The blue-capped ifrit (Ifrita kowaldi), is a species of small passerine bird in the monotypic family, Ifritidae, native to the montane rainforests of New Guinea.[2][3][4][5]. These birds are insectivorous and are notable for their distinctive blue crown and presence of batrachotoxin, a potent neurotoxin, in their feathers and skin.[6][7][8][9][10][11] This chemical defense is believed to come from their diet, particularly Choresine beetles.[9][10][11][12][13] Despite their toxicity, blue-capped ifrits are non-aggressive and typically found in small groups within high altitude forest habitats.[8][5][14] Although they are currently listed as Least concern by the IUCN, their population is slowly declining due to habitat disturbance and limited conservation measures.[6][14]
The blue-capped ifrit is 16–17cm (6.5–6.5in) long and weighs 34–36g (1.2–1.3oz).[6] The bird shows brown upperparts (top side of the bird including head, back, wings, and tail) with finely dotted wing edges and light-yellow underparts (the underside of bird, including belly, throat, chest, and under the wings and tail).[7]
The head is marked with a bright blue cap outlined in black, a small black spot on the crown, and a long white stripe running besides the eye. A thin black strip is within this strip, and the eye itself is encircled by a narrow white ring.[7]
Ifrits tend to have more stout body shapes with broad chests. Their wings are short and rounded while their legs are booted, having feathers down to their stout and clawed feet.[2]
The species is sexually dimorphic, with ear streak coloration being white in males and more tawny yellow in females.[2] Additionally, males have darker markings around the eyes and have more vivid coloration on the head and neck, females have paler markings around the eyes, and juveniles resemble females but have a light brown forehead.[6]
Taxonomy
The blue-capped ifrit (Ifrita kowaldi) is the sole member of the family Ifritidae, making the family monotypic, meaning it is the only species in its family.[2][3]The bird belongs to the order Passeriformes and the superfamily Corvoidea, a large group that also includes crows, birds of paradise, and jays.[15][16]
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.[17]
Common names
The blue-capped ifrit is known a variety names in different languages.[16]
The species mainly lives in subtropical and tropical moist montane forests and is highly dependent on the forest ecosystem.[14] It is found from roughly 100 to 4,000 meters (210- 12,070 ft) in elevation, though it is most commonly found at altitudes of 1,500 meters (4,900 feet) or above.[5][14]
Toxicity
Batrachotoxin molecule
The blue-capped ifrit is one of the few birds that accumulate batrachotoxin (BTX) in their feathers and skin.[9][10][11]This potent neurotoxin is thought to be deadlier than cyanide and cause sneezing, irritation, and allergic reactions in humans who handled the bird.[11][12]
Source of the Toxin
Batrachotoxin is thought to enter the Ifrit's body through its diet, most likely from Chroesine beetles from the Melyridae family.[9][10][11][12][13] Some researchers believe these beetles may gain the toxin from soil mites or certain plants.[12] The chemical provides the bird with strong protection against predators and parasites.[9] Levels of BTX can vary between species and individuals, but the blue-capped ifrit and the hooded pitohui (Pitohui dichrous) showed the highest concentrations.[10] In 2023, scientists discovered two additional toxic bird species from Papua New Guinea, highlighting how little is still known about toxic avians.[12][13]
Mechanism, Effects, and Adaptations
Batrachotoxin (BTX) works by holding the sodium ion channels in muscle and nerve cells open, which can cause muscle paralysis and potentially death.[10][11][12] The blue-capped ifrit, however, is resistant to its own toxin because of a mutation in the SCN4A gene which codes for the NAV1.4 sodium channel that helps muscles work. This mutation changes the channel's shape so the BTX can't bind properly, explained by target-site insensitivity. Similar mutations are found in poison dart frogs, providing an example of convergent evolution.[9][10][12]
Some studies suggest that the sodium channels remain partly sensitive, so scientists believe that the bird may also produce a protein that "soaks up the poison" safely.[12] Additionally, because the blue-capped ifrit have to move BTX from its stomach to its feather and skin, researchers believe there is a transporter protein that distributes it.[12]
Behavior
Mating
Nesting occurs from August to November. Nests are built from green moss and leaf fern and are usually placed 2-3 meters (6.5-10 ft) above the ground, often in a fork if a small tree or sapling.[6][8] Each clutch typically contains a single white egg with black and purple spots for camouflage.[6] Both parents participate in nest building and chick care, and the small clutch size points to a high investment in the offspring (k-selected species).[6] The birds toxin covered breast and belly feathers may rub off on the egg or nest, which offers chemical protection from predators.[8]
Vocalization
The blue-capped ifrits song produces an upbeat "toowa-tee!", along with a short dry "Wik" call.[7]
Diet
The species primary feed on insects and worms, which indicate insectivorous feeding behaviors.[6][7][8] They forage carefully through moss, branches, and tree trunks.[8] Occasionally, the bird will eat soft fruits to supplement a food source.[6] The blue-capped ifrits toxicity is gained though their diet, mostly from Choresine beetles of the Melyridae family.[9][10][11][12][13]
Social and Territorial Behavior
Blue capped ifrits are often seen in small groups of up to six, suggesting social behavior. The birds are rarely seen alone, which may indicate that are not territorial.[8]
Conservation status
Ifrits are of least concern because they have a large range and have relatively large population.[6] Some of their habitat is within conservation sites.[18] Although the birds are toxic, they have not been found in bird markets or sold online in Indonesia, unlike the pitohuis. The species is not officially protected by Indonesian law, because the trade is unregulated, so they could be sold illegally.[11] While the population is slowly decreasing, the decline is not fast enough for the species to be considered vulnerable.[14] However, data shows that tree cover in their habitat has declined by 1.7% over the past decade, which has contributed to a population decline of up to 19%.[14]
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