Mass Gatherings
What it looks like when a cave releases a river of bats
At major roosts, bats can pour into the evening sky in a stream that seems to keep going long after sunset.
BatsMajor cave and bridge roosts worldwideEvening emergence
Video: Bat Conservation International. Embedded from the original YouTube source.
How big?Large roosts can contain extraordinary numbers of bats.
Why does it happen?Many bats leave communal daytime roosts around dusk to forage.
A major bat emergence creates the impression that the landscape itself is producing animals.
The phenomenon is simply a huge colony leaving its roost to feed, but scale transforms ordinary behavior into a spectacle.
What to know
- Emergence is normal nightly behavior at active roosts.
- Large colonies can create visually continuous streams.
- Responsible viewing means avoiding disturbance at roost entrances.
Good questions
What people usually want to know
Why do thousands of bats leave caves at sunset?
They are leaving daytime roosts to forage during their active nighttime period.