In a federal appeal court government lawyers have said that the National Park Service acted properly when it ruled out using wolves to control the elk population in Rocky Mtn National Park.  The wildlife advocacy group, WildEarth Guardians have sued the Park Service because they said the Park Service did not give enough consideration to the use of wolves.  Elk population has become problematic since many of them are overgrazing leaving other animals without enough food.  Not many natural predators are left there and hunting is prohibited in all national parks.