Wyoming Game and Fish field personnel collect a variety of data throughout the year to determine big game population trends. One of the more telling pieces of data providing a picture of future population trend in mule deer is the fawn winter survival data, or the change in ratio survey. It meaures the number of fawns (per 100 does) both at the beginning of winter and at the end of winter. This year's results show just how variable the winter impacts were in western Wyoming. 

For the Sublette Mule Deer Herd near Pinedale, the change-in-ratio data for 2018-19 showed a 68% fawn loss for the Pinedale Front (of the Wind River Range) and a 36% fawn loss for the Pinedale Mesa Complex. Typically, deer and pronghorn can find milder winters the farther south they go, but this year it was the opposite. The harder winter conditions were to the south. Also, the spring migration north along the Pinedale Front was notably later this year.