I'm assuming though the pleather would have passed through his system by now, no? What would the droppings indicate?
Well, that depends. If the pieces were small and light enough to pass through without getting stuck anywhere, then you should be in the clear. He is pooping and that is a very good sign.
However, when dealing with impaction, it can happen either fast or slow. If the foreign object gets stuck and completely or almost completely blocks the GI tract, symptoms will develop immediately. But if it is something soft and stringy, like fiber or flexible plastic, it can get stuck and stop moving through the digestive tract without forming a hard blockage. Digestible food can still pass by, but the foreign matter isn't moving and it isn't digestible, so it just kind of hangs out in there until it eventually gets knocked loose ... or accumulates enough other junk to cause a partial or complete blockage. In a bird, this usually occurs in the crop. With chronic impaction, you might notice that your bird is losing weight and appears malnourished. In some cases, a partial blockage will resolve on its own, but sometimes it will be necessary to go in and remove the blockage surgically, especially if symptoms of acute blockage develop.
I had a bassethound years ago who used to eat rocks. We lived on a gravel bar and the soil in our backyard was full of round river rocks, some as big as your head, most about the size of golf balls or smaller. Perfect size for my weird dog to eat and end up at the vet for emergency surgery ... on five separate occasions.
When Wally would eat the wrong rock, it would block him up immediately. He would stop eating, throw up until he couldn't throw up anymore, and his belly was very tight and bloated. Surgery was necessary to retrieve the rock. We ended up with a jar full of them, despite our best efforts at "rock-proofing" our house and yard. There was one time when he looked a little off, but not as bad as usual, so we fed him apple-flavored Metamucil biscuits until he started feeling better. I suspect he had a partial blockage that time.
Here is an article discussing acute and chronic impaction:
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