Bucerotidae

2

Writhed Hornbill (Aceros leucocephalus)

Also known as the Mindanao Wrinkled Hornbill, the writhed hornbill is a species of hornbill that is endemic to the Philippine islands of MIndanago, Dinagat and Camigiun Sur. They typically inhabit humid forests and will feed on fruits, insects and small vertebrates. Like most hornbills A.leucocephalus is sexually dimorphic with males sporting a rufous colored head and neck. However, both sexes have bright red bills/casques and black bodies.

The writhed hornbill is currently listed as near threatened and faces threats from habitat loss and hunting.

Classification

Animalia-Chordata-Aves-Coraciiformes-Bucerotidae-Aceos-A. leucocephalus

Image(s): Olaf Oliviero Riemer

White-crowned Hornbill - Berenicornis comatus

This striking birds is a White-crowned Hornbill, Berenicornis comatus (Bucerotiformes - Bucerotidae), a Near Threatened species confined to southern Myanmar, southern Thailand, Peninsular Malaysia, Sumatra and Borneo. A population has also recently been discovered in Cambodia.

The most noticeable feature of this fantastically bizarre looking bird is its white crown feathers which erect in a spiky crest. The white-crowned hornbill also possesses an ornamental casque on top if its bill, characteristic of many hornbills.

The White-crowned Hornbill is generally uncommon, but possibly overlooked owing to its unobtrusive habits (that remains beneath the forest canopy, and so is most often heard), only sighted when flying across gaps in the forest in small groups.

References: [1] - [2] - [3]

Photo credit: ©Massimo Greco | Locality: captive, Phuket Zoo, Thailand (2006)

Made with Flickr

Sri Lanka Grey Hornbill (Ocyceros gingalensis)

…a species of hornbill (Bucerotidae) which is a widespread and common endemic resident breeder in Sri Lanka. Sri Lanka grey hornbills are gregarious birds, found mostly in forested habitats. They are known to feed mostly on figs, berries, and other fruit like other hornbills but  will also occasionally take small rodents, reptiles, and insects. 

Classification

Animalia-Chordata-Aves-Bucerotiformes-Bucerotidae-Ocyceros-O. gingalensis

Image: Gihan Jayaweera

2

Does the large bill of the hornbills is a hindrance in their visual field?

Well, to a large extent, yes, but it also has its advantages related to precision-grasping and sunshades. 

Interspecific comparisons of the topography of avian visual fields have indicated that the extent and position of the frontal binocular field is related to the degree to which vision is employed to control the position of the bill or feet when they are used to take food items.

A study on visual field topography in Tockus leucomelas (Bucerotidae), the Southern Yellow-billed Hornbill, has shown that bill indeed intrudes into the binocular field. This intrusion of the bill restricts the width of the binocular field but allows the birds to view their own bill tips. It is suggested that this is associated with the precision-grasping feeding technique of hornbills. 

When feeding, hornbills employ ‘precision-grasping’. The bill is used as a pair of forceps, grasping an item between the tips and then tossing it back into the throat or further back into the mouth. Items are often manipulated in the bill tips.

Interspecific comparison shows that eye size and the width of the blind area above the head are significantly correlated. The limit of the upper visual field in hornbills is viewed through the long lash-like feathers of the upper lids and these appear to be used as a sunshade mechanism. 

Reference: [1]

Photo credit: [Top: ©Stephan Tuengler | Locality: Kalahari Desert, Africa] - [Bottom: ©Ian White | Locality: Modipane, Kgatleng, Botswana]

Made with Flickr

Silvery-cheeked Hornbill | ©fishead2000 

Scientific Illustration - Watercolor and pen.

The Silvery-chekked Hornbill is an African birds scientifically named Bycanistes brevis (Coraciiformes - Bucerotidae).

Made with Flickr

Malabar Pied Hornbills

This astounding picture of a pair of Malabar Pied Hornbills, Anthracoceros coronatus (Coraciiformes - Bucerotidae) was shot by wildlife photographer Sachin Rai.

Sachin spotted the duo late one evening in Dandeli, Karnataka, India, where flocks of hornbills are known to congregate to feed, copulate and roost in the trees before dusk descends.

Flying close to each other, the two birds - evidently of the same sex - suddenly turned and locked beaks mid-air, the spectacular show lasting for less than a second when this image was captured!

Though not much is known about this behavior, it is thought that these two birds are locked in an act of pre-roosting behavior. In scientific literature, this behaviour is known as casque-butting, believed to be a form of dominance display or playful chase or a pre-breeding interaction between adults birds. Also reported in other species like the great pied hornbill, such behaviour only adds to the fascination of these already enchanting birds.

This image won Sachin Rai the Sanctuary Asia - ABN Amro Award.

Red-billed Hornbill
Tockus erythrorhynchus
/ Photo by J.I.Padilha 2011

Tude e João

¤

Calao à bec rouge -Northern red-billed hornbill - Toco piquirrojo - アカハシコサイチョウ - Calau-de-bico-vermelho - Rotschnabeltoko - (Tockus erythrorhynchus).