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.

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

Daniel Heuclin / Traditional bush hunter with a calao / Hornbill head decoration, preparing bow and arrow for hunt, Northern Cameroon, West Africa. No release available.

Tim Laman / Great indian hornbill (Buceros bicornis) male brings food to nest, Khao Yai National Park, Thailand

John Waters / Southern Yellow billed Hornbill {Tockus leucomelas} Kalahari Desert, Northern Cape, South Africa

Karl Ammann / Ground hornbill {Bucorvus leadbeateri} with frog prey in beak, Kenya

Andrew Parkinson / Yellow billed hornbill {Tockus flavirostris} Etosha NP, Namibia

Staffan Widstrand / Southern Yellow-billed Hornbill, (Tockus leucomelas) tossing a fly larva at a carrion site, Zimanga Private Nature Reserve, KwaZulu Natal, South Africa

Staffan Widstrand / Southern Yellow-billed Hornbill, (Tockus leucomelas), eating fly larvae at a carrion site, Zimanga Private Nature Reserve, KwaZulu Natal, South Africa

Sandesh Kadur / Great Indian Hornbill (Buceros bicornis) flying in forest habitat, Tamil Nadu, Western Ghats, India

Sandesh Kadur / Great Indian Hornbill (Buceros bicornis) male in forest habitat, Tamil Nadu, Western Ghats, India