The United States Department of Navy (Navy) maintains the Naval Weapons Systems Training Facility (NWSTF) Boardman in Boardman, OR. The Washington ground squirrel (WGS; Urocitellus washingtoni) occurs only in the Colombia Basin east and south of the Columbia River, and its geographic range and abundance have declined over the last century. Significant portions of the remaining WGS populations reside within the boundaries of NWSTF Boardman. To meet the changing needs associated with new threats and new definitions of military readiness, the Navy and the Oregon National Guard (ORANG) must continue to develop new weapons systems and new innovative training regimes. To that end, the Navy and ORANG seek to update and enhance the training capabilities at NWSTF Boardman. Key to the decision-making process is understanding and minimizing the environmental impact of proposed changes, including effects on the WGS population.
The Navy engaged a team comprising Michigan State University, LimnoTech, and Kern Statistical Services (Kern) to design and implement a field survey of the NWSTF. A primary objective was to estimate numbers of WGS burrows and burrow density per unit area within specified locations selected for changes in military training and operations, within identified strata, and for all of NWSTF Boardman. A second objective was to provide high-quality information to decision-makers concerning any year-to-year changes in abundance related to changes in facilities and training activities. Significant challenges included the large scale of the site (approximately 6 miles by 12 miles), and the difficulty of visual observation of WGS, who emerge only briefly from hibernation for a few months in the spring, spending little time outside their burrows.
The project team conducted baseline field surveys in 2014 and 2015, and compiled critical baseline data in advance of updates in NWSTF facilities. Through the use of cameras, much was learned about identifying dens occupied by WGS (as opposed to other species) and about the reliability of indicators of occupation that have been widely cited in literature. LimnoTech and its subcontractor Kern did much of the planning of the survey, developed a database of information obtained, and are engaged in evaluating and synthesizing the results. A baseline assessment will be provided to the Navy, and can provide a basis of comparison for future surveys.