Birds and the sound of people interacting with nature.

"Have I mentioned how much I hate nature? Because I do. With a passion!"
THWACK
"And stop hitting me!"

So that's one group (with Clarkson) going straight along the paths that Tyler's left in the soggy parts hoping to get lucky and two around the edges looking for points where Tyler might have left, one in each direction of circulation.

The fourth team ia being quiet or they're only going where the other three have passed for now.