A show-stopping viral video illustrates how nature can turn on us — and on itself – in a nanosecond. We must be ready.

There’s a name for this phenomenon—MURMURATION. It’s simply a massive moving flock of starlings. Technically it’s a collective noun – much like a gaggle of geese or a school of fish.

The stunning video —  posted by filmmakers Sophie Windsor Clive and Liberty Smith – emerged from an evening canoe trip which had no expectations.  But the duo ended up capturing one of nature’s most extraordinary sights: thousands of birds twisting and diving in shape-shifting masses – choreographing a coordinated ballet over the longest River in Ireland – the Shannon.

“We were standing down on the shore and it was like the birds literally saw us on their island, chatted about it and gathered above our heads. It was such a rush and we were utterly overwhelmed,” said Sophie.

According to TIME’s London bureau, “No one knows why they do it. Yet each fall, thousands of starlings dance in the twilight above Gretna, Scotland,  having migrated in the millions from Russia and Scandinavia to escape winter’s bite.”  Scientists aren’t sure how they do it, either. “Even complex algorithmic models haven’t yet explained the starlings’ acrobatics, which rely on the tiny bird’s quicksilver reaction time of under 100 milliseconds to avoid aerial collisions—and predators.”

The lesson?

Sometimes nature chooses us to share her secrets or witness her show of force. We never really know exactly where or when she might strike.  But wouldn’t it be cool if we could always be ready — for that life-altering moment — when she taps us on the shoulder and says, “Watch this.”