Wednesday, May 13, 2015

Featured Bird: 4 birds that are TOXIC

In the wild, most birds (with the exception of raptors) are generally recognized as "prey species". This means that many birds are generally foragers that are in turn susceptible to being attacked by predatory animals such as mammals, reptiles, and even larger birds.  Evolutionary pressure over the years has resulted in a wide range of self-defense mechanisms employed by birds in order to elude or discourage predators ranging from camouflaging plumage, communal roosting, bluffing, and may more. While many of these methods have been of interest to ornithologists all over the world, none perhaps can match the various species of birds who are known to use toxins as a means of self-defense. To date, no bird species is known to actively inject, or produce, venom but there are a select few species of bird that can produce poisons on their skins that make them untouchable and unpalatable to the many host of avian predators out there. The following are a list of the 4 iconic species of toxic birds.

1. The Spur Winged Goose

A goose is certainly one of the less exotic of birds on the list and the spur wing goose is considered to be highly abundant throughout its range. A fairly handsome bird with black and white feathers, and an orange or reddish bill, the spur-winged goose is a native to the African Wetlands and is often considered as one of the contenders for the title of the "World's Largest Wild Goose". Tough the bird resembles other species of geese in many ways, the spur winged goose is the exception in that it is the only species of goose known to sequester poisons in its very flesh, making it completely unpalatable and untouchable from both predators and humans alike. The poisons housed in the tissue of the goose is known as cantharidin, a toxin capable of causing severe chemical burns, and is sequestered by the goose from the blister beetles that it eats in its natural environment. The poison is present in the goose even when it is cooked and ingestion of spur-winged geese meat has been known to cause severe poisoning in human beings. Cantharidin is lethal when ingested by humans in doses as small as 10mg and may often cause damage to the gastrointestinal lining and urinary tract, and permanent renal damage. This, of course, is very fortunate for the goose as it often finds itself avoided by predators, animals and humans alike.

This is one goose that won't be served on anyone's dinner table anytime soon! 
2. The Hooded Pitohui

Arguably one of the more striking of candidates on the list, the pitohui, or New Guinean Oriole, is a small, beautifully colored bird that is also widely distributed across its range. The hooded pitohui, along with its cousins the variable pitohui and the rusty pitohui, were one of the first few documented species of poisonous birds. Much like the goose, the pitohui does not produce this poison on its own. Rather, the poison is sequestered from various beetles and insects that compose the bird's natural diet. The poison is a kind of neurotoxin called homobatrachotoxin and is secreted, presumably by oil glands, onto the bird's skin and feathers. Handling the bird may cause a reaction in those whose skins are particularly sensitive. In many humans the sensation is often described as acute numbness or tingling of the nerves. The poison in the bird's skins makes it difficult to consume and its brilliant orange and black colors often warns predators that consuming it would not be kind of the palate. They are sometimes consumed by predators, and local New Guineans, during desperate measures but in order to consume them safely, the bird's skin and feathers must be thoroughly removed. Among the local Papua New Guineans, this beautiful bird has unfortunately gained the nickname of "Rubbish Bird", though this is probably a good trade off for the bird who almost never gets eaten. 

The bright colors of the pitohui are believed to serve as a form of aposematism: red, orange, and yellow on black is often recognized by many in the animal kingdom as cautionary colors that advertise an animal's toxicity. 

3. The Blue Capped Ifrit

The Blue Capped Ifrit employs a similar line of defense as the Pitohui in that the poison it sequesters is of a similar compound and is also though to be obtained from the various insects consumed by the bird in its everyday life.  The blue-capped ifrit is a unique bird in that it is the only member of its genus. Like the Pitohui, it is widely spread out across New Guinea and is also considered to be of "bad eating" among the locals. Because this toxin is sequestered and not produced, however, birds who do not consume enough poisonous beetles on a day-to-day basis may exhibit a lower toxicity than birds who are able to find them everyday.
The blue-capped Ifrit.
4. The Common Quail

This is one bird on the list that may surprise many. The common quail is widely known across the world as a delicacy that some choose to partake in. In fact, the common quail is so widely consumed that not many people are aware of the bird's potential for toxicity.  In the wild, quail are migratory birds and often travel a considerable distance in search of more favorable conditions during the winter. During their journey across the European continent, the common quail are believed to consume a large variety of plants, many of which may be poisonous in nature. Many of these poisons are broken down by the bird's digestive tract but some, it would seem, linger on within the very flesh of the bird itself. When consumed, the poison results in a sickness known as coturnism that ultimately results in muscle cell breakdown. Most of the quail that are consumed these days are farmed, which greatly reduces the risk of the disease in modern times, but back in the day when the hunting of quail on their migratory passage was widespread, the occurrence of coturnism in quail-eating nobles, was a very common thing. Furthermore, historical accounts seem to illustrate that the poison is stable and can persist even in quail that have been pickled and preserved for as long as four months! The poison is also fat-soluble and can be transferable to other foods cooked in the fat or oil of affected quails. Little is known about the poisonous compounds that are stored in the flesh of affected quails or the plants that give them their toxicity and due to the fact that a large majority of consumed quail is presently farmed, coturnism may be one of the rare health conditions that is wiped out long before it is completely understood. 

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