I've always thought that chickens eat all bugs. I suspect that they would eat earwigs. I can't think of a reason why they wouldn't.
As for the nocturnal aspect: suppose you have some leaf litter on the ground. I can picture a lot of earwigs there under the leaf litter during the day and the chickens turning it over to eat all the bugs.
is there any species that won't eat the young crops/seedlings when roaming? I'm open to any kind of bird.
Dunno. But I do know that if your chickens are in an area where they have eaten all the bugs and they have lots of greenery, then they are powerfully bug hungry. Then turn them loose in your garden an hour or two before sunset. They will race through, eat the bugs and then go back to the coop to roost for the night.
living in town (~100'x100' lot), the birds would need to be contained to my yard and specific sections at that. I hate to have all my fencing high though (existing is 6-7' tall). Could I get away with some fencing in the 3'-4' tall range?
With heavy breeds like buff orpingtons you can have the shorter fencing.
lastly, which books on the subject are recommended? Though we had chickens on the farm, little attn was paid to them, i.e., my knowledge on the subject is thin.
Ooof. I have read a lot of books and I don't like most of them. Maybe there are some newer books that talk about raising chickens in the
city. For raising a hundred or more, I would recommend salatin's book. I do want to say that I am completely against the
chicken tractor stuff. If you read through this forum, you will find my rants about how I think chickens should be raised, including in the city.