Joel Sartore prepares to photograph El Segundo flower-loving fly (Rhaphiomidas terminatus terminatus). With fewer than 100 individuals left on Earth, this species is as close to extinction as you can get. This animal was thought to be extinct since the end of the 1960s but a small remnant population was discovered in the early 2000s.
One of fewer than 10 woodland caribou (Rangifer tarandus caribou) in US zoos, Costello the caribou would stand patiently anywhere in exchange for a reward of grape leaves. Meanwhile in the wild, woodland caribou are nearly absent from the lower 48 states because they rely on old-growth forest habitat. Just a few holdouts still cross from Canada into northern Idaho and Washington. The total U.S. population is 40 individuals. (US: Endangered)