Dr. Tom Boyer, veterinarian and reptile specialists, Pet Hospital of Penasquitos, located in San Diego, Calif., fits MC3402, nicknamed Lt. Dan, with prosthesis, May 19. Biologists with NREA discovered two imperiled desert tortoises in late March after they had been attacked by what was presumed to be coyotes. They were found and rescued within a week of each other; one having lost one limb and the other having lost both front limbs. (Photo by James Kever) - Dr. Tom Boyer, veterinarian and reptile specialists, Pet Hospital of Penasquitos, located in San Diego, Calif., fits MC3402, nicknamed Lt. Dan, with prosthesis, May 19. Biologists with NREA discovered two imperiled desert tortoises in late March after they had been attacked by what was presumed to be coyotes. They were found and rescued within a week of each other; one having lost one limb and the other having lost both front limbs. (Photo by James Kever)

Participants of the Park to Park Ride cycle through Joshua Tree National Park, April 29, 2017. The event, hosted by Natural Resources and Environmental Affairs, Joshua Tree National Park and the city of Twentynine Palms, Calif. took riders from Knott’s Sky Park through Joshua Tree National Park to Keys View and back as the final event of Earth Day celebrations in the month of April. (U.S. Marine Corps photo by Cpl. Dave Flores) - Participants of the Park to Park Ride cycle through Joshua Tree National Park, April 29, 2017. The event, hosted by Natural Resources and Environmental Affairs, Joshua Tree National Park and the city of Twentynine Palms, Calif. took riders from Knott’s Sky Park through Joshua Tree National Park to Keys View and back as the final event of Earth Day celebrations in the month of April. (U.S. Marine Corps photo by Cpl. Dave Flores)

The top riders with Natural Resources and Environmental Affairs stand with a trophy for “Get on Your Bike and Ride” month aboard Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., Nov. 17, 2016. NREA took first place aboard the installation for total miles logged during the 29-day event. (Official Marine Corps photo by Cpl. Levi Schultz/Released) - The top riders with Natural Resources and Environmental Affairs stand with a trophy for “Get on Your Bike and Ride” month aboard Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., Nov. 17, 2016. NREA took first place aboard the installation for total miles logged during the 29-day event. (Official Marine Corps photo by Cpl. Levi Schultz/Released)