The horned guan (''Oreophasis derbianus'') is an

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

species in an ancient group of

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s of the family

Cracidae The chachalacas, guans, and curassows are birds in the Family (biology), family Cracidae. These are species of tropical and subtropical Central America, Central and South America. The range of one species, the plain chachalaca, just reaches south ...

, which are related to the

Australasia Australasia is a subregion of Oceania, comprising Australia, New Zealand (overlapping with Polynesia), and sometimes including New Guinea and surrounding islands (overlapping with Melanesia). The term is used in a number of different context ...

megapode The megapodes, also known as incubator birds or mound-builders, are stocky, medium-large, chicken-like birds with small heads and large feet in the family Megapodiidae. Their name literally means "large foot" and is a reference to the heavy leg ...

s or mound builders (Megapodiidae). It is found in Mexico, Guatemala, and possibly Honduras.

Taxonomy and systematics

The horned guan is not closely related to other guans, but merely resembles these birds in overall shape and color, whereas the horn is more reminiscent of the

helmeted curassow The helmeted curassow (''Pauxi pauxi'') or northern helmeted curassow, is a large terrestrial bird in the family Cracidae found in the subtropical cloud-forest in steep, mountainous regions of western Venezuela and northern Colombia. There are t ...

s. The

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

is the only survivor of a very ancient lineage of cracids that has been

evolving Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certai ...

independently from all other living members of this

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

for at least 20 million years, and possibly as much as 40 million years. Given that the basal relationships of the living cracids are not well resolved, the horned guan is often placed in its own

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Oreophasinae. Other taxonomists have placed it in either subfamily Cracinae or Penelopinae.Eo Soo Hyung, Bininda-Emonds, O.R.P., and Carroll, J.P. (2009). A phylogenetic supertree of the fowls (Galloanserae, Aves). Zool. Scripta. 38(5): 465–481.del Hoyo, J. and G. M. Kirwan (2020). Horned Guan (''Oreophasis derbianus''), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.horgua1.01 retrieved April 7, 2024 The

holotype specimen A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was Species description, formally described. It is either the single such physical example (or illus ...

of the horned guan is held in the collections of

National Museums Liverpool National Museums Liverpool, formerly National Museums and Galleries on Merseyside, comprises several museums and art galleries in and around Liverpool in Merseyside, England. All the museums and galleries in the group have free admission. The mu ...

World Museum World Museum is a large museum in Liverpool, England which has extensive collections covering archaeology, ethnology and the natural and physical sciences. Special attractions include the Natural History Centre and a planetarium. Entry to the ...

, with accession number NML-VZ D210. The specimen was collected from

Volcán de Fuego Volcán de Fuego (; Spanish for "Volcano of Fire", often shortened to Fuego) or Chi Q'aq' ( Kaqchikel for "where the fire is") is an active stratovolcano in Guatemala, on the borders of Chimaltenango, Escuintla and Sacatepéquez departments. ...

, Guatemala by Don Joaquin Quinones circa 1843 and came to the Liverpool national collection via the

13th Earl of Derby Edward Smith-Stanley, 13th Earl of Derby (21 April 1775 – 30 June 1851), styled Lord Stanley from 1776 to 1832, and Baron Stanley of Bickerstaffe from 1832–4, was an English politician, peer, landowner, builder, farmer, art collector and na ...

’s collection which was bequeathed to the people of Liverpool. The horned guan is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

Description

The horned guan is long. Its most distinctive feature is the tall, red, fleshy "horn" on its forehead. It has a small head, long strong legs, and a long broad tail. The sexes are alike in plumage but males have a taller horn and longer wings, tail, and legs than females. Adults have a glossy black head, neck, and upperparts with a bluish sheen. Their tail is black with a wide white band near its base. Their throat, breast, and upper belly are whitish with black flecks and their lower belly and flanks are brown. They have a small red

dewlap A dewlap is a longitudinal flap of skin or similar flesh that hangs beneath the lower jaw or neck of many vertebrates. More loosely, it can be various similar structures in the neck area, such as those caused by a double chin or the submandibula ...

, a white iris, a yellow bill, and red legs and feet. Juveniles resemble adults but are duller and have a smaller horn.

Distribution and habitat

The horned guan is found in the southern Mexican state of

Chiapas Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the Political divisions of Mexico, 32 federal entities of Mexico. It comprises Municipalities of Chiapas, 124 municipalities and its capital and large ...

, possibly in

Oaxaca Oaxaca, officially the Free and Sovereign State of Oaxaca, is one of the 32 states that compose the political divisions of Mexico, Federative Entities of the Mexico, United Mexican States. It is divided into municipalities of Oaxaca, 570 munici ...

, and in southern Guatemala. Reports from Honduras have not been confirmed. Its distribution is not continuous but highly local. It inhabits humid subtropical

montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

evergreen forest An evergreen forest is a forest made up of evergreen trees. They occur across a wide range of climatic zones, and include trees such as conifers and holly in cold climates, eucalyptus, live oak, acacias, magnolia, and banksia in more temperate zo ...

cloudforest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, ...

, and pine-oak forest. Its habitat is characterized by much undergrowth of tree ferns,

epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

s, mosses, and vines. In elevation it mostly ranges between but locally occurs as low as and as high as .del Hoyo, J., and A. Motis (2004). Update chapter. In Curassows and Related Birds (J. Delacour, and D. Amadon), Second edition. Lynx Edicions, Barcelona, Spain, and American Museum of Natural History, New York, USA. pp. 322–476.

Behavior

Movement

The horned guan is a year-round resident throughout its range.

Feeding

The horned guan feeds mostly on a very wide variety of fruits; green leaves are a significant part of its diet with flowers and possibly insects eaten in small amounts. It forages singly or in small groups at all levels of the forest including the ground. Many seeds pass intact through its system, which suggests that it might be a significant dispersal agent.González-García, F., Santana-C., E., Jordano Barbudo, P.D., Rico-Gray, V. and Urios Moliner, V. (2017). Diet and feeding behavior of the Horned Guan (''Oreophasis derbianus'') in Mexico. Wilson J. Orn.. 129(4): 771–782.

Breeding

Most of the information about the horned guan's breeding biology comes from Mexico in a study published in 1995. Its breeding season appears to span at least from January to March. It is believed to be

polygynous Polygyny () is a form of polygamy entailing the marriage of a man to several women. The term polygyny is from Neoclassical Greek πολυγυνία (); . Incidence Polygyny is more widespread in Africa than in any other continent. Some scholar ...

, with males spending a few days with each of three to five females. Its nest is an oval structure of dry leaves and roots place high in a tree and usually near running water. The clutch size is two eggs. The female incubates the clutch for 34 to 36 days and chicks leave the nest about three to six days after hatch.

Vocalization

Male and female horned guans have very different vocalizations. Males have a repertoire of at least five calls and females have seven or eight. Female's calls are "guttural and louder compared to those of males". The male's main call is "a very deep, slow and soft 'mooing'...comprising seven notes, a single brief hum followed by six paired hums, i.e. 'hum; hum, hummm; hum, hummm; hum, hummmmm' " that can be repeated for an hour. Females usually call in response to males, with a "guurk, guurk, guurk,... or guauuu, guauuu, guauuu". Oreophasis_Gray

Status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

originally in 1988 assessed the horned guan as Threatened, then in 1994 as Vulnerable, and since 2000 as Endangered. It has a very limited range and its estimated population of 600 to 1700 mature individuals is believed to be decreasing. Its range has contracted due to logging, firewood gathering, conversion of forest to agriculture, and subsistence hunting pressure. "The isolation of disjunct subpopulations makes this species especially vulnerable to further local extirpation. Climate change is further expected to exacerbate horned guan population declines by inducing shifts in the species' already restricted range". It does occur in at least one protected area in each of Mexico and Guatemala. However, one of its largest populations is on the unprotected

Volcán Tacaná The volcano Tacaná is the second highest peak in Central America at , located in the Sierra Madre de Chiapas of western Guatemala and southern Mexico. It is also known in Mexico as ''Volcán Tacina''. Geography The volcano is located within t ...

on the border between the two countries.

References

External links

BirdLife species factsheet
Aventuras Naturales
Horned Guan image
(Oil paintings)

VIREO {{Taxonbar, from1=Q147327, from2=Q1089307

horned guan The horned guan (''Oreophasis derbianus'') is an endangered species in an ancient group of birds of the family Cracidae, which are related to the Australasian megapodes or mound builders (Megapodiidae). It is found in Mexico, Guatemala, and pos ...

Birds of Guatemala Birds of Mexico

Central American montane forests