Salt River Curiosity

During the cooler months, bands of the Lower Salt River wild horses tend to congregate in one area. On this morning, something caught the attention of this entire band. What could it have been?

11" x 14" photo matted to 16" x 20" framed size and 8" x 10" matted to 11" x 14".  Each photograph is signed on the mat by the photographer and shrink wrapped.