A duck hunter was found dead inside a shelter Tuesday evening at the Ridgefield National Wildlife Refuge.The 54-year-old man, who had a history of medical problems, presumably died of natural causes, according Clark County sheriff’s Sgt. Randon Walker. His name was not released, pending family notification. The man went to the refuge off South Hillhurst Road around 5 a.m. to use a duck blind. When he didn’t check out at dusk, as hunters are required to do, a manager went to the blind and found the man face-down, Walker said. An aggressive dog inside the blind wouldn’t let the manager near the man. He called 911 to report the death at 5:56 p.m. Ridgefield police got the dog out using a catch pole, and then paramedics confirmed that the man was dead. A duck he had shot was inside the blind with him. Investigators with the sheriff’s office believe the hunter was alive until at least 7 a.m., Walker said. The dog was turned over to Critter Gitter, an animal control company, until a family member could retrieve it. The Clark County Medical Examiner was also sent to the refuge to help investigate the death.