Filming the “resurrection moment”, when bats wake up from hibernation, was our goal. Every day, myself, two scientists, three filmmakers, an editing assistant, and a local fixer all fanned out into the forest of northern Hokkaido in search of bats. The scientists took us to their favorite places, then we just split up and searched. Unfortunately, no particular technique or technology facilitated our search. All you had to do was watch for the tiny balls of inanimate fluff on the forest floor, sometimes still half-buried, often mixed with brown leaf litter. All we had to do was look at each patch of snow, examine each little brown drop and always watch where we stepped.

Seven crew members is a lot for a shoot like this, but this number was necessary: ​​capturing this behavior was going to be a challenge. Timing was everything – the bats would only be revealed when the last foot of snow had melted and would therefore be entirely dependent on the weather – never a good starting point for making a natural history film. So, for each bat found, we would only have one chance to film the moment of takeoff. But with a large team, warm, stable weather, and Mr. Nagasaka proving to be a champion bat finder, we had several chances to succeed.

Remarkably, the bats would go from almost dead to ready to take off in just about an hour. If they spend the night outside in the newly exposed slush, they could freeze to death. The process begins with a twitching of the ears, but quickly accelerates to a furious vibration, as the bats warm their flight muscles to operating temperature. When everything is ready, the bats lower their arms with all their strength and launch into the air. Not all of the bats were successful, and some came crashing back to the ground with a very quiet thud. But most, in one way or another, rose vertically into the air and disappeared.