His expedition was completed after a total of 17 months, Beebe and Blair crossed the Pacific to San Francisco, then crossed the United States to return to their home in New York. Their expedition had obtained live or stuffed specimens of nearly all the pheasants he had sought, and also produced extensive notes about their behavior. Some of these pheasants, such as Sclater's impeyan or Himalayan monal, had never before been seen in the wild by Americans or Europeans. Beebe's observations of sexual dimorphism in pheasants during this expedition led him to become the first biologist to correctly understand the mechanism by which this aspect of sexual selection operates. based on his observations he also proposed a new evolutionary model of pheasant ancestry, involving a period of rapid diversification followed by more typical and gradual changes. Although this evolutionary model is now taken for granted, in William Beebe's time it was a novel idea.