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Birds make adorable pets. A pet bird can bring immense happiness in your life. You will never feel bored because that little, feathered-friend of yours will be there to entertain you. But did you know there are many birds that are poisonous? Since some of these bird species are rare, it makes them little studied among different bird categories.
Why Are Some Birds Poisonous?
Until recently, toxicity in birds had not been described as a trait in birds. It was only in the last two decades that literature started covering this subject.
- Poisonous birds obtain toxicity from the animals and plants they consume.
- Data obtained from studies revealed that toxicity in birds is not ancestral. Instead, this trait occurred as a result of evolution. This is especially true for the group of birds classified under Pitohui species. The most striking fact about these birds is that they exhibit unique behaviors attributed to their toxicity.
- The toxins in poisonous birds can also be viewed from an adaptation standpoint. In this regard, it is considered that the poisonous birds have developed histological and/or morphological adaptations for them to produce or store toxins, which is unique to them.
Poisonous Birds
Following is the list of known birds that are poisonous.
1. Hooded Pitohui(Chemical present – homoBTX)
The hooded pitohui (Pitohui dichrous) 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.
A medium-sized songbird with rich chestnut and black plumage, this species is one of the few known poisonous birds, containing a range of batrachotoxin compounds in its skin, feathers and other tissues. These toxins are thought to be derived from their diet, and may function both to deter predators and to protect the bird from parasites.
The close resemblance of this species to other unrelated birds also known as pitohuis which are also poisonous is an example of convergent evolution and Müllerian mimicry. Their appearance is also mimicked by unrelated non-poisonous species, a phenomenon known as Batesian mimicry. The toxic nature of this bird is well known to local hunters, who avoid it. It is one of the most poisonous species of pitohui, but the toxicity of individual birds can vary geographically.
A social bird, it lives in family groups and frequently joins and even leads mixed-species foraging flocks. The diet is made up of fruits, seeds and invertebrates. This species is apparently a cooperative breeder, with family groups helping to protect the nest and feed the young.
2. European Quail (Chemical present – coniine)
The common quail (Coturnix coturnix), or European quail, is a small ground-nesting game bird in the pheasant family Phasianidae. It is mainly migratory, breeding in the western Palearctic and wintering in Africa and southern India. It is potentially poisonous to humans, but only during the autumn migration (not during their return flight in spring). Quail poisoning is an acute dietary-toxicological syndrome.
With its characteristic call of three repeated chirps (repeated three times in quick succession), this species of quail is more often heard than seen. It is widespread in Europe and North Africa, and is categorized by the IUCN as “least concern”. It should not be confused with the Japanese quail, Coturnix japonica, native to Asia, which, although visually similar, has a call that is very distinct from that of the common quail. Like the Japanese quail, common quails are sometimes kept as poultry.
3. Little Shrike Thrush (Chemical present – batrachotoxin-A)
The Arafura shrike thrush (Colluricincla megarhyncha) is a species of bird in the family Pachycephalidae. This species was formerly considered a conspecific member of the little shrike thrush complex. Genetic investigations of New Guinea populations of the little shrike thrush indicated high levels of genetic divergence, suggesting it comprised more than one species. It is found in Australia, Indonesia, and Papua New Guinea. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests.
During a study of the toxicity of the genus Pitohui, two specimens of this species have been tested too. One of them did have traces of batrachotoxins similar to those found in the secretions of Central and South American poison dart frogs.
4. Blue-capped Ifrita (Chemical present – batrachotoxins – BTX)
The blue-capped ifrit (Ifrita kowaldi), also known as the blue-capped ifrita, is a small and insectivorous passerine species currently placed in the monotypic family, Ifritidae. Blue-capped ifrita 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.
As birds with weak flight abilities, blue-capped ifrita build nests about 1–3 meters (3–10 feet) above the ground in the branches of denser rainforest vegetation. These nests are made of plant fibers with some feathers. The parents tend to camouflage the outside of the nest with moss and liverworts. Ifrita lay small clutches with a typical nest containing only a single offspring. The nest camouflage, toxin excretion, and small clutch sizes may have derived from historically high rates of depredation and nest parasitism.
Blue-capped ifrita are among a small group of avian species that are poisonous. Ifrita excrete batrachotoxin into their feathers and skin in order to defend themselves against predators. Generally, batrachotoxin binds and permanently opens the sodium channels in nerve cells and can cause paralysis. The accumulation of toxins varies in individuals based on the region they are found in and this could be due to the availability of Choresine spp beetles, which are speculated to be the dietary cause of the toxin itself.
5. Northern Variable Pitohui (Chemical present – BTX)
A fairly large bird of lowland and foothill secondary forest and edge. As the name suggests, a variably plumaged bird. All have rufous underparts, but one is all rufous with yellow bill, the rest have dark bill and dark wings, some with blackish and others with gray hood.
All rufous birds are similar to Rusty Pitohui but lack the white eye. Black headed birds are almost identical to Hooded Pitohui, but Northern Variable is slightly larger and found at lower elevations. The variable song is a medium-pitch, warbled jumble and call, a nasal grating.
The northern variable pitohui (Pitohui kirhocephalus) is a species of pitohui in the family Oriolidae. It is found on New Guinea and a number of neighbouring islands. Its natural habitat is subtropical or tropical moist lowland forests. It is also one of the few known poisonous birds.
6. Red Warbler (Chemical present – neurotoxic alkaloids)
The red warbler (Cardellina rubra) is a small passerine bird of the New World warbler family Parulidae endemic to the highlands of Mexico, north of the Isthmus of Tehuantepec. It is closely related to, and forms a superspecies with, the pink-headed warbler of southern Mexico and Guatemala. The red warbler is an insectivore, gleaning primarily in understory shrubs.
There are three subspecies, found in disjunct populations, which differ primarily in the color of their ear patch and in the brightness and tone of their body plumage. The adult is bright red, with a white or gray ear patch, depending on the subspecies; young birds are pinkish-brown, with a whitish ear patch and two pale wingbars.
7. Spur-winged Goose (Chemical present – cantharidin)
The spur-winged goose (Plectropterus gambensis) is a large bird in the family Anatidae, related to the geese and the shelducks, but distinct from both of these in a number of anatomical features, and therefore treated in its own subfamily, the Plectropterinae. It occurs in wetlands throughout sub-Saharan Africa.
This species often occurs in open grasslands with lakes, seasonal pools, rivers, swamps and river deltas. Large inland rivers and lakes are perhaps most commonly inhabited, with saline lakes and upland areas generally being avoided, although the species can occur to an elevation of 3,000 m (9,800 ft) in eastern Africa. It is also absent from arid zones.
This bird is often poisonous due to its diet of blister beetles. The poison, cantharidin, is held within the tissue of the fowl resulting in poisoning of those that eat the cooked goose. 10 mg of cantharidin can kill a human.
8. Ruffed Grouse (Chemical present – coniferyl benzoate)
The ruffed grouse (Bonasa umbellus) is a medium-sized grouse occurring in forests from the Appalachian Mountains across Canada to Alaska. It is non-migratory. It is the only species in the genus Bonasa.
The ruffed grouse is sometimes incorrectly referred to as a “partridge”, an unrelated phasianid, and occasionally confused with the gray partridge, a bird of open areas rather than woodlands.
Ruffed grouse eat several plants known to cause toxic symptoms in humans, and some of these species exhibit distinctive seasonality while others remain available throughout the year.
9. Brush Bronzewing Pigeon (Chemical present – fluorine)
The brush bronzewing is similar in size and shape to the closely related common bronzewing (Phaps chalcoptera), however it’s shorter and stockier in appearance. These birds are relatively small and range in size from 25 to 33 cm. Both sexes are dark-olive brown on top, rich chestnut in colour along the nape and shoulder with blue-gray underparts. The brush bronzewing is named for the iridescent bars of blue and green across the inner secondary feather of each wing.
The brush bronzewing (Phaps elegans) is a species of bird in the pigeon family, Columbidae. It is endemic to Australia, with two bio geographically distinct subspecies.
The brush bronzewing is endemic to Australia, found in the South-West and South-East of the mainland with populations in Queensland, New South Wales, Victoria, South Australia, Western Australia and also Tasmania. This species favours dense coastal heathland, wet or dry sclerophyll forests, woodlands and some mallee areas. Habitats with dense shrub layers and foliage, including native species such as Banksia, Acacia, Melaleuca or Leptospermum, allow these cautious birds to find cover.
10. Eurasian Hoopoe (Chemical present – di-methyl sulphide)
The Eurasian hoopoe (Upupa epops) is the most widespread species of the genus Upupa, native to Europe, Asia and the northern half of Africa. The Eurasian hoopoe is a medium-sized bird, 25–32 cm (9.8–12.6 in) long, with a 44–48 cm (17–19 in) wingspan. It weighs 46–89 g (1.6–3.1 oz). The hoopoe has a characteristic undulating flight, which is like that of a giant butterfly, caused by the wings half closing at the end of each beat or short sequence of beats. Adults may begin their molt after the breeding season and continue after they have migrated for the winter.
The call is typically a trisyllabic oop-oop-oop, which may give rise to its English and scientific names, although two and four syllables are also common. In the Himalayas, the calls can be confused with that of the Himalayan cuckoo (Cuculus saturatus), although the cuckoo typically produces four notes. Other calls include rasping croaks, when alarmed, and hisses. Females produce a wheezy note during courtship feeding by the male.
The diet of the Eurasian hoopoe is mostly composed of insects, although small reptiles, frogs and plant matter such as seeds and berries are sometimes taken as well. It is a solitary forager which typically feeds on the ground. More commonly their foraging style is to stride over relatively open ground and periodically pause to probe the ground with the full length of their bill.
These birds have evolved and are adapted to produce an awful smelling liquid using their uropygial glands, highly concentrated with di-methyl sulfide that offers them a chemical defense against predators. The ability to produce the foul liquid is evidenced in nestlings and breeding birds. It offers protection to these birds in critical parts of their lifecycle. This form of defense is evidenced in their sister species named the green woodhoopoe, which is essential because it gives them group defense.
Conclusion
These poisonous birds have over the years developed morphological and histologic adaptations that allow them to use their toxic weaponry at specific points in their life cycles mostly in keeping off predators and/or parasites.
Quiz on Birds
Recommended Reading
- Birds That Sleep While Flying
- Talking and Singing Birds – Birds That Mimic
- Bird That Can Fly Backwards
Image Credit: Bird tree photo created by wirestock – www.freepik.com
