The five smallest subspecies (hutchinsii, tavernerii, minima, leucopareia and the extinct asiatica) of Canada Goose (Branta canadensis) were recently split by the American Ornithological Union into a separate species, Cackling Goose (B. hutchinsii). This bird, found by Jason Forbes at the UMass Field Station in Waltham, was initially identified as the "Richardson's" form of Cackling Goose (B. h. hutchinsii). However, field guide author David Sibley studied the bird and suggested it is probably the "Lesser" form of Canada Goose (B. c. parvipes), prompting a number of local birders to erase Cackling Goose from their life lists. Either form would be a rare straggler to Massachusetts. Since then, the identity of this bird has been debated on the ID Frontiers email list where a number of experts have suggested that it appears to be the "Taverner's" form of Cackling Goose (B. h. taverneri), which would be an extraordinary rarity in the state.