various Hornbills

Many Hornbills have a disproportionately large "casque" on their horn-shaped bill.

Hornbills have physiological and behavioural differences from other birds. In addition to the casque (on some), they have their first two neck vertebrae fused to support bills, have long eyelashes and different kidneys. In all but the Ground Hornbills, the female bird seals herself in a tree cavity with mud and sticks while incubating and raising young, leaving a small hole for the male to feed them.
The GREAT HORNBILL, Buceros bicornis, also called GREAT INDIAN and GREAT PIED HORNBILL, comes from parts (NW & SE) of India and Southeast Asia. One of the largest tree-dwelling hornbills, its massive yellow and black (hollow) casque is concave on top. Casque colouring differs slightly (black-backed in males and reddish in females) as do eyes (red-brown in males, blue-white in females).
RED-BILLED HORNBILL, Tockus erythrorhynchus, is found in much of sub-Saharan Africa. It is a small hornbill with no casque.
CROWNED HORNBILL, Tockus alboterminatus, from central Africa, has a red bill and a dark body and wings except for a white belly.	TARICTIC HORNBILL, Penelopides panini, comes from the Philippines. The name relates to the call. They have glossy black-green wings and buff fronts (males) or dark fronts (females).	SULAWESI/TEMMINK'S TARICTIC HORNBILL, Penelopides exhartus sanfordi, comes from Indonesia. Shown is a female; the male has a yellow face bordered with white.
(AFRICAN) GREY HORNBILL, Tockus nasutus, has a similar range in sub-Saharan Africa to the Red-billed above but includes Arabia. The female has red on her bill; the male's is all black. The bird is browner and more patterned than the Indian Grey Hornbill.

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Ground Hornbills

Silvery-/Grey-cheeked/Black

Knobbed/Sulawesi Wrinkled

Writhed

Rufous

Von Der Decken's