Galapagos Species Checklist

Gallus gallus domesticus Linnaeus, 1758

Gallina - Gallo, Gallina - Gallo doméstico, Domestic Chicken, domestic fowl

Domestic Chickens in Isabela Island, Galapagos. Photo: Ana Mireya Guerrero, CDF.
Domestic Chickens in Isabela Island, Galapagos. Photo: Ana Mireya Guerrero, CDF.

They are gregarious birds of medium size, capable of performing short flights. They have a distinctive social system and a hierarchical order established: there is a dominant male and a male subjected by all. Females have a separate hierarchy without dominance of males. Sexual dimorphism is evident at plain sight in this genus, the males are larger (50 cm.), they weigh up to 4 kg with two types of caruncular bumps on the head: a crest on the pileus and a pair of lobes which hang on both sides of the beak. The tail is composed of large, arching feathers. Two white spots on the cheeks make the difference between closely related species. It has gray legs, which are fitted with spurs in some races, but this is absent in the females. The hens are smaller, measuring no more than 40 cm and weighing about 2 kg. Its coloration is less striking, the fleshy appendages of the head are smaller, the tail is shorter. Life span depends on race, it could go from five to ten years.

Gallus spp. includes the many forms of domesticated chicken which have been bred and distributed widely across the world as an important food source. In addition to potentially spreading disease to other avian fauna, as generalist feeders, Gallus spp. may also negatively impact upon native flora and fauna.

Taxonomy

Domain
Eukaryota

Kingdom
Animalia

Phylum
Chordata

Class
Aves

Order
Galliformes

Family
Phasianidae

Genus
Gallus

Species
gallus

Subspecies
domesticus

Taxon category: Accepted

Syn: Gallus domesticus

Taxon origin: Introduced - established

Status

Least concern

Ecology

Preference for an altitude zone in Galapagos: Coastal zonera - humid zone

Habitat preferences: They live where they can obtain food and shelter. They occur in agricultural areas, natural forests, planted forests, grasslands, scrub and urban areas. Wild Gallus can be found from coastal areas to high lands in the Galapagos Islands.

Feeding type: Polyphagous

Feeding preferences: Chickens are omnivores. In the wild, they eat a wide variety of vertebrates and invertebrates, as well as plants and seeds. They forage often scraping the ground to locate food such as seeds, insects, even larger animals like lizards, small snakes and young mice. They cannot taste sweet flavors and generally they dislike salty flavors.

Trophic role: Omnivorous

Persistence mechanisms: Gallus gallus is a highly esteemed animal due to the nutritional benefits that currently provides to humans. Nowadays, its reproduction and permanence on the planet is in the hands of humans, who have created an industry of chickens worldwide. There is known to be three chickens (hens or roosters) alive per human being; however, data provided by the FAO in 2010 indicate that humanity consumes about 56 billion chickens and 1.2 billion eggs annually. Therefore, production has to be equal to or greater than this figure.

Reproduction mode: Exclusively sexual

Reproductive biology: G gallus is a social and polygamous animal, males mate with several females throughout the year. Females nest communally, they lay an egg every day for several days (between eight and ten eggs), which are incubated to develop the embryo by rotating it and giving it heat until it is born. During incubation, the embryo is nourished by the yolk, which penetrates through the belly button. Within 21 days the chicken is fully developed and the hatching takes place between 10 and 20 hours. When the chicken hears the chicks, it will cluck to encourage the young to hatch. Mothers are very protective with their offspring; they care for them for 2 weeks before mating again. The eggs do not hatch at the same time, so the mother stays incubating a couple of more days. Between two and four weeks after birth, chicks already have feathers. At eight weeks they already have the adult plumage. Then, the offspring are expelled from the group by their mothers and they form their own group or join another. Males first reach sexual maturity at five months. For artificial incubation, the eggs are transferred to artificial incubators, where the temperature (37 ° C) and relative humidity (55%, raising it to 70% in the past three days to soften the shell) is controlled and the results are satisfactory. The benefit of this method is that thousands of eggs can be incubated at the same time, which benefits the production of chickens for human consumption.

Distribution origin: Is native to Southeast Asia. The national varieties of G. gallus have been widely distributed around the world as a source of food.

Natural enemies: The main predator of Gallus gallus are humans, however both on farms and in the wild, these birds are exposed to the attacks of predators as mustelids, foxes, dogs, wolves, coyotes, raccoons, cats, rats and even birds of prey.

Economic Use: With the Gallus gallus domestication, different races were produced and are used extensively like food source. Either for the meat production or production of eggs, the chicken is one of the animals most exploited on a global scale. Its short development time, quantity and food quality, next to the low cost of production make them much appreciated economically. Annually, they are consumed more than 33 million tons of its muscles, sinews and fat. Approximately 600,000 million eggs are produced per year. The chicken meat can be cooked in many different ways, being a basic element of many restaurants of fast food. The eggs are used extensively in the preparation of a big variety of meals, both sweet and salty. Hens are also used like pet animals due to its docility. Roosters are also trained for fights that are usually very costly and the quantities of money that moves in the bets of fights is very high. The poultry production is an important economic activity in the inhabited islands of the archipelago. The production of chickens and its fattening associated with the growth of the human population and the industry of the tourism are increasing gradually. Its feathers are used for the making of crafts and typical clothes.

Disease vector: Gallus spp., can have a number of diseases that can become harmful to birds, such as Newcastle disease, Mycoplasma gallisepticum, the proventricular parasite Dispharynx sp., Toxoplasma gondii, Salmonella spp, it is even feared that Gallus spp . can be a carrier of H5N1 (bird flu). Antibodies to paramyxovirus, adenovirus, Infectious bursal disease, Avian encephalitis, Reovirus, Infectious bronchitis virus, Infectious laryngotrachitis, Paramyxovirus-1, Mareks, Adenovirus-1 and Mycoplasma gallisepticum was detected in Gallus gallus in the Galapagos Islands, all of these are pathogens of concern for both domestic and wild birds in the Archipelago.

Introduction

Mode of introduction: Intentional

Status in Galapagos: Human dependent

Invasion risk score: Low risk

Impact in Galapagos: Chickens arrived in the Galapagos Islands as a source of food and it is currently the only animal species that is allowed to enter the Islands alive, after fulfilling stringent phytosanitary rules. In the past, without the existence of phytosanitary rules, they entered these poultry to the Islands and with them came a number of diseases. A study on the disease in domestic poultry and wild birds in the Floreana Island, revealed that domestic chickens have 9 diseases, two of which are already present in wild birds. Chickens that are adapted to the wild, also compete with food from other birds, eating invertebrates and seeds. They also prey on small reptiles such as lizards, snakes, and geckos. The impact that the wild chickens may have on populations of invertebrates, plants, and small reptiles has not been studied yet.

Impact elsewhere: Domestic chickens are carriers of many avian diseases (Fowlpox, Newcastle, etc.), and thus they are a pollution risk to native and endemic bird populations in different parts of the world, mainly in Islands. Herbivory and predation of Gallus spp., contribute to the destruction of habitats and they impact plants and native animals. There is little information that extant on the subject. When G. gallus are grouped in large quantities, they become human nuisance due to the noise they produce, mostly by males (roosters). Populations living near airports, are a potential risk to aircrafts, and these can cause considerable damage when there is a collision with an aircraft.

Control History in Galapagos: In the Galapagos Islands there is not and has never been a program of control of roosters, hens or wild chickens. However, municipalities have created regulations regarding the possession of these animals in urban areas, considered a social nuisance.

Control methods elsewhere: When chickens become a social nuisance, they are controlled through manual capture, traps and even with shots, especially if they are suspected of carrying a virus as avian flu virus H5N1, which harm third parties. There is no information on chemical control for G. gallus. The poisoning of chickens is not considered for control due to the high risk of unwanted harmful effects on native avifauna. In Cocos Island, wild chickens are captured using baited traps and then these are distributed among the inhabitants of the island.

Known Pest elsewhere: Introduced and Widespread worldwide

Prevention options: Avoid the transport of these live animals to pristine sites where they do not occur, not only because they could escape and become wild, but to prevent the spread of diseases that can spread and harm native birds.

Distribution

Map of specimen collection localities or observation records for this species in our collections database.

Distribution: Present, in domestic and wild form on the islands Santa Cruz, Isabela, San Cristobal, Floreana and Baltra.

References

  • Wiedenfeld, D.A. (2006) Aves, the Galapagos Islands, Ecuador. Check List 2006 2(2): 1-27.
  • Jiménez-Uzcátegui, G. Carrión, V., Zabala, J., Buitrón, P. & Milstead, B. (2007) Status of introduced vertebrates in Galapagos. Galapagos Report 2006–2007. Charles Darwin Foundation, Puerto Ayora, p. 136–141.
  • Gottdenker, N.L. Walsh, T., Vargas, H., Merkel, J., Jiménez-Uzcátegui, G., J., Miller, R.E., Dailey, M. & Parker, P. (2005) Assessing the risks of introduced chickens and their pathogens to native birds in the Galápagos Archipelago. Biological Conservation 126: 429–439.
  • Thiel, T. Whiteman, N.K., Tirapé, A., Baquero, M. I., Cedeño, V., Walsh, T., Jiménez-Uzcátegui, G. & Parker, P.G. (2005) Characterization of canary pox-like viruses infecting endemic birds in the Galapagos Islands. Journal of Wildlife Diseases 41(2): 342-353.
  • Soos, C. Padilla, L., Iglesias, A., Gottdenker, N., Cruz Bedon, M., Rios, A. & Parker, P.G. (2008) Comparison of pathogens in broiler and backyard chickens on the Galapagos Islands: implications for transmission to wildlife. The Auk 125(2): 445-455.
  • Parker, P.G. Whiteman, N.K., & Miller, R.E. (2006) Conservation medicine on the Galápagos Islands: partnerships among behavioral, population, and veterinarian scientists. The Auk 123(3): 625-638.
  • Dubey, J. P (2009) Toxoplasma gondii Infections in Chickens (Gallus domesticus): Prevalence, Clinical Disease, Diagnosis and Public Health Significance. Zoonoses and Public Health Volume 57 Issue 1, Pages 60 – 73
  • Fassbinder-Orth Carol A. Hofmeister, Erik K.; Weeks-Levy, Carolyn; Karasov, William H (2009) Oral and Parenteral Immunization of Chickens (Gallus gallus) Against West Nile Virus with Recombinant Envelope Protein. Avian Diseases. 53(4). DEC 2009. 502-509
  • Miller, E. Parker P., Duncan M., Merkel J., Padi l la L., Vargas H., Snel l H (2003) Developing an 'Early Warning System' to Monitor Avian Health in the Gallapagos Islands. Verh.ber. Erkrg. Zootiere (2003) 41.
  • Permin, A. G. Pedersen (undated) The need for a holistic view on disease problems in free-range chickens. Network for Smallholder Poultry Development The Royal Veterinary and Agricultural University Frederiksberg, Denmark.
  • Wikelski, M. Foufopoulos, J., Vargas, H., Snell, H. (2004) Galápagos birds and diseases: invasive pathogens as threats for island species. Ecology and Society 9 (5) Available from: http://www.ecologyandsociety.org/vol9/iss1/art5
  • Freire, J.F. Santander, T., Jiménez-Uzcátegui, G., Carrasco, L., Cisneros-Heredia, D., Guevara, E., Sánchez-Nivicela, M., Tinoco, B. (2019) Lista Roja de las aves del Ecuador Quito, Ecuador. 97 pp.

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