Personally, I'd nibble one. They look like crabapples to me, and I'd see if I liked them. Teeny tiny bite in case they are sour. But they look like apples to me, and as far as I know, there are no toxic apples out there except Manchineel
Wikipedia Manchineel Manchineel grows in swampy brackish water and has sap that burns you. Birds and animals will not eat them, if the birds like your apples, and you are not on the coast in a swamp, I'd say taste them.
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