He recorded the first notes of a horned lark on the sixteenth of February. This unseasonable good weather induced him to stay a few weeks with a band of Pawnee camped just south of the Niobrara River. One morning he volunteered to go out with two men to look for stray horses. They found the horses grazing near an island of oak and ash trees on the prairie, along the edge of the river. When he saw the current and quicksand Foster was glad the horses had not crossed over. On the way back, writes Foster—little of his last journal survives, but some fragments relevant to this incident are preserved—the Pawnee told him that the previous summer the upper Niobrara had disappeared. At first Foster took this for a figurative statement about a severe drought, but the other Pawnee told him, no, the Niobrara had not run dry—in fact, the spring of 1843 had been very wet. It disappeared. That Foster took this information seriously, that he did not treat it with skepticism or derision, was characteristic of him.
