Here are some photos of male monarchs I saw patrolling irrigated horse pastures in Big Pine and Bishop, Calif. on Aug. 6 this year: http://i85.photobucket.com/albums/k75/4af/bigpa.jpg
http://i85.photobucket.com/albums/k75/4af/bisbroc.jpg
Here's an aerial photo of the exact same field in Bishop http://i85.photobucket.com/albums/k75/4af/bisbrocb.jpg
As you can see from the aerial photo, Bishop is surrounded by arid sagebrush desert but monarchs are common in Bishop anyways thanks to the abundance of irrigated horse and cattle pastures where well hydrated milkweed can thrive.