Hello, and welcome to BYC.  Any possibility that one or both of the chicks are hiding somewhere ?
		
		
	 
That's what i was thinking.
And bummer on the whole situation. I've been waiting for and dreading and trying to prepare for the day i have to lock up my girls. Sorry they found your flock
If you decide to add to your run, I've found pressure treated 1x4x8's to be very manageable.  2x4's are sort of too heavy for me.  I've been making panels with 1x4s and 2' wide 1/2 inch hardware cloth.  I staple the hardware cloth to 2 boards (cut to 67" in my case),
then i cut 2 1x4s to go the whole width of the panel (joins the 2 sides.)  (Cut the hardware cloth with snips before screwing on the board. I use 1- 5/8" deck screws with fender washers.)
Then flip the panel, staple the hardware cloth, and cut pieces of 1x4 to go between the sides, top and bottom. Sandwich the metal mesh edge, screwing it together with the same screws and washers.
Sandwich the verticals (when you get more wood!)
I'm finding the panels very manageable and because I'm using standard widths, i can modify things in the future without too much to do.
Unlike all my previous mishmash building.
I thought I'd prefer mesh that's wider than 2 feet, but 2 feet was available.