Although there can potentially be many ways CWD spreads geographically, the species own behaviors are almost certainly the primary cause. First, CWD spreads primarily through close contact with body fluids, especially saliva and urine. And what is the primary way deer communicate with each other? By interacting through saliva (licking branches) and urine (scrapes). Second, deer - especially bucks - move around geographically. Bucks can have far reaching travel patterns during the rut. Third, some young deer disperse great distances from the region in which they were born. And the more open the habitat, the farther they disperse. In southern Michigan, yearling bucks were documented dispersing over 100 miles from their birth range.
CWD spreads through a local population through normal behaviors, and then is spread geographically through range-expansion during the rut and also by dispersal of younger deer.
