The recently-published book, Icelandic Sheep--Colorful All-Rounders, suggests that the rare gray-mouflon allele is possibly extinct now in Iceland; indeed, from the small number of crosses that Adalsteinsson was able to make, it was a rare occurrence in the flock in 1970.  In North America, on the other hand, the population of SGGM sheep is expanding, thanks to the breeding efforts of an increasing number of farms.