First, please post photos of the found bird, but never share photos of that reveal: whether or not its wings are clipped, and if it has a band on its leg. These are two things that can be used to identify an owner.
You should post to all of these places in attempts to locate a found bird's owner:
-local lost and found pet groups on Facebook
-craigslist.org (post in the 'Lost and Found' section AND the 'Pets' section)
-join and post to Nextdoor.com
-contact your local shelter with a photo and description
You should also print out fliers that say "FOUND BIRD" at the top; these should be posted at as many gas stations and busy street intersections you can manage within a 5 mile radius of the bird being found. Be sure to specify in ALL your postings that proof of ownership is required, owner is expected to reimburse finder for all vet costs incurred, and you are NOT looking for a home for the bird. This should keep any fake "owners" away for the most part.
SCREENING POTENTIAL OWNERS
These are questions I expect potential owners to be able to answer for me when they are claiming a found bird:
-What area was your bird lost in?
-What date was your bird lost?
-Was your bird's wings clipped or was your bird flighted?
-Was your bird banded (if so, please provide the band number)?
-Where is your bird's favorite place to perch?
-Does your bird like to receive scritches (head pets)?
-Where are your bird's lost ads posted (please provide links or locations posters are)?
-Please send photos of your bird so I can compare them with the bird I have to confirm or deny the possibility of them matching.
Notes regarding the above questions:
-If they say their bird was lost more than 5 miles from where the bird was found, then I'd be skeptical. Though it has happened that birds are found far away, it is unlikely because our pet birds simply do not have the stamina to fly very far before becoming winded. If the bird's wings are clipped, then it would be nearly *impossible* for a bird to travel more than a couple miles, though on a windy day the gusts can push clipped birds along and help them move along much faster. Then the bird would be whatever the direction the wind was blowing from where it was lost.
-If a bird has been missing from someone for more than a week, their bird likely was either taken in by someone already or died of starvation outside. However, I've seen it happen that someone finds a missing bird and then it gets loose from the finder's home and is found again.
-If a bird is found fully flighted, then it was definitely full flighted when it was lost. If a bird was found clipped, it was likely clipped when it was lost but there is also a chance that someone could have found the bird, clipped its wings, and then it got loose again.
-The owner MUST know if their bird bird was banded. If they answer this question wrong it is almost certainly not their bird. Bands are not easily removed so this is probably the most important question.
-If you've noticed that the bird instantly hops onto your shoulder, head, or onto a ceiling fan or windowsill (like they belong there--not a place they land after frantically flying around), then this question is very useful. The cockatiel found in RR instantly hopped onto any shoulder, so I expected an owner to understand exactly what this question was asking.
-Most birds either love or hate being touched. If you put your finger towards the birds head, it will either bite at and scream at you OR it will bow its head down to be pet. Easy to determine and the owner should know the answer.
-If they do not have any ads or flyers posted for their lost bird, I'm immediately suspicious. That means they either didn't lose the bird and are just trying to get a free bird from you, or that they didn't care enough to search for their lost bird (but if that were the case, they probably would not be contacting you).
-Almost everybody has at least one photo of their pets. They SHOULD have a picture to send you. Please save their image and go to https://www.tineye.com to make sure they didn't steal a picture from the Internet to send you.