Among keepers, Elmer the bighorn sheep was known as “...the most pugnacious sheep imaginable. ...Chances are that when you approach his corral he will come trotting over with his head cocked to one side...to look you over. If you pass inspection, he’ll invite you to come in and wrestle.” At the time, Elmer and his mate Irma were the only Nelson’s bighorn sheep in a zoo anywhere in the world. The U.S. Fish and Wildlife Service had placed them with the Zoo for breeding; the bighorn sheep population had been declining for more than two decades, and the species’ future was at risk. In 1949, Elmer and Irma had a little lamb—the first of this species born in a zoo.