The right lens at the right time I guess, and you sure chose the right one here. You clearly have a good eye for timing and composition, @Arizona Docent. This photo has a great combination of animals, landscape and sky. Superb and stunning photograph, many thanks for sharing it with us here.
Thanks. The other half of the herd was behind me about the same distance. To get this shot I had to walk away from the road and between the two halves of the herd. This caused my fellow photographer (who stayed in the car with a telephoto) a minor bit of concern for my safety!