There were 3 whisperers, the one Michonne killed, the one Daryl shot in the leg, and Lydia.

I think what we saw was Daryl realizing the whisperers can't "break rank", so to speak. They are surrounded by walkers and the only way to stay safe is to not let the walkers "know" they are people. Like Sam in Alexandria, it was his whimpering that let the walkers notice him. Daryl knew that if he shot them in the head, they would drop and die, regardless if they were walkers or whisperers. So shooting them in the leg was the easy way to tell and making them scream out in pain would attract the walkers to them. In a larger group it would work even better. Imagine a large group of mixed walkers and whisperers. Fire some arrows into the crowd and any whisperer who gets hit will almost immediately give themselves away, and the will instantly be hounded by the walkers who were just protecting them.

I think in the case of the whisperer, he knew he couldn't break rank or he would be in a situation where he has Daryl in front of him and walkers all around him. He would be trapped. So best to keep up the front and just hope Daryl misses or hits another walker, giving him a chance to escape. It was a covered bridge, he had nowhere else to go.

 

I think Earl and Henry need to start working on a few thousand caltrops, to throw in the path of herds from now on.



Problem this, you have to remember they are there later. ;/

 

The Whisperer couldn't react to Daryl's aiming at him as a human would or he risked being swarmed. He probably had no idea what to do in that moment. And then...too late.

Daryl was brilliant to shoot him in the leg!

 

"The living kind or original recipe" had me rofl and to your point about the bridge you can actually see some indecision by the Whisperers in the back (Lydia and the other guy) and they were gonna walk away but Michonne was there waiting for them so they had to fight.

(Ugh recorded and tried to post but file was too large)