Really, what does anyone know about grizzly bears?

After watching a PBS special on grizzlies, I thought I would share in 5 scintillating points!

• In the past, grizzly bears roamed all of western North America. Now, not so much.
  
• Why? Because humans killed them until there were only maybe a 100 left in the Yellowstone area.
• But since people really like looking at bears, Yellowstone developed bear feeding areas. To get the bears there, they dumped all the garbage from the campers into the feeding zones.
  
• After generations of this domesticating action, Yellowstone figured out that it wasn't doing the bears any good. In the early 1970's, they removed all dumping/feeding grounds.
• Naturally, the bears were perplexed and began scavenging in camps (they'd forgotten how to hunt). Unfortunately, many bears were destroyed, i.e., killed for trespassing. What happens when a bear attacks you?
  
  
• Thankfully, resilient bears soon remembered how to survive in the wild. They have grown to over 350 breeding females in Yellowstone and the question now is: are there too many bears?

That's the recap. Now the interesting thing for me is that bears disappear in the high summer. Where do they go and what are they doing? Check this video out to learn more.

Update: Results of landmark montana grizzly bear study (USGS)