Feng Yi didn't stay in that corner all the time. After the group of sparrows flew away, he wandered around the small park, observing the flock from different positions.
Seeing a small group of sparrows resting elsewhere, Feng Yi conducted the same experiment and watched them fly away in panic again.
It wasn't until the sun set in the west and the fading light was overshadowed by the street lamps that the birds also descended onto the branches, no longer active.
At the two spots where Feng Yi had released "chemical signals," the sparrows didn't return for the rest of the day. Even if sparrows landed on the trees there, they left quickly, as if something extremely dangerous lurked.
Clearly, the sparrows' olfactory receptors had detected that chemical substance.
To put it another way, Feng Yi had a brief, not-so-friendly exchange of information with the sparrows.
If it were a communication between predator and prey, it would probably go like this:
Us: "I'm going to eat you!"
