Why do chickens need a coop?

I live in the suburbs, I have 1.7 Acres, and I am planting a healthy forest of different trees and such, I have just split my land up into 3 large sections to practice this paddock shift system, I have listened and read about. I was wondering, I live probably 5 solid miles of suburbs before anything you would call wild, and I don't have racoons, or skunks in my area, so why do I NEED a coop?

I have a horse barn stall I set a side for them to sleep in during the winter months, but during the warmer months, couldn't I just let them find a favorite spot in the trees?

Only if there are no predators in your area. You may be surprised how many raccoons live nearby even though you never see them. They have adapted well to suburbia.

It's very sad to lose chickens to raccoons, evil carnivorous monkeys that they are.

Chickens don't need a coop, but they need a safe place stay the night. They're happy to roost in trees, but thick shrubs or undergrowth will work well, too. If you let them take the natural route, though, you have to be prepared for the natural result-- you will lose some to predators. I'm not cool with that, personally (though I think it's the most permacultural approach), so we have sheds they stay in at night.

I'd be surprised if you don't have raccoons, but you may not. You certainly have some predators in your area, though. If not coyotes, raccoons, possums, skunks, foxes, owls, feral dogs, or feral cats, then at least some pets whose owners let them roam free at night. Nature abhors a vacuum.

If you went coop-free, and tolerated your early losses, you'd end up with a flock that was very smart about choosing its roosting spots.

I live on 10 acres and have most of the predators listed and have suffered some losses even with my electro-net fencing. However I do have 2 white leghorns that prefer to roost in a tree or tall bush over the coop. When I have them in an area of particularly dense brush none of the chickens roosted in the coop, but this was June. Also I had a real problem finding the eggs as they abandoned the nest boxes as well.

Word of warning before you just fence off an area and put the chickens in it. If there is a burrow inside the fence you have just created a buffet for whatever is living in that burrow - don't ask how I know this.

I live in an urban area where the predators are very few and I have let the chickens roost in trees with no night deaths. I let them do that for a year or two before training them back into a coop. Even though they were doing fine in the trees I wanted them in the coop so they would lay eggs in the nest boxes. Another reason for the coop is for the hens raising babies. If they are roosting in trees then when they go broody it is usually somewhere inconvenient and unsafe for them. Coops are not totally needed in my situation, but they have their uses, and they make my operation legal in the eyes of the city.

I think if you're raising a short-term group of meat birds then a coop may not be necessary. However, if you're raising a group of laying hens which may spend several years on your property you will appreciate having them trained to use a coop. For many of the reasons others listed the coop makes your life easier - collection of eggs is streamlined. Also, having a coop means that you can leave the chickens "cooped up" if you will be out of town overnight or for a short period of time. A lot of time chickens or pet dogs will alert you to predator problems but you have to be within earshot of the yard.

The coop can and is mainly for there protection
I had 40 chickens sleeping in trees and in one night they were all taken by raccoons
and yes you do have night time predators in the city and surrounding areas
My father in law trapped a raccoon every night and he lives in the city.

Because you want to find their eggs and keep your chickens. You only think you have no predators. A chicken buffet will show you otherwise

Hawks love to snack on your babies.... we all have predators locally..... i have lost 20 plus in the last 2 years and i have secure coops.... free ranging, and forgetting to close the doors are my issues.