Hi Daniel...I'm very happy and appreciative that you are fostering this lost pet until you can find the proper owner...This is a very loved pet that got loose Daniel, someone is missing him very much, they are most-likely devastated right now, and they are probably putting ads for their "Lost Gold-Capped Conure" on places like Parrot911 and your local Craigslist sites (on Craigslist you go to your local page, then to Community, then Pets)...
Have you put up an ad on on Parrot911 and your local Craigslist saying that you have found him? And have you also checked both of these sites for someone looking for their bird? If not, please do so right now, as you may find his owner's ad right away...
I'd be happy to help you look to, if you tell me what city and state you live in, I have searched both Parrot911 and Craigslist to help reunite many owners with their lost birds, so I can easily check for a a "Lost Gold-Capped Conure" ad for you, just to be sure...
***Also Daniel, you need to take him to your nearest Avian Vet/Exotic's Vet and have him checked for an Identification Chip...Most-all Exotics and Avian Vets will have a hand-held scanner that they will run over his chest/belly to check to see if his owner had a chip injected into his breast-muscle. If the scanner goes-off, it will give them his owner's name and personal information. This will not cost you a cent, they will scan him for free, so please, look-up your nearest vets that scan for bird-chips...
I know you like this bird Daniel, and again, we much appreciate you helping him out...But Daniel, this Conure not only looks pretty young yet, but he also looks like he has been very-well cared for. He's in very good feather, he's well-fed, and Daniel, you admitted already that he is "very tame and friendly"...Daniel, if this young Conure is allowing you to handle him, is being friendly and tame, is stepping-up for you, etc., that means that he is a hand-fed, hand-raised Conure, and was most-likely purchased as a very young, just-weaned baby by his owner, and has been with that owner ever since. It's unfair to both his owner and to him for you to keep him Daniel...
Parrots have the intelligence of a 4-5 year-old human child Daniel, and this guy is already extremely closely-bonded to his owner, and is missing him greatly. And I can tell you from personal experience that his owner is dying right now from worrying about him and missing him...So you need to make a very concerted effort to do everything you can possibly do to find his owner...And like I said, we can help you do so by checking for someone looking for a Gold-Capped Conure on the main websites for missing parrots...
But you absolutely need to put an ad up on your local Craigslist Daniel, and all you say is "I found a parrot outside in XXXXX (list your town that you found him in). Please call me or email me and if it's your parrot you can describe him to me and we'll go from there." This way anyone who contacts you about him will not be able to just say that it's their bird, they'll have to accurately describe him to you...So please Daniel, do this ASAP, and do the same on Parrot911...
Something else that you really need to consider and think about Daniel is that birds (pets in-general) are considered "Personal Property" legally in the United States, and if you find an animal that is obviously someone's pet and you don't make a "concerted-effort" to find the owner, meaning you don't take it to a Vet to have it scanned for a chip and to let them know that you found it and get it on record that you did so, and you cannot prove that you at the very least put-up an ad somewhere advertising that you found it, like on your local Craigslist page, it's legally considered "theft of personal property" and you can get into a lot of trouble. I've seen it happen several times, it happened just a couple of months ago with a guy who found a Cockatiel outside and put up a video on YouTube stating that he found it and was keeping it, and he had already renamed it, and was not going to advertise that he found it or look for the owner...So I don't want to see you get in trouble when all you're trying to do is take good care of this bird until his rightful-owner can be found and they can be reunited...A lot of people don't realize the laws regarding found-pets...
Again, let us know how we can help you to find his owner online, and please take him to your local Vet, report finding him so they can make a record of it, and get them to scan him for a chip....
