Pitohui
Encyclopedia
The pitohuis are a genus of birds endemic
to New Guinea
, belonging to the family Pachycephalidae
.
Currently six species
are classified in the genus, though current molecular genetics
research suggests that significant reclassification of the Pachycephalidae may be needed.
Pitohuis are brightly coloured, omnivorous birds. The skin and feathers of some pitohuis, especially the Variable and Hooded Pitohuis, contain powerful neurotoxic
alkaloid
s of the batrachotoxin
group (also secreted by the Colombia
n poison dart frog
s, genus Phyllobates). It is believed that these serve the birds as a chemical defence, either against ectoparasites or against visually guided predators such as snake
s, raptor
s or humans. (Dumbacher, et al., 1992) The birds probably do not produce batrachotoxin themselves. It is most likely that the toxins come from the Choresine genus of beetles, part of the bird's diet.http://www.calacademy.org/science_now/academy_research/powerful_poison.html (Dumbacher, et al., 2004). Due to their toxicity, Papua New Guineans call the pitohuis rubbish birds as they are not good for eating; however in desperate times they can be consumed but only after the feathers and skin are removed and the flesh is coated in charcoal and then roasted. (Piper, 2007)
The Hooded Pitohui is brightly coloured, with a brick red belly and a jet black head. The Variable Pitohui, as its name implies, exists in many different forms, and twenty subspecies with different plumage patterns have been named. Two of them, however, closely resemble the Hooded Pitohui.
It has been suggested that the birds' bright colours are an example of aposematism
(warning colouration), and the similarity of the Hooded Pitohui and some forms of the Variable Pitohui might then be an example of Müllerian mimicry
, in which dangerous species gain a mutual advantage by sharing colouration, so that an encounter with either species trains a predator to avoid both. (Dumbacher & Fleischer, 2001)
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, belonging to the family Pachycephalidae
Pachycephalidae
The family Pachycephalidae, collectively the whistlers, includes the whistlers, shrike-thrushes, shrike-tits, pitohuis and Crested Bellbird, and is part of the ancient Australo-Papuan radiation of songbirds. Its members range from small to medium in size, and occupy most of Australasia...
.
Currently six species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are classified in the genus, though current molecular genetics
Molecular genetics
Molecular genetics is the field of biology and genetics that studies the structure and function of genes at a molecular level. The field studies how the genes are transferred from generation to generation. Molecular genetics employs the methods of genetics and molecular biology...
research suggests that significant reclassification of the Pachycephalidae may be needed.
Species
- Variable PitohuiVariable PitohuiThe Variable Pitohui is a species of bird in the Colluricinclidae family.It is found in Indonesia and Papua New Guinea....
, Pitohui kirhocephalus - Hooded PitohuiHooded PitohuiThe Hooded Pitohui, Pitohui dichrous is a songbird of New Guinea with black and orange plumage.This species and its two close relatives, the Variable Pitohui and the Brown Pitohui, were the first documented poisonous birds...
, Pitohui dichrous - White-bellied PitohuiWhite-bellied PitohuiThe White-bellied Pitohui is a species of bird in the Colluricinclidae family.It is found in Indonesia and Papua New Guinea....
, Pitohui incertus - Rusty PitohuiRusty PitohuiThe Rusty Pitohui, Pitohui ferrugineus is a medium-sized, approximately 28cm long, rusty brown songbird with a strong black bill, pale iris and yellowish-buff below. It is the largest member of its family. Both sexes are similar....
, Pitohui ferrugineus - Crested PitohuiCrested PitohuiThe Crested Pitohui is a species of bird in the Colluricinclidae family.It is found in Indonesia and Papua New Guinea.Its natural habitat is subtropical or tropical moist lowland forests.-References:...
, Pitohui cristatus - Black PitohuiBlack PitohuiThe Black Pitohui is a species of bird in the Colluricinclidae family.It is found in Indonesia and Papua New Guinea.Its natural habitat is subtropical or tropical moist lowland forests.-References:...
, Pitohui nigrescens
Pitohuis are brightly coloured, omnivorous birds. The skin and feathers of some pitohuis, especially the Variable and Hooded Pitohuis, contain powerful neurotoxic
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...
alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
s of the batrachotoxin
Batrachotoxin
Batrachotoxins are extremely potent cardiotoxic and neurotoxic steroidal alkaloids found in certain species of frogs , melyrid beetles, and birds...
group (also secreted by the Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
n poison dart frog
Poison dart frog
Poison dart frog is the common name of a group of frogs in the family Dendrobatidae which are native to Central and South America. These species are diurnal and often have brightly-colored bodies...
s, genus Phyllobates). It is believed that these serve the birds as a chemical defence, either against ectoparasites or against visually guided predators such as snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s, raptor
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
s or humans. (Dumbacher, et al., 1992) The birds probably do not produce batrachotoxin themselves. It is most likely that the toxins come from the Choresine genus of beetles, part of the bird's diet.http://www.calacademy.org/science_now/academy_research/powerful_poison.html (Dumbacher, et al., 2004). Due to their toxicity, Papua New Guineans call the pitohuis rubbish birds as they are not good for eating; however in desperate times they can be consumed but only after the feathers and skin are removed and the flesh is coated in charcoal and then roasted. (Piper, 2007)
The Hooded Pitohui is brightly coloured, with a brick red belly and a jet black head. The Variable Pitohui, as its name implies, exists in many different forms, and twenty subspecies with different plumage patterns have been named. Two of them, however, closely resemble the Hooded Pitohui.
It has been suggested that the birds' bright colours are an example of aposematism
Aposematism
Aposematism , perhaps most commonly known in the context of warning colouration, describes a family of antipredator adaptations where a warning signal is associated with the unprofitability of a prey item to potential predators...
(warning colouration), and the similarity of the Hooded Pitohui and some forms of the Variable Pitohui might then be an example of Müllerian mimicry
Müllerian mimicry
Müllerian mimicry is a natural phenomenon when two or more harmful species, that may or may not be closely related and share one or more common predators, have come to mimic each other's warning signals...
, in which dangerous species gain a mutual advantage by sharing colouration, so that an encounter with either species trains a predator to avoid both. (Dumbacher & Fleischer, 2001)