Fire crews in Alaska are currently battling two large forest fires in the Yukon Delta National Wildlife Refuge, in the southwest part of the state. The fires were started by lightning and have burned ~63 square miles of the refuge, which is an important nesting ground for waterfowl. Currently, the fires are not threatening human lives or establishments. Though unusual, tundra fires are not unheard of in the southwest portion of the state, where dry and warm winters combined with spring lightning storms can ignite tundra wildfires. Fires are less common in the northern portions of the state, where lightning is rare. Even these areas experience fires occasionally, such as the 2007 wildfire that burned ~400 square miles in the Brooks Range of the North Slope, about 400 miles north of the current fires.