St. Andrew Beach Mouse (Peromyscus polionotus peninsularis)
6,000 (Estimates range from 3,500 to 6,000).
Image: Joel Sartore/National Geographic [larger view].
Joel Sartore has shared some of his work on this blog before, so I am thrilled to tell you that National Geographic also appreciates his exemplary work. You can view more endangered animals of the United States that were photographed by the talented Joel Sartore here at National Geographic online. All images appear here by permission of National Geographic online.