (2021): PMC

This article is for educational and informational purposes only. Sources are linked where available. Readers are encouraged to consult primary sources for further research.