A sloth of bears

I was watching a pleasant action drama, Zoo, last night.  At some point in the dialogue, the zoologist referred to a sleuth of bears for a pack of bears.  I am not sure I have heard that collective noun before.  A little googling reveals that a sleuth, or a sloth of bears is indeed a proper collective noun of bears.  

©2008, Tom Sears

James Lipton in An Exaltation of Larks shines some light.

A Sloth of Bears

When Dame Juliana wrote a Sleuth of beeris in The Book of St. Albans, she opened the door to a host of errors.  Following doggedly in her footsteps, generations of compilers confused her sleuth with the sleuth in a sleuth of hounds (q.v.).  The "Lover of the Arts" who revised the ninth edition of Dr. John Bulloker's English Expositor, 1695, attached the term to a "company of wild boars."  In 1611, George Turberville got it right again: Not sleuth of bears, but "a Slowth of Beares.  The are so heauie that when they be hunted they can make no speed but are alwaies within sight of the Dogges . . . when they wallow then they go at most ease."

Sleuth and sloth are both correct collective nouns for a group of bears.  Even dancing bears.

Dancing Bears by William H. Beard