Individually, the underwing coverts can variety from all darkish to off-whitish (most usually far more heavily streaked with brown) which contrasts with a distinctive black patagium marking. Even in youthful crimson-tails, the tail may be a to some degree rufous tinge of brown. North America normally have noticeable distinct markings that are absent in red-tails, irrespective of whether the rufous-brown "beard" of Swainson's hawks (B.