Wildland Fires Act of 2017 This bill requires the Departments of the Interior and Agriculture (USDA) to conduct a cost review each fiscal year of each wildfire covering an area greater than 100,000 acres. Appropriations for wildfire management operations in USDA's or Interior's Wildland Fire Management accounts that are not expended for a fiscal year may be available for wildfire risk reduction projects on federal land. Interior and USDA shall: (1) publish a map depicting at-risk communities (as re-defined by this bill), including tribal communities; and (2) furnish financial assistance to such communities adjacent to federal land for wildfire planning and preparations. Interior and USDA shall: (1) establish a pilot program to reduce the risk of wildfires to communities in the wildland-urban interface and reestablish natural fire regimes outside such interface, and (2) implement the program to treat specified federal land composed primarily of ponderosa or Jeffrey pines by September 30, 2027. The bill establishes the Pilot Monitoring Committee to monitor the impacts on wildfire risk and the ecological effects of the projects being implemented under such program. Interior and USDA: (1) may issue stewardship contracts or enter into stewardship agreements for up to 10 years to conduct prescribed fires on federal lands, and (2) shall establish a pilot program for awarding contracts or agreements of up to 20 years to carry out restoration projects or hazardous fuels reduction projects on federal lands. The National Forest Foundation shall establish a program to certify as a collaborative a group of interested persons that is interested in assisting USDA and Interior in increasing the quantity of projects or activities such departments carry out on an individual unit of National Forest System land or public land administered by the Bureau of Land Management in accordance with the applicable management plan.