Sorry I missed out on all the fun.
Bears are omnivores! Eat both meat and veggies. Grizzlies eat more meat and black bears less. Grizzlies largely eat MOTHS when they come out of hibernation, followed by ground squirrels (hence the big "hump" of muscle between the shoulders). Black bears, (evolution-wise) are meat eaters reverting back to plants.
Black bears are more likely to kill and eat you than grizzly. A grizzly is like a Marine=remove the threat (often with prejudice!) and move on. Comparing a black bear to a grizzly is like comparing a Sherman Tank to the Enterprise!
Brown bears are now thought to be merely better-fed grizzlies. Texas== black bears are now Ursus americanus==Grinnell once described 81 "species" of black bear in N.A. BTW Polar bears and the panda are now considered in the genus "Ursus" also--based on genetic relationships.
Many, if not most, livestock attacks are scavenging on naturally killed sheep. Although there are "rogues". Ranchers and herders don't get reimbursed for natural deaths ("rural welfare"). Interestingly, one of the only two "proven" wolf attacks on humans was likely a predatory black bear.
Biggest black bear I've seen is about 650lbs (Calif state record). The biggest I've personally handled was 429, when we trapped him. Most California yearlings were 200-250 lbs.
My personal opinion is that losing livestock to predators is part of the cost of doing business if you graze on public land for nearly free. It should be noted that, in Ireland, foxes are blamed for killing sheep. But, everywhere (including New Zealand which has no natural predators on sheep), the overall mortality rate is about the same.
Take home: Both can be killers. Both are hard to stop, grizzlies more so. They are incredibly fast! (I've been charged-I KNOW how fast they can be!). There are no answers=make the choice that seems best to you.
My choice: Pepper spray, followed by a hot loaded 45 Colt Blackhawk (300 gr hardcast at about 1200 fps)
