I thought of a few more. Not really strange, but unusual.
Once I saw what I think was a largemouth bass swallow a baby duck. Was living in a condo in NJ at the time. Mother duck with six babies, and she was fussing like craze sticking her head under water. I figured snapping turtle. But then there was a huge splash and there were 5 ducklings.
I came back an hour later with a spinning rod and landed a 5 pound largemouth from that little runoff pond. I didn't cut it open to see if it was the culprit though.
About 10 years ago, I caught a largemouth bass that had swallowed a black bird. When I was unhooking it to let it go, I noticed what looked like a couple leaches in it's throat. I grabbed one, and it was actually a black feather, still attached to the bird in the fish's gut.
It was likely a fledgling Red wing blackbird. They were nesting in the cattails.
And about 20 years ago, While everyone was watching the the show in the main tank at Sea World Ohio, I saw a fledgling sparrow fall into the whale tank off to the side. The killer whale circled around and sipped that tiny sparrow like a trout sipping a midge.
Speaking of things eating fledgling blackbirds, my dog swallowed one, once. I say once, because I stopped him from swallowing it a second time, after he horked it up in the kitchen.