Very rare in late fall and winter but previously overlooked. In most plumages, almost identical to RUHU. Only safely separated from RUHU by narrower tail feathers with more extensive white tips. ID: Ad ?: narrower tail feathers and broadest in imm ? - it is always necessary to age and sex birds for comparative purposes. This ID is extremely difficult in the field but is possible. Allen's molts earlier so usually looks faded by late fall and averages more extensive red on rump. Ad ?: greener back and crown than RUHU.