United Airlines says a jetliner has returned safely to the Denver airport after a bird struck one of its engines shortly after takeoff. Airline spokeswoman Megan McCarthy says the engine that was struck continued to operate and the second engine wasn't affected. None of the 151 passengers and crew was injured. The Boeing 757 had just taken off for San Francisco on Tuesday when the bird strike happened. McCarthy said the pilot's decision to return to the airport was a precaution. A US Airways jet splash-landed in New York's Hudson River on Jan. 15 after a collision with a flock of birds knocked out both engines. All 155 aboard survived.