[netfire]

I did some quick searching and found a Newsweek article with the same claim referencing a study where:

"White made that estimation by watching grizzlies with a scope for up to 14 hours per day, while writing his dissertation on the animals at Montana State University-Bozeman. He also counted how many dead moths he could find in each bear “scat,” or pile of poo, and multiplied that by the number of times these bears defecated."

http://www.newsweek.com/grizzly-bears-can-eat-40000-moths-da...