Toxic bird

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The hooded pitohui. A neurotoxin called homobatrachotoxin found in the birds' skin and feathers causes numbness and tingling in those touching the bird. Hooded Pitohui.jpg
The hooded pitohui. A neurotoxin called homobatrachotoxin found in the birds' skin and feathers causes numbness and tingling in those touching the bird.

Toxic birds are birds that use toxins to defend themselves from predators. No species of bird is known to actively inject or produce venom, but the discovered toxic birds are known to be poisonous to touch and eat. These birds usually sequester poison from animals and plants they feed on, especially poisonous insects. Birds with known toxic traits include the pitohui and ifrita birds from Papua New Guinea, the European quail, the spur-winged goose, hoopoes, the bronzewing pigeon, and the red warbler, among others. [1]


The pitohui, the ifrita, and the rufous or little shrikethrush all sequester batrachotoxin in their skin and feathers. [2] The African spur-winged goose is toxic to eat as it sequesters poison in its tissues, from the blister beetles that it feeds on. [3] European quail are also known to be toxic and are able to cause coturnism at certain stages in their migrations.

Initial research

The first research done on toxic birds was published in 1992 by Dumbacher et al., [4] which found traces of the neurotoxin homobatrachotoxin, a steroid alkaloid with the ability to polarize Na+ channels, in the feathers and body tissue of many species of New Guinea passerine birds of the genus Pitohui and Ifrita. [5] Before 1992, the toxins of the passerine birds of New Guinea had only been found in three species of poison dart frogs in Western Colombia (Phyllobates terribilis, Phyllobates bicolor, Phyllobates aurotaenia). Phyllobates kept in captivity do not develop the toxins, and the extent of the toxicity varies both in the pitohuis across their range. Both of these facts suggest that the toxins are obtained from diet. Toxic insects, primarily beetles, in the diets of these toxic birds are the most common sources for the bird’s toxicity. In the New Guinea bird species of Pitohui and Ifrita, the beetles of genus Choresine , natively known as nanisani, are pivotal food sources, and toxin sources, of these birds. [6]

Use of toxins

Poison is the only form of toxic weaponry that has evolved within birds, and it appears to have been gained in particular independent clusters of avian lineages (e.g., Pitohui and Ifrita). These clusters appear near the tips of the phylogeny which, combined with the higher rate of loss than gain, suggests that many lineages have likely evolved the ability to sequester poisons through time, but have subsequently lost that ability. [7] It is hypothesized that this chemical defence is effectively used against predators such as snakes, raptors, and some arboreal marsupials. It is also hypothesized that skin/feather toxicity is used as a defence against ectoparasites. Batrachotoxins have been found to be poisonous to distantly related orders of insects, which suggests that batrachotoxins may well be effective against a wide range of ectoparasite arthropods.

These ectoparasites have been found to play a role in the reproduction of birds in the genus Pitohui and Ifrita, in which their presence on the host increases time and energy spent during reproduction periods. The development of batrachotoxin in toxic birds has led to an advantage of these birds against ectoparasites, as they deter parasites from finding sanctuary on bird body tissue and feathers with the toxin, which suggests ectoparasites to be an important evolutionary force in sexual selection. [8]

Origins of batrachotoxins in birds

The search for batrachotoxins in organisms consumed by birds has yet to indicate an exogenous source. Stomach content studies reveal a variety of arthropods, mostly insects, and occasional fruits, but chemical analyses of these materials fail to reveal the presence of toxins. One can only speculate on sources of avian batrachotoxins if they are not synthesized de novo . The occurrence of batrachotoxins in muscle, viscera, and deep regions of the skin argues against these substances being topically applied, i.e., through “anting,” a behavior common in passerines where arthropods, fruits, or other materials are smeared directly onto the plumage. Perhaps birds sequester batrachotoxins produced by microorganisms in a way analogous to that in which pufferfish may obtain tetrodotoxin, another neurotoxin, from bacteria in their skin. [9]

See also

Related Research Articles

<span class="mw-page-title-main">Pitohui</span>

The pitohuis are bird species endemic to New Guinea. The onomatopoeic name is thought to be derived from that used by New Guineans from nearby Dorey (Manokwari), but it is also used as the name of a genus Pitohui which was established by the French naturalist René Lesson in 1831. The unitalicized common name however refers to perching birds that belong to several genera of multiple bird families. The genera include Ornorectes, Melanorectes, and Pseudorectes apart from Pitohui.

<span class="mw-page-title-main">Hooded pitohui</span> Consumption of feces

The hooded pitohui is a species of bird in the genus Pitohui found in New Guinea. It was long thought to be a whistler (Pachycephalidae) but is now known to be in the Old World oriole family (Oriolidae). Within the oriole family, this species is most closely related to the variable pitohuis in the genus Pitohui, and then the figbirds.

<span class="mw-page-title-main">Poison dart frog</span> Family of amphibians

Poison dart frog is the common name of a group of frogs in the family Dendrobatidae which are native to tropical Central and South America. These species are diurnal and often have brightly colored bodies. This bright coloration is correlated with the toxicity of the species, making them aposematic. Some species of the family Dendrobatidae exhibit extremely bright coloration along with high toxicity, while others have cryptic coloration with minimal to no amount of observed toxicity. The species that have great toxicity derive this feature from their diet of ants, mites and termites. However, other species that exhibit cryptic coloration, and low to no amounts of toxicity, eat a much larger variety of prey. Many species of this family are threatened due to human infrastructure encroaching on their habitats.

<span class="mw-page-title-main">Batrachotoxin</span> Chemical compound

Batrachotoxin (BTX) is an extremely potent cardio- and neurotoxic steroidal alkaloid found in certain species of beetles, birds, and frogs. The name is from the Greek word βάτραχος, bátrachos, 'frog'. Structurally-related chemical compounds are often referred to collectively as batrachotoxins. In certain frogs, this alkaloid is present mostly on the skin. Such frogs are among those used for poisoning darts. Batrachotoxin binds to and irreversibly opens the sodium channels of nerve cells and prevents them from closing, resulting in paralysis and death. No antidote is known.

<span class="mw-page-title-main">Venomous mammal</span> Venom-producing animals of the class Mammalia

Venomous mammals are animals of the class Mammalia that produce venom, which they use to kill or disable prey, to defend themselves from predators or conspecifics or in agonistic encounters. Mammalian venoms form a heterogeneous group with different compositions and modes of action, from three orders of mammals: Eulipotyphla, Monotremata, and Chiroptera. It has been proposed that some members of a fourth order, Primates, are venomous. To explain the rarity of venom delivery in Mammalia, Mark Dufton of the University of Strathclyde has suggested that modern mammalian predators do not need venom because they are able to kill quickly with their teeth or claws, whereas venom, no matter how sophisticated, requires time to disable prey.

<span class="mw-page-title-main">Golden poison frog</span> Species of amphibian

The golden poison frog, also known as the golden dart frog or golden poison arrow frog, is a poison dart frog endemic to the rainforests of Colombia. The golden poison frog has become endangered due to habitat destruction within its naturally limited range. Despite its small size, this frog is likely the most poisonous animal on the planet.

<i>Phyllobates bicolor</i>

Phyllobates bicolor, or more commonly referred to as the Black-legged poison dart frog, is the world's second-most toxic dart frog. Under the genus Phyllobates, this organism is often mistaken as Phyllobates terribilis, the golden poison frog, as both are morphologically similar. However, Phyllobatesbicolor is identifiable by the yellow or orange body and black or dark blue forelimbs and hindlegs, hence the name black-legged dart frog. Phyllobates bicolor are commonly found in tropical forests of the Chocó region of Colombia. The diurnal frogs live along the rainforest ground near streams or puddles that form. Notably, P. bicolor is a member of the family Dendrobatidae, or poison dart frog. P. bicolor, along with the rest of the Phyllobates species, produce a neurotoxin known as a batrachotoxin that inhibits specific transmembrane channels in cells. Due to this highly deadly toxin that the frogs secrete, many indigenous groups of the Colombian rainforest have extracted the toxins to create poison tipped darts used for hunting. During the breeding period, P. bicolor emits high pitched single notes as a mating call. As in all poison dart frogs, it is common for the father of tadpoles to carry the offspring on his back until they reach a suitable location for the tadpoles to develop. P. bicolor is an endangered species according to the IUCN red list. Currently, deforestation, habitat loss, and pollution pose the biggest threat to the species. Limited conservation efforts have been attempted to prevent further damage to the species. Despite this, there are still institutions such as the Baltimore National Aquarium in Baltimore, Maryland and the Tatamá National Natural Park in Colombia that are engaged in P. bicolor conservation efforts such as captive breeding.

<span class="mw-page-title-main">Blue-capped ifrit</span> Species of bird

The blue-capped ifrit, also known as the blue-capped ifrita, is a small and insectivorous passerine species currently placed in the monotypic family, Ifritidae. Previously, the ifrit has been placed in a plethora of families including Cinclosomatidae or Monarchidae. Blue-capped ifrits are considered an ancient relict species endemic to New Guinea. This corvoid species originally dates back to the Oligocene epoch, on a series of proto-Papuan islands, with minimal known evolutionary divergences.

<i>Phyllobates</i> Genus of amphibians

Phyllobates is a genus of poison dart frogs native to Central and South America, from Nicaragua to Colombia. There are 3 different Colombian species of Phyllobates, considered highly toxic species due to the poison they contain in the wild.

<i>Phyllobates aurotaenia</i> Species of amphibian

Phyllobates aurotaenia is a member of the frog family Dendrobatidae, which are found in the tropical environments of Central and South America. First described by zoologist George Albert Boulenger in 1913, P. aurotaenia is known for being the third most poisonous frog in the world. It is the smallest of the poison dart frogs in the Phyllobates genus and is endemic to the Pacific coast of Colombia.

<span class="mw-page-title-main">Mimic poison frog</span> Species of amphibian

Ranitomeya imitator, is a species of poison dart frog found in the north-central region of eastern Peru. Its common names include mimic poison frog and poison arrow frog, and it is one of the best known dart frogs. It was discovered in the late 1980s by Rainer Schulte who later split it up into more subspecies; describing each as a specific color morph, and sometimes having a separate behavioral pattern. The acoustics, morphs, and behavior of the species have been extensively researched.

<span class="mw-page-title-main">Golfodulcean poison frog</span> Species of amphibian

The Golfodulcean poison frog or Golfodulcean poison-arrow frog is a species of frog in the family Dendrobatidae endemic to Costa Rica.

<span class="mw-page-title-main">Melampitta</span> Family of birds

The melampittas are a family, Melampittidae, of New Guinean birds containing two enigmatic species. The two species are found in two genera, the greater melampitta in the genus Megalampitta and the lesser melampitta in the genus Melampitta. They are little studied and before being established as a family in 2014 their taxonomic relationships with other birds were uncertain, being considered at one time related variously to the pittas, Old World babblers and birds-of-paradise.

<span class="mw-page-title-main">Pumiliotoxin 251D</span> Chemical compound

Pumiliotoxin 251D is a toxic organic compound. It is found in the skin of poison frogs from the genera Dendrobates, Epipedobates, Minyobates, and Phyllobates and toads from the genus Melanophryniscus. Its name comes from the pumiliotoxin family (PTXs) and its molecular mass of 251 Daltons. When the toxin enters the bloodstream through cuts in the skin or by ingestion, it can cause hyperactivity, convulsions, cardiac arrest and ultimately death. It is especially toxic to arthropods, even at low concentrations.

<span class="mw-page-title-main">Melyridae</span> Family of beetles

Melyridae are a family of beetles of the superfamily Cleroidea.

<span class="mw-page-title-main">Poisonous amphibian</span> Amphibians that produce poison

Poisonous amphibians are amphibians that produce toxins to defend themselves from predators.

<i>Choresine</i> Genus of beetles

Choresine is a genus of beetles that belong to the Melyridae family. This genus of beetle is known to have high levels of batrachotoxins and is believed to be a possible toxin source for Pitohui and Blue-capped ifrit birds in New Guinea. Collections from Herowana in the Eastern Highlands Province that tested positive for batrachotoxins included the more abundant C. pulchra, the less abundant C. semiopaca and the two infrequent C. rugiceps and C. sp. A, the latter as yet unnamed. The locals advise against allowing these beetles to touch the eyes or sweaty face as a severe burning sensation can result. These species are all described as having metallic blue-violaceous elytra and a yellow and blackish pronotum. The name "nanisani" is used by villagers in Herowana equally for this group of insects, the numbing, tingling, burning sensation they cause and the Blue-capped ifrit.

<span class="mw-page-title-main">Rufous shrikethrush</span> Species of bird

The rufous shrikethrush is a species of bird in the family Pachycephalidae.

<span class="mw-page-title-main">Toxungen</span>

Toxungen comprises a secretion of one or more biological toxins that is transferred by one animal to the external surface of another animal via a physical delivery mechanism. Toxungens can be delivered through spitting, spraying, or smearing. As one of three categories of biological toxins, toxungens can be distinguished from poisons, which are passively transferred via ingestion, inhalation, or absorption across the skin, and venoms, which are delivered through a wound generated by a bite, sting, or other such action. Toxungen use offers the evolutionary advantage of delivering toxins into the target's tissues without the need for physical contact.


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