Normal Versus Bait-Laden Prairie Dog Feces

This image was taken during field tests to determine the effectiveness of a USGS-developed oral sylvatic plague vaccine (SPV) to help immunize prairie dogs against plague. The SPV is administered to wild prairie dogs via a brightly colored bait. After the bait is eaten, the animals' excrement takes on the color of the bait. In this image, normally-colored excrement (left) is compared to bait-laden excrement (right).

If successful, the SPV could help protect endangered black-footed ferret populations in the western U.S. because the ferrets rely on prairie dogs for food. The SPV project is a collaboration of over 30 organizations and agencies.