John Chan / Great horned owl (Bubo virginianus) chicks stretching and flapping their wings, Southern California, USA, May.

John Chan / Great horned owl (Bubo virginianus) chick watching for parents to return with food, Southern California, USA, June.

Daniel Heuclin / Horned viper (Vipera ammodytes) in natural setting, Turkey.

John Cancalosi / Great horned owl (Bubo virginianus) chick stretching its wings in nest in a Saguaro (Carnegiea gigantea), is groomed by its parent, Sonoran Desert, Arizona, USA, May.

Marie Read / Horned Puffin (Fratercula corniculata) flying over a pattern of kelp and sea foam, photographed from above, St. Paul, Pribilof Islands, Alaska, USA. July.

Alan Murphy/ BIA / Great Horned Owl (Bubo virginianus), Texas

Robert Valentic / Phuket horned tree lizard (Acanthosaura phuketensis) near Bang Pae Waterfall, Khao Phra Thaew NP, Phuket Island, Thailand.

Piotr Naskrecki / Longhorn Beetle (Tithoes confinis) on hand, Gorongosa National Park, Mozambique

Chien Lee / Kobayashi's Horned Frog (Megophrys kobayashii), Kinabalu National Park, Sabah, Malaysia

Murray Cooper / Horned Screamer (Anhima cornuta), South America

Chien Lee / Amazon Horned Frog (Ceratophrys cornuta), Yasuni National Park, Ecuador

Chien Lee / Amazon Horned Frog (Ceratophrys cornuta) camouflaged in leaf litter, Yasuni National Park, Ecuador