There is no such thing as an "official regional bird." There is simply a recurring feature in Pokemon generations of an early-game bird Pokemon that happen to mostly be Normal-Flying type. This has never been acknowledged by the Pokemon Company, and other unofficial regional Pokemon exist, like "regional bugs" and "regional annoying creatures".
Past candidates of "regional birds" tend to mainly include Pidgeot, Noctowl, Swellow, Staraptor, Unfezant, Talonflame, Toucannon, and Corviknight. All but Talonflame and Corviknight are Normal-Flying type.
Due to the lack of an obvious early-game Normal-Flying type in SV, many players argued over what Pokemon was considered Paldea's "regional bird." It seems to be widely accepted that Wattrel and Kilowattrel are the "regional birds" of Paldea. Some argue that Wattrel is not found early enough in-game to be considered the "regional bird" and the lack of a Normal-Flying type in the evolutionary line rejects it from the role. In this case, one might say Talonflame is the "regional bird" of Paldea, as it is found first in the Paldea Pokedex, and has a Normal-Flying type in it's evolutionary line.
