Federal scientists say this massive move to shore by walruses is unusual in the United States. But it has happened at least twice before, in 2007 and 2009. In those years Arctic sea ice also was at or near record low levels.
Scientists are most concerned about the one-ton walruses stampeding and crushing each other and their smaller calves.
U.S. Geological Survey walrus research site: http://alaska.usgs.gov/science/biology/walrus/index.html