Not just large but massive, with a thick neck, shaggy throat feathers, and a Bowie knife of a beak. In flight, ravens have long, wedge-shaped tails. They're more slender than crows, with longer, narrower wings, and longer, thinner “fingers” at the wingtips.
Forrest near Yellowstone River. Non-breeding juveniles forage socially and aggregate in communal winter roosts, and these appear to function as ‘information centers’ regarding the location of the rare food bonanzas: individuals search independently of one another and pool their effort by recruiting each other at roosts.
I have seen large flocks in numbers approaching 100 at this site in the past. "Rich Pickings Near Large Communal Roosts Favor ‘Gang’ Foraging by Juvenile Common Ravens, Corvus corax" http://www.ncbi.nlm.nih.gov/pmc/articles...