I have two ISA Brown pullets that are about 3 weeks from laying, and I am currently keeping them in a pretty small coop all day. I am planning on allowing them to 'free range' around my backyard after they start laying and their wings are clipped. Is there any way that I can get my chickens back into their coop other than picking them up? They're not fans of being picked up and I can see them escaping through under the fence and running into the vineyard. Could there be a certain treat that they only get when they're back in the coop? How would I go about associating the treat with coming back? I know that's a lot of questions but any advice would be fine

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Food usually works and after that habit.
If your hens have been living just in their coop for a while they should associate this as home.
Buy a few tins of fish, haddock is often cheap and tinned. Drain any oil/water/brine from the tin.
Find a plastic containor, red is a good colour if you can find one but what matters most is you only use this containor to put the fish or other treat food in.
You need to be very strict about this.
For two or three nights feed them a very small amount of the fish/treat food from the containor. Make sure that your hens can see you taking the food from the containor when you feed them.
Feed them from this containor just before they show signs of goiing to roost whille they are still in the coop.
Do this for two or three days.
When you first let them out, do it an hour or so before dusk/roost time. You need to stay with them while you do this.
When you want them to go back into the coop; they will probably head towads the coop at dusk anyway, show them the containor and when they arrive at the coop herd them in and give them some of the treat food.
Anothher more secure method is to make a temporary fence outside the coop and let them roam in this area initially; like a large run. As they get used to going back into the coop you can remove the fence.
Ime, most chicken will return to their coop at dusk anyway. The danger is that when free ranging, especially if they are new to it that they may get stuck somewhere.