If you want a constant supply of
local pigeons you want to do a few things to make sure it's
sustainable in all ways;
1. Housing- your pigeons will be way safer if they have a solid roof over their nesting place. Also, designating a prime nesting site means they won't be doing so in your carport, barn, sheds, etc. as they
poop A LOT. A house for them can look like anything and be made from anything, but if you want them to use it it should have nice places to nest in it (5 gallon buckets on their side filled with
hay work great), and it should have an entrance up high. They will prefer entering from up high and it's just safer for them. You keep a lot of predators out by lifting the entrance at least 4-5' off the ground. You can make a walk-in door if you want. Mine seem to love nesting on the ground, or UNDER the ground if they can manage it. They'll use old rabbit holes as nest sites if you let them. A
bucket on the ground is easy access. They'll hide under a slab of
wood with 4" underneath it. They'll nestle behind a tote or box up against a wall. They want to be hidden
2. Feed- pigeons are grainivores. They do well on a high protein diet. Feeding them roasted peanuts and old bread will probably sustain them, but their poop is going to stink really bad and probably be really runny. Their gizzards are built to crush and grind hard whole grains, like wheat berries for example. Feeding them a highly processed grain product will ultimately lessen their health, and the health of their squabs. Squabs are raised on crop
milk, which is a pre-digested liquid mixed with whole softened grains. Bread can't replicate this in any way. And I personally wouldn't want to feed that to animals I'm eating. Would it kill them? Probably not, especially if they're free ranging.
3. Wild food- homing pigeons can be raised and trained in two ways. The first is by nesting habit. 2-3 nests of squabs in a safe location should 'home' them to a new site. Second is by food. They can travel up to 300 miles in a day to a prime feeding site. The farther they have to travel for good food, the more you're going to lose to predation. Accordingly, they can be trained for one-way or two-way transit between an established and memorized nest site and a feed site. 300 miles, from what I've read, is about the limit of their mapping and flight capacity, if you're going to use them for communication. Anyway, planting wild food for them is the best
permaculture approach. Plant a plot of grain and legumes, like lentils, sunflowers, and grain grasses. Amaranth, millet, teff, sorghum, etc etc. They will feed themselves when the harvest is high and it will help keep them home and safe.
4. Failsafe stock- I would recommend keeping 1-3 breeding pairs, minimum, in a pen or aviary in case your free ranging flock gets decimated. Either that or find someone local you can rely on to replenish. A breeding pair, if enthusiastic, safe, and well fed, can produce a set of squabs every 3 weeks, 9 months or more out of the year. Usually nests contain 2 eggs, and usually both squabs hatch. Rarely you'll get 3 eggs, sometimes you'll get 1 egg. If you get a 1 egg clutch and you want production, you can take the egg away and either add it to another new nest, or destroy it (sadness, I know) so the hen will start laying again and hopefully lay at least 2 eggs. Squabs are ready to eat in about 4 weeks.
5. Breeds- the American homers are extra large. Mine dress out around a pound and have ample extra fat. Selecting stock that have wide, broad chests will increase your meat production. Racing breeds are often slender and have less meat.
6. Predators- the biggest predator for the pigeons are birds of prey. Second might be cats, though the adults are fairly safe from cats as long as the cat isn't snatching them off the roost at night. Squabs are cat bait though. Once a hawk or
owl learns there is a supply of pigeons in your area, they will stay very close. More agile, lean racing breeds will fair better than slow heavy meat breeds in this case. It's possible to lose several birds in one day, watch out! Giving them safe housing and feeding them in a sheltered area will help ensure their survival. Integrating them with chickens can help, too, as the chickens will have eyes on the skies. Don't house them together if you want full meat production, sometimes chickens ruin and tamper with pigeon nests and pick on young squabs that can't fly.
I can't find my photos from last year, but I grew a garden in the pigeon pen, along with foodstuff for them. This year I will be expanding to two aviaries. I just bought a whole bunch of new stock and breeds and will be selectively refining the subsequent squabs, but there's way too many in their aviary right now in the mean time!
EDIT:
This year we're going to hybridize our setup. Now that I've got over 10 breeding pairs of mixed genetics, we can 'afford' to lose a few birds letting them out to fly. We'll make a chute for them at the highest point on the aviaries (since they don't do well with being expected to
land on the ground and enter through a gate, as we've learned), and let them out to fly in the evenings when most the birds of prey are in bed for the night. We wouldn't mind a free flock, but they would get wiped out really quickly, and also turn all of our outbuildings and roofs into toilets >_<