I'd not pay too much attention to Wiki in this case. The original treaty with Mexico unless it has been altered since did not include blackbirds but rather crows. It was to protect a somewhat rare Magpie living in Mexico but that some times crosses the border into the US. It was poorly worded and didn't just protect the Magpie but included the entire family which includes crows, rooks and ravens.
Black birds, starlings, cowbirds, redwing blackbirds and grackles was not and so far as I know still are not covered under that treaty. I realize some states protect them but those of us living in the south are not among those.
Anyone who wants to can put bad info on wiki as it's all user supplied info and not all of it is even remotely correct. The treaty you linked to is not even the one that restricts hunting of crows that is between the US and Mexico. The one you list Tim is the international one that is the reason we have the restrictions we do on birds like Doves and waterfowl. The one on crows is completely different. Black birds other than crows which happen to be black are not covered.
Most states across the souther tier of the US all the way from east to west coast have no seasons and no bag limits on "blackbirds" further defined at times as starlngs, cowbirds, grackles and rarely redwinged blackbirds altho most times the latter is not specifically mentioned but just assumed covered under the generic blackbird name.
