Bridges for Bighorn
Despite efforts to protect desert habitat in the southwest, major highways criss-crossing the desert are isolating wildlife into smaller pockets and hindering genetic exchange necessary to keep species healthy and resilient. Desert bighorn sheep are not exempt from this impact; they may be agile and swift, but they are no match for several lanes of speeding cars and semi-trucks, and they tend to shy away from culverts that cross under highways. Biologists have already noticed that desert bighorn sheep populations in the Mojave and Colorado Deserts are becoming genetically isolated because the region's major highways - such as Interstate 15 and Interstate 40 - and other human developments pose a barrier to sheep movement from one range to another. According to a 2005 article in Ecology Letters , biologists found "a rapid reduction in genetic diversity (up to 15%)" among desert bighorn sheep resulting from "as few as 40 years of anthropogenic isolation. Interstat