Bats in Winter: The Survival Trick Your Students Will Never Forget

Winter is a shutdown season for insects—and that’s a problem if your whole life runs on flying and eating bugs. So bats do something that feels like science fiction the first time students really “get” it:

They don’t just sleep… they hit the metabolic brakes.

This is the bat survival trick your students will remember long after the unit ends: torpor (and, for many species, full-on hibernation).

First, the winter problem (in one sentence)

When cold weather wipes out flying insects, bats either hibernate in a protected place or migrate to where food still exists—some species even do a mix of both.

The survival trick: Torpor (a.k.a. “energy-saving mode”)

Torpor is a controlled, temporary drop in body temperature and metabolism. Think of it like switching from “high-performance flight engine” to “low-power standby.”

During torpor/hibernation, a bat’s:

heart rate can drop dramatically,
breathing slows,
body temperature falls closer to the surrounding air.

That’s how a small mammal makes a limited fuel tank (stored fat) last through a long winter.

Two winter strategies: Hibernate or migrate

1) Hibernate: ride out the insect-free months

Many temperate bats head to stable winter shelters—often caves, mines, or other protected structures—where temperatures and humidity help them conserve water and energy.

2) Migrate: follow the food

Other species travel to warmer regions where insects remain available (tree-roosting species are especially known for seasonal movement).

Either way, winter becomes a budget season: energy in vs. energy out.

The heart-rate math moment (the “whoa” part)

This is where students’ brains light up—because the numbers make torpor feel real.

A bat at rest can have a heart rate in the hundreds of beats per minute, and during flight it can reach around 1,000 beats per minute. In torpor/hibernation, it can drop to tens of beats per minute.

Try this quick math with the class (no calculators needed if you keep it round):

Example comparison (simple, dramatic)

Active: 600 beats/min
Torpor: 30 beats/min

Now scale it:

Active per hour: 600 × 60 = 36,000 beats
Torpor per hour: 30 × 60 = 1,800 beats

That’s 20× fewer beats—and a giant clue about energy use.

Teacher move: Ask students, “If your heart is the ‘gas pedal’ for your body… what happens when you lift your foot off it for months?”

The “energy budget” truth: Waking up is expensive

Here’s the part that connects physiology to survival strategy:

Arousal (warming up from torpor to normal body temperature) costs a lot of energy. In fact, researchers studying white-nose syndrome have pointed out that each arousal can burn energy that could have fueled weeks of torpor—a big reason winter disturbances can be a serious risk.

Add one more winter pressure: water balance. Dry conditions can increase evaporative water loss, which may push bats to arouse more often to drink—again raising energy costs.

Bottom line for students:

Winter survival isn’t just “sleeping.”
It’s managing a fuel tank—and every warm-up is a withdrawal.

Classroom Connection: “Build a Bat Energy Budget”

You can run this as a 10–15 minute discussion or a full activity.

Step 1: Give every bat a “fat tank”

Start each group with 100 energy points.

Step 2: Winter expenses (students choose)

One day in torpor: –1 point
One arousal event: –15 points
Disturbance (noise/light/visitor): triggers +1 arousal
Dry air: +1 arousal every 7 “days”
(These are classroom-friendly numbers—not literal physiology—but they model the real idea: arousals are costly.)

Step 3: Ask the big questions

What happens if arousals happen more often?
Which strategy lasts longer: “mostly torpor” or “frequent wake-ups”?
How could winter habitat (humidity, temperature stability) change the outcome?

Tie it back to real research: bats affected by white-nose syndrome have been documented arousing more frequently, which is linked to survival outcomes.

A quick stewardship note (worth saying out loud)

If you find bats in winter roosts, the best help is usually distance—because waking a hibernating bat can cost it critical energy.

(For classrooms: observe from afar, learn from posters/models/videos, and leave real winter roosts undisturbed.)

The takeaway your students will repeat

Bats survive winter by turning their bodies into a battery-saving device.
And once students understand the heart-rate math + energy budget, winter ecology stops being abstract.

It becomes a story of strategy: