As part of the national Inventory and Monitoring Program of the National Park Service, the Klamath Inventory and Monitoring Network and Klamath Bird Observatory established a protocol to monitor long-term status and trends in landbird populations at National Park units in southern Oregon and northern California. This report examines detection probabilities and estimates densities using data from the first sequence of surveys in the five larger park units in the Network: Crater Lake National Park, Lassen Volcanic National Park, Lava Beds National Monument, Redwood National and State Parks, and Whiskeytown National Recreation Area.