Twenty years after white-nose syndrome first appeared in New York, the state’s bats, including New York bats, are heading into another winter with a mixed outlook: some encouraging signs for little brown bats, but no broad recovery across the species hit hardest.

The New York State Department of Environmental Conservation issued that reminder in an Oct. 25 Bat Week notice. Its immediate request is straightforward: avoid disturbing bats in caves and mines during fall and winter.

The notice is a seasonal conservation warning, not an announcement that scientists have just discovered a cure. Understanding the difference helps explain why protecting winter shelter still matters.

A disease with deep New York roots

White-nose syndrome was first documented in 2006 in a cave near Albany, according to the U.S. Fish and Wildlife Service. It is caused by a fungus called Pseudogymnoascus destructans, which can grow on hibernating bats.

DEC says the disease has killed more than 90 percent of bats at hibernation sites in the state. That figure describes losses at those sites. It should not be read as a claim that every New York bat species has lost the same share of its population.

Hibernation is a way to survive months when food is scarce. Bats lower their activity and rely on energy stored before winter. Waking repeatedly uses up that limited supply. Disease can trigger extra waking, and human disturbance can add another burden.

The problem is not that a bat cannot wake at all. It is that repeated warming and activity can exhaust its reserves before insects become available again in spring.

Why a hopeful sign is not the same as recovery

DEC reports evidence of stabilization and recovery among little brown bats in recent years. It has not seen similar stabilization in other severely affected species.

The Fish and Wildlife Service’s little brown bat profile adds useful context. This once-abundant animal has suffered severe declines in eastern North America. The federal agency also identifies deaths at wind-energy facilities as another threat.

A population that stops falling may still be far below its former size. And better results for one species do not establish that another species, with different habits and vulnerabilities, is doing equally well.

Rebuilding numbers can also take time. Female little brown bats typically give birth to a single pup in a year, according to the federal profile. These are long-lived mammals, not animals that replace huge losses with large litters each season.

Small animals with an important job

New York has nine bat species, all of them insect-eaters. Six spend winter hibernating in caves or mines, while three tree-bat species migrate to warmer places, DEC says.

Little brown bats hunt around streams, lakes and wooded areas near water. Their varied diet includes moths, midges, caddisflies and small beetles, the Fish and Wildlife Service reports.

That makes bat conservation relevant to farms, gardens and the wider food web, not just to people who enjoy watching wildlife at dusk. It does not mean bats eliminate every pest or replace all other pest-control measures.

Their needs also change with the season. A little brown bat may use a building, tree cavity or bat house in summer and a cave or mine in winter. Protecting one type of shelter does not remove the need for the other.

Researchers are testing several approaches

The federal government’s overview of white-nose research describes work on vaccines, helpful bacteria, ultraviolet light and changes to conditions inside winter shelters. These are research and management projects, not treatments for the public to try.

One effort described by the agency tests ultraviolet light in sites in Michigan, New York and New Jersey. Researchers treat surfaces while bats are away, then measure fungal levels later. The agency reported promising early reductions but cautioned that the results were still preliminary.

Another line of research examines whether cooler parts of mines can slow fungal growth. The same overview warns against simply cooling every cave: conditions that become too cold can also harm bats or drive them away.

These examples show why there is no single easy fix. A method must work against the fungus without damaging bats, other cave life or the habitat they depend on. Findings from earlier trials should not be mistaken for a new statewide treatment rollout.

What New Yorkers can do this winter

DEC asks visitors to obey cave and mine closures and to leave quickly and quietly if they encounter hibernating bats. Its current notice warns that entering a listed bat hibernation site from Oct. 1 through April 30 may lead to prosecution.

For Mohawk Valley residents, the useful takeaway is not to seek out a colony for a closer look. It is to leave winter shelters undisturbed and use official wildlife guidance when a bat problem arises at home.

Bat Week runs Oct. 24 through 31. The need for quiet shelter lasts much longer. After two decades of disease, giving bats an undisturbed winter remains one practical way to support the recovery that scientists are still working to understand.

Reporting note: The current news hook is DEC’s Oct. 25, 2026 advisory. Disease history, life-cycle information and research examples are background, not newly announced findings.