Bill,

You're absolutely right. The dispersal rates, or bands, coincide with both age and density. If the population rates are high, the dispersal distance is great. If the population densities are low, dispersal rates are usually less, but do vary greatly based on food.

Big question here is: where did the wild deer first encounter the prions? Was it shared food/feeding area, or is this a bigger problem? Limited number of infected wild deer suggest, to me, that it was an isolated incident and there must have been some sort of shared contact. Obviously doe/fawn interaction is obvious...