by Betsy Marston/Writers on the Range NORTH DAKOTA Everyone knows that ravens can manipulate sticks as tools, and that squawking magpies enjoy teasing dogs and cats, but who knew that cows – with their bodies alone – could make pipes spill natural gas? In Bismarck, North Dakota, one cow apparently did just that, simply by trying to satisfy an itch or maybe indulging in idle curiosity. The animal rubbed on a valve until it opened, thereby spilling some 20 barrels of natural gas “condensate,” a by-product of natural gas production. Dave Glatt, North Dakota’s environmental health chief, said cows “just…