The mud crowd
The first teasing rain showers had fallen, but the rivers were still only small mud pools. Mark was watching the jostling hippos when a Nile crocodile surprised the group. As the nearest one retreated, a ripple of panic swept through the crowd. Keeping near his vehicle, Mark framed the commotion.
Hippos rest in schools of up to 150 individuals during the day and mud is as good as water to keep their skin moist. The cold-blooded crocodile needs this muddy external heat sink to stay cool in hot conditions. As an apex predator, it seems relaxed around the hippos, but together, they would be more than a match for it, if necessary.
Nikon D810; 70–200mm f2.8 lens at 86mm; 1/500 sec at f8; ISO 640.
Ikuu River, Katavi National Park, Tanzania
Sign up to receive emails from the Natural History Museum about events and exhibitions, including Wildlife Photographer of the Year.
Love this image?
Choose your favourite from this year's collection. You can only choose once.
Mark Cale, UK
After leaving school, Mark worked as a photography assistant to John Rawings and Norman Parkinson. He has always loved photography and video games and in 1982 he set up a games label. The digital camera revolution and the birth of his daughter brought back his passion for photography, and he now travels the world shooting images for use in his games.