As the residential and recreational development in western Kittitas County increases, as well as interstate travel and commerce, the need arises to expand the interstate highway system 5 to accommodate the increase in traffic volume. With average traffic volume increasing by 3% per year, there are plans to expand Interstate 90 (I-90) from 4 lanes to 6 lanes from Hyak east to Easton (I-90 Snoqualmie Pass East Report, Washington State Department of Transportation 2004). Currently, I-90 is thought to be an ecological barrier for some terrestrial species, which may prevent or inhibit movement and genetic exchange across the corridor. For more mobile species such as elk (Cervus elaphus), mule deer (Odocoileus hemionus) and large carnivores such as black bears (Ursus americanus) and cougars (Puma concolor), there is also the concern of public safety from vehicle collisions with these animals. To decrease the affect of I-90 as a barrier to ecological connectivity, wildlife corridors are being considered in the I-90 expansion plan. Identifying and locating these wildlife corridors to facilitate animal movements is currently in question.
To identify areas for potential wildlife corridors along Interstate-90 (I-90) and state highways (SR), we analyzed cougar movements and 95% fixed kernel home range estimates from Global Positioning System (GPS) collar locations of collared cougars on a 3,657km 2 area of western Kittitas County, Washington from 2001-2004. A logistic regression model for both winter and summer was developed to determine relative probability of use by cougars for topographic and land cover characteristics. Our objective was to use existing Global Positioning System (GPS) locations for collared cougars to identify Geographic Information System (GIS) attributes that are correlated to cougar crossings sites and travel corridors used by cougars along I-90 and state highways in western Kittitas County.