Probability of foot and mouth disease infection of winter-distributed white-tailed deer in an area in south Texas, predicted by 100 simulations of the Sirca model. Each simulation was initiated at the same 5 index herds (•, represented as 1 km² pixels) in either the Edwards Plateau (upper) or South Texas Brush (lower) ecoregions as infected. Probability of infection (per pixel) is shown. (A color version of this figure is available at www.vetres.org.)