Staffan Widstrand / Wild Wonders of China / Great pied hornbill (Buceros bicornis) male bird photographed in flight in Hong Bung He, Dehong, Yunnan, China

Neil Aldridge / Southern ground hornbill (Bucorvus leadbeateri) juvenile with an adult bird close by on the Selinda Reserve in northern Botswana. Vulnerable.

Bence Mate / Hoopoe ( Upupa epops) in flight with blurred wings, Kiskunsagi National Park, Pusztaszer, Hungary. May.

Bence Mate / Hoopoe (Upupa epops) landing, with lizard prey, Kiskunsagi National Park, Pusztaszer, Hungary. May.

Bence Mate / Hoopoe (Upupa epops) courtship feeding, Pusztaszer, Hungary, May.

Neil Aldridge / Southern yellow-billed hornbill (Tockus leucomelas) displays while calling in winter, Kruger National Park, South Africa.

David Tipling / Huli Wigmen from the Tari Valley in Southern Highlands of Papua New Guinea, wearing a bill from Blyth's Hornbill as decoration, August 2011

Hermann Brehm / Hoopoe (Upupa epops) perched on branch with cricket prey, Hungary. June

Oscar Dewhurst / Malabar pied hornbill (Anthracoceros coronatus) male in flight. Goa, India. September.

Hanne & Jens Eriksen / Eurasian hoopoe (Upupa epops) raising crown and stretching wings and tail. Oman, March.

Ann & Steve Toon / Common scimitarbill (Rhinopomastus cyanomelas), Kgalagadi transfrontier park, South Africa

Ann & Steve Toon / Common scimitarbill (Rhinopomastus cyanomelas) on tree trunk, Kgalagadi transfrontier park, South Africa.