Efforts to find a missing day hiker at Mount Rainier National Park moved into day four Wednesday with dog teams helping ground crews while searchers looked from the air, as well.

Plans called for searchers looking for Edwin Birch, 64, of Tacoma, Washington, to focus in the general area where he was last seen. Mr. Birch and his son were hiking the Wonderland Trail in sections, and early Saturday the two set off at opposite ends of a 19-mile section between Box Canyon and White River, according to a park release. Mr. Birch had dropped his son off at the White River trailhead, drove to the Box Canyon trailhead, and left the car there while he hiked towards the White River trailhead. 

At approximately 3:30 p.m. Saturday the two met midway on the trail near Indian Bar at around 6,600 feet above sea level. Late that evening, when the son drove back to the White River Trailhead, there was no sign of his father.

Park officials said the search area is in steep, rugged terrain with snow cover starting at the 6,000-6,500-foot level. This section of the Wonderland Trail is snow-covered above 6,300 feet and patchy at other locations, park staff reported.