The area around the confluence of the Silverthrone and Klinaklini glaciers in southwestern British Columbia provides a glimpse into how the terrain traveled by Native Americans in Pleistocene times may have appeared. David J. Meltzer/Science hide caption

itoggle caption David J. Meltzer/Science

Fernandina's Flicker (Colaptes fernandinae), a woodpecker found only in Cuba. Pete Oxford/Minden Pictures/Corbis hide caption

itoggle caption Pete Oxford/Minden Pictures/Corbis

A Sandhill Crane flies in at sunset to roost for the night in the wetlands of the Monte Vista Wildlife Refuge in Colorado. Migrating along the same route they've followed for thousands of years, about 25,000 Greater Sandhill Cranes pass through the San Luis Valley in late winter every year. Doug Pensinger/Getty Images hide caption

itoggle caption Doug Pensinger/Getty Images