HOW DO BATS AVOID CHAOS?

It’s an age old question, especially since it was thought bats were blind, or they were clumsy flyers that get tangled in people’s hair. But over the years it has become more widely accepted that bats are incredible aerial artists.

Imagine flying through a dense crowd of thousands – all shouting at once – while trying to avoid collisions, hunt for food, and navigate your surroundings. Sound pretty hard doesn’t it? For bats, this is a nightly challege. A new study published in PNAS (Goldshtein et al., 2025) reveals just how extraordinary their sensory and navigational abilities really are.

The Challenge: Echolocation in a Crowd

Echolocating bats rely on sound to “see” their environment. But when thousands of individuals emerge from a cave at once, their calls can overlap, creating severe acoustic interference – a scenario known as the “Cocktail Party Nightmare”. This makes it incredibly difficult to detect nearby bats and avoid mid-air collisions.

By using miniature ultrasonic microphones attached to greater mouse-eared bats (Rhinopoma microphyllum) and a high-resolution tracking system (ATLAS), researchers were able to record what a bat hears from its own perspective during collective flight.

They combined this with a sensorimotor model to simulate how bats adjust their behaviour in real time. The result: the most detailed look yet into how bats cope with intense acoustic interference during mass emergence.

Their key findings included:

1. Bats spread out quickly
   • As the bat exited the cave, they rapdily dispersed, increasing space between individuals.
   • Within just a few hundred metres, inter-bat distance grew from ~14 m to over 60 m.
   • This reduction in density signficiantly lowered acoustic masking and the risk of collision.
2. Masking declines within seconds
   • Despite the chaos at the cave entrance, acoustic masking dropped sharply within 25 seconds of flight.
   • Even under dense conditions, bats managed to detect enough echoes to navigate and avoid obstacles.
3. Collision risk is extremely low
   • Using the sensorimotor model, researchers estimated an average of only 1.2 collisions per bat over the first 1.3 km of flight.
   • Most pf these collisions occurred near the cave entrance; collisions were rare once bats were in open air.
4. No need for “Jamming avoidance”
   • Contrary to popular theories, bats did not adjust their calls to avoid overlap with others (a jamming avoidance response).
   • Instead, they exhibited a “clutter response”: shortening calls, increasing call rate, and slightly adjusting frequency – techniques used when flying near any obstacles, not just other bats.
5. Emerging in waves reduces problems
   • The team simulated higher-density emergences (50 and 115 bats/second), as seen in larger colonies.
   • In all cases, collision risk and echo masking decreased rapidly once bats spread out – demonstrating the effectiveness of this simple strategy.

Why this matters?

This study shows that bats don’t need complex social signalling or sophisticated anti-jamming behaviours to navigate in huge groups. Instead, simple, sensor-drive movement and spacing strategies allow them to maintain group cohesion and avoid crashing – even when acoustic chaos is at its peak!

You can read the study here [Goldshtein, A., et al. (2025). Onboard recordings reveal how bats maneuvre under severe acoustic interference. PNAS, 122(14), e2407810122]

HOW DO FORESTS SHAPE WINTER BAT ACTIVITY?

As bat activity continues to be recorded through the winter months in warmer regions, a key question remains: what keeps bats active in the colder season—and how do forest structure and insect availability play a role?

A new study by Perea et al. (2025) published in Forest Ecology and Management dives deep into how winter bat activity in southeastern U.S. pine forests is shaped by a combination of temperature, forest structure, and insect composition—offering timely insights for forest managers and conservationists alike.

What was studied?

The research teamconducted acoustic and insect surveys across four large working forest landscapes in Florida, Mississippi, North Carolina, and South Carolina from January to March (2021-2022). They investigated how forest stand characteristics, temperature, and insect richness and size influence bat activity, using structural equation modeling (SEM) to explore direct and indirect relationships.

Their key findings included:

1. Temperature is a driving force
   • Warmer nights led to higher bat activity across nearly all species.
   • Temperature also driectly boosted insect richness and abundance, especially among larger insects (important winter prey).
2. Forest structure shapes foraging opportunities
   • Bats showed a strong preference for semi-open stands (e.g. thinned or mid-rotation pine areas).
   • Closed-canopy pre-thinned stands generally had lower bat activity – likely due to limited insect availability and cluttered flight space.
3. Insects matter more in winter
   • While previous summer studies found insect abundance less influential, this winter-focused study found stronger linkes between insect richness and bat activity, particularly for edge and interior-foraging species.
4. Forest management has cascading effects
   • Forest structure influence insect community (e.g. Diptera, Coleoptera, Lepidoptera).
   • These insects shifts then indirectly impacted bats – highlighting cascading ecological relationships between vegetation, prey, and predators.
5. Species-specific responses
   • Open-space foragers (e.g. Brazilian free-tailed bats, hoary bats) responded more directly to temperature and stand openness.
   • Edge/interior foragers (e.g. tricolour bats, evening bats) were more sensitive to insect richness and forest structure.

Why this matters?

This research challenges previous assumptions that winter bat activity is minimal in temperate pine forests. Instead, it demonstrates that even in winter, bats are actively responding to complex habitat and prey dynamics.

You can read the study here [Perea, S. et al. (2025) Disentangling winter relationships: Bat responses to forest stand structure, environmental conditions, and prey composition. Forect Ecology and Management, 578, 122484]

STORM RIDERS: BATS USE WEATHER FRONTS TO POWER SPRING MIGRATION?

We’re used to hearing about birds riding tailwinds during migration — but did you know bats do it too? A groundbreaking study by Hurme et al. (2025), published in Science, reveals that female common noctule bats (Nyctalus noctula) strategically “surf” storm fronts during their long-distance spring migrations across Europe.

This is the first study to directly track full migration journeys of individual bats using tiny, smart GPS and motion-sensing tags. What it reveals is extraordinary.

How did they do it?

To track the bats, researchers used ICARUS TinyFox-Batt IoT tags — cutting-edge tracking devices designed specifically for small, flying animals like bats. These miniature bio-logging tags weighed just 1.2 grams and were equipped with:

• GPS modules: to track the bats’ geographic location during migration
• Accelerometers: to measure VeDBA (Vectorial Dynamic Body Acceleration), a reliable proxy for energy expenditure
• Temperature sensors: to record environmental and tag temperature
• Onboard data processors: to summarise and compress the data on the tag itself
• Wireless transmitters: which used the Sigfox 0G network (a low-power, wide-area network) to send data remotely to researchers

This tech allowed scientists to remotely monitor movement, activity, and energetic costs across entire migration journeys—without needing to recapture the bats.

Their key findings inlcuded:

1. Bats time departures with warm fronts
   • Most bats departed on nights with incoming storm fronts, using the tailwinds and rising air pressure to travel longs distances ore efficiently.
   • Wind support clearly improved migration efficiency – reducing energetic cost.
2. Flexible and adaptive migrants
   • While most bats used storm fronts, other migrated under less-than-ideal conditions.
   • Bats that departed later in the season had higher energy use per kilometer travelled – suggesting a cost to this flexibility.
3. Impressive distances in short bursts
   • Bats covered up to 1,116 km, flying tens to hundred of kilometres per night.
   • Migration was not continuous – bats paused frequently for stopovers, refuelling along the way,
4. Energy use tied to movement type
   • Using acceleration data, researchers showed that migration flights had 2.5 x more energy output than foraging flights, and inactive days involved minimal energy use, confirming strategic rest days.

Why it matters?

This study is a huge leap forward for understanding bat migration, which remains one of the least-known aspects of their ecology.

It also provides a powerful conservation message: Wind turbines, changing storm patterns, and climate shifts could severely affect bat migration if their ability to use favourable winds is disrupted.

Additionally, this study proves the power of biologging technologies in bat research, making long-range tracking of even small bats feasible without recapture.

Read the full study here [Herme, E. et al. (2025) Bats surf storm fronts during spring migration. Science, 387(6729), pp. 97-102].

From storm-surfing noctules to winter-active foragers and chatty migrants, 2025 has already brought some incredible new insights into the secret lives of bats. It’s amazing how much we’re still learning, and how every study brings us closer to understanding these remarkable animals.

We’ll keep sharing highlights from the latest research here—so whether you’re out volunteering, spotting bats in your garden, or just curious about what they’re up to, we hope you’ll stay with us for the journey.

Thanks for reading, and happy bat watching!