There is no notification for this currently, but that may be in the works eventually (see this page).
I had this same issue with bison in the Black Hills. I wonder if it’s someone who thinks that the reintroduced populations don’t count as wild (which is probably a valid argument, but up for debate). You can always click the number next to the thumbs down to see which user marked it as such. You can then mention them and ask why. (Sometimes I accidentally mark an observation as captive/cultivated in the Identify window when trying to select different photos.) In my case, someone else came along and up-voted it so I’d guess there’s a bit of community disagreement going on.