White-nose syndrome is the disease that has wiped out millions of hibernating bats across North America. You won’t catch it, but it changes the rules around the bats in your attic.
It’s caused by a cold-loving fungus, called Pd for short, that grows on bats while they hibernate. Here’s what it is, why it matters, and what it means for you as a homeowner.
What white-nose syndrome is
White-nose syndrome is a fungal disease. The fungus that causes it thrives in the cold, damp conditions of the caves and mines where bats hibernate, and it grows on their exposed skin, which is where the name comes from: affected bats show a white fuzz on their muzzles, wings, and ears.
The disease was first documented in New York in 2006 and is believed to have arrived from Europe, where native bats have built up some resistance. North American bats had none, and the disease tore through them.
How it kills bats
The fungus doesn’t poison the bat. It kills by disrupting hibernation:
- It damages the wings and skin.
- Infected bats wake from hibernation far more often than they should.
- Every time they wake, they burn the fat reserves they need to survive the winter.
- Dehydration and wing damage finish the job.
At badly hit hibernation sites, the death rate can approach total wipeout. Some species have lost the vast majority of their population since the disease showed up.
Which bats it hits hardest
Not every species suffers equally. The worst losses have been in:
- Little brown bats, once one of the most common bats around, now in steep decline.
- Tricolored bats, hit hard enough that they’re being considered for endangered listing.
- Northern long-eared bats, federally listed and devastated in the east.
- Indiana bats, already endangered, with the disease piling on.
- Big brown bats, which still get the fungus but seem to tolerate it better.
What this means for homeowners
White-nose syndrome mostly affects cave-hibernating bats, but it touches your attic situation in a few ways:
- Sick bats act strange. A bat active in winter or in daylight may be sick, and any bat behaving oddly should be treated as a potential rabies risk.
- Protected species. Several affected species are federally protected, which can restrict when and how you exclude a colony.
- Reporting. Some states ask homeowners to report bat colonies in buildings in affected regions. Check with your state wildlife agency.
- Conservation. Putting up a bat house gives displaced bats an alternative roost and helps a struggling population.
Finding a sick bat
If you find a bat in winter, or one that looks sick, has visible fungus, or can’t fly:
- Don’t touch it with bare hands. Use thick gloves or a tool.
- If it’s inside your living space, contain it in a box with air holes.
- Contact your state wildlife agency or a licensed wildlife rehabilitator.
- If there’s any chance of a bite, scratch, or saliva contact, call your health department about rabies treatment.
Frequently Asked Questions
No. The fungus only grows at cold temperatures, colder than a mammal’s body. It can’t infect you, your pets, or your livestock.
No. Proper exclusion is still legal and recommended. Just check your state’s rules first, especially if endangered bats are in your area.
Mostly not. It spreads bat-to-bat in hibernation sites like caves and mines. Attic colonies usually don’t hibernate there, so they aren’t the main route of spread.
Put up a bat house, support bat research groups, avoid disturbing hibernation sites, and follow decontamination rules if you go caving. Cavers are asked to clean their gear so they don’t carry the fungus between sites.
Not yet for wild populations. Research is ongoing, but right now the best conservation tools are habitat protection and stopping the fungus from spreading.
