Buceros hydrocorax Linnaeus, 1766

Taxonomy and Naming

Buceros hydrocorax, first described by Linnaeus in 1766, is a large hornbill bird endemic to the Philippines.

General Distribution

It inhabits primary, mature secondary, and disturbed forests, and occurs across most of the country, with the exception of the Mimaropa, Sulu, and Western Visayas regions.

Body Coloration

This species has a dark body, with rufous legs, chest, and neck, an off-white tail, a black face, and a yellow throat.

Bill Coloration

The nominate subspecies has an entirely red bill, while the subspecies semigaleatus and mindanensis have pale yellow coloring on the distal half of the bill.

Sexual Dimorphism

Buceros hydrocorax is sexually dimorphic: females have striking electric blue eyes, a smaller casque, and no eye ring, while males have yellow eyes and a larger casque.

Bill Pigmentation Source

The species' characteristic red bill color comes from the oxidation of oils produced by the uropygial gland.

Habitat Types

This species occurs mainly in primary evergreen dipterocarp forests, but also uses secondary forest habitat.

Elevational Range

The northern form of this rufous hornbill has been recorded at elevations up to 760 meters on Luzon, while the southern form has been recorded up to 2,100 meters above sea level on Mt. Apo.

Global Conservation Status

The species as a whole is classified as Vulnerable.

National Conservation Status

The northern rufous hornbill is considered more threatened: it is classified as Endangered on the Philippines' National List of Threatened Terrestrial Fauna, while the southern species or subspecies is classified as Vulnerable.

Primary Threats

This species faces substantial hunting pressure and widespread habitat loss caused by logging and conversion of land to agriculture.

Ongoing Population Pressures

Ongoing subsistence hunting and felling of remaining dipterocarp forests for agriculture are thought to further reduce population numbers.

Habitat Fragmentation

The species' current range is highly fragmented, and likely suffers from an acute shortage of suitable nesting trees in at least parts of its range.

Hunting Impacts

Hunters climb nesting trees to capture adult females and their chicks for the illegal wildlife trade, and hunting for sport and food has been recorded across the species' entire range.

Northern Form Protected Areas

Northern rufous hornbills occur in a small number of protected areas, including Quezon Protected Landscape, Bataan National Park, Northern Sierra Madre Natural Park, Aurora Memorial National Park, and Kalbario–Patapat Natural Park.

Southern Form Protected Areas

Southern rufous hornbills occur in Samar Island Natural Park, Mount Apo, and Pasonanca Natural Park.

Protected Area Enforcement Gaps

Despite being present in numerous protected areas, there is lax actual protection from illegal logging, hunting, and capture for the wildlife trade.

Documented Hunting Incident

In 2014 in Adams, Ilocos Norte, the son of a Vice-Mayor was photographed carrying a deceased juvenile Buceros hydrocorax he had just shot.

Local Extinction Record

The species is now locally extinct at Mt. Palay-palay in Cavite, due to hunting and the construction of roads and the Kaybiang Tunnel.

Common Name Etymology

In behaviour and ecology, this species is sometimes called "the clock of the mountains" because of its periodic noontime call, which can be heard up to 1.5 kilometers away.

Flight Characteristics

Its large size means its wings produce a distinct whirring sound during flight.

Predation Record

It has been recorded as prey of the Philippine eagle.

Flocking Behavior

It can be seen in flocks of up to 12 birds, and the southern rufous hornbill is occasionally found in mixed flocks with Writhed hornbills that can reach up to 20 individuals total.