GEN. CHAR. Size varying from medium to very large; head with or without
ear-tufts. Bill black; iris yellow. Two to four outer quills with their
inner webs emarginated. Third or fourth quill longest. Bill very robust,
the lower mandible nearly truncated and with a deep notch near the
end; cere gradually ascending basally (not arched) or nearly straight,
not equal to the culmen. Tail short, a little more than half the wing,
slightly rounded. Ear-conch small, simple, without operculum; the two
ears symmetrical.
Subgenera.
=Bubo.= Two to three outer quills with their inner webs emarginated.
Ear-tufts well developed; loral feathers not hiding the bill, and the
claws and terminal scutellæ of the toes exposed. Lower tail-coverts
not reaching the end of the tail. (Type, _B. maximus_.)
=Nyctea.= Four outer quills with their inner webs emarginated.
Ear-tufts rudimentary; loral feathers hiding the bill, and claws and
entire toes concealed by long hair-like feathers. Lower tail-coverts
reaching to end of the tail. (Type, _N. scandiaca_.)
The species of this genus are mostly of very large size, two of them
(_B. maximus_ and _N. scandiaca_) being the largest birds of the family.
They are nearly cosmopolitan, and are most numerous in the Eastern
Hemisphere.