You may be used to having tanagers visiting your back garden or bird feeder. However, there are a few critically endangered species of tanager.
There are about 40 species of true tanagers and four are critically endangered. These tanagers are rare due to poaching, habitat destruction, logging, and deforestation.
MANGROVE FINCH
The mangrove finch is endemic to the Galapagos Islands and belongs to the group of birds known as ‘Darwin’s finches.’
Adult mangrove finches possess dark brown plumage that fades to olive near the rump and white, slightly striped underparts. After multiple yearly molts, males get black feathers on the head and neck.
Mangrove finches scrape the scales of tree bark with their long and pointed beaks, allowing them to gather insect prey from beneath and investigate through the dead leaves.
How many are present: Around 20 and 40 mature individuals
Since 2009, no more than 20 breeding pairs have been documented in a year. In 2019, a population of 13 territorial pairs was recorded, of which only ten reproduced. As a result, the population is predicted to be between 20 and 40 mature adult individuals. The total population is estimated to be between 80 and 100 individuals.
Where do they live?
It lives in thick mangrove forests. The species’ preferred habitat appears to be structurally distinct from areas where it is missing. This suggests that it has delicate habitat preferences.
They prefer mangroves with towering trees, little canopy cover, and plenty of leaf litter and dead wood.
Mangrove finches are endemic to the Galápagos Islands. It was reported from the islands of Fernandina and Isabela. However, newer surveys have failed to record the species on Fernandina Island.
The surviving birds are currently restricted to two geographically distinct groups on Isabela, one on the island’s west coast and a second tiny population on its east coast.
Threats
The mangrove finch population is declining due to parasitism and predation by invasive species. Breeding locations have high black rat populations that are unmanaged. This has been thought to be the main cause of the high rate of nesting failures.
The most severe threat at the moment is the blood-sucking nest parasite Philornis downsi, which is present in every nest. It has a high infestation rate, averaging 42 parasites per nest. It kills almost all chicks in the absence of any management.
The declining population of black mangrove trees is also posing a threat to the population of mangrove finches. However, they are not essential for their survival but are preferred for nesting by finches.
Changes in rainfall are also detrimental to the population, as fewer females reach reproductive age. Females do not react to males and do not form pairs and breed when the environment is dry.
These environmental stresses are expected to worsen due to human-caused climate change.
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GOUGH FINCH
Gough finch is a large finch that has a dagger-like beak. Male and females have different appearances. Males are usually olive in color with yellow eye-ring and black throats, whereas females are brown and lack black throats. Juveniles are similar to females, but they are heavily streaked.
Invertebrates make up about 80% of its diet, although it also consumes fruit, grass seeds, broken eggs from birds, and grass.
How many are present: 1000 mature individuals
According to estimates, the population of Gough finch comprises of1000 mature individuals. The population trend has been decreasing for many years.
Where does it live?
Gough finch is endemic to Gough island in the South Atlantic ocean. It is found in subantarctic grasslands and temperate shrublands.
It is most abundant up to 800 m in tussock-grassland and wet heath. It is present in low densities in fern bush and peat bogs.
Threats
Excessive predation by invasive house rat species has reduced the Gough Finch population in lowland regions. Over the previous 15 years, the proportion of juveniles has decreased from 50% to 20%.
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CHERRY-THROATED TANAGER
The Cherry-throated Tanager is a remarkable and elegant bird with its grey back, black mask, and vivid red throat. It is also one of the rarest birds. Due to its bright red neck, the Cherry-throated Tanager is referred to as Saira-apunhalada (“stabbed tanager”) in Portuguese.
How many are present: 30-200 mature individuals
This species is thought to be diminishing during 11 years at a rate of 10–19 percent. Only 30-3200 mature individuals are estimated to be alive.
Where does it live:
Cherry throated tanager is confined to several locations in the Atlantic Forest in Espirito Santo, Brazil. Still, it is possible that it also lives in nearby areas of Minas Gerais and Rio de Janeiro.
It is primarily found in the humid montane forest canopy between 850 and 1,250 meters above sea level.
Birds appear to prefer moss and lichen-covered branches as they browse inside the interiors of large trees’ crowns, occasionally descending toward the edge of the forest. It has never been documented in open forests and typically avoids secondary forests and plantations.
However, if the canopy cover is deep enough, it may use plantations and secondary rainforests as corridors to migrate between areas of preferable habitat.
Threats
Habitat loss is the primary reason which is causing the decline of the population of Cherry throated tanager.
The unauthorized extraction of palm oil, the growth of coffee plantations, small-scale firewood harvesting, and large-scale timber harvesting, particularly for the manufacturing of charcoal, are all threats related to the loss of forests.
Habitat alteration in housing and commercial developments also poses hazards to cherry-throated tanager.
MEDIUM TREE FINCH
The medium tree-finch is a tiny, swift bird. Its beak has a somewhat curved top and bottom edge and is slightly bigger than it is deep.
The male is distinguished by a black hood, brownish-olive upper parts, and a yellowish belly. The female has a tan body with creamy underparts. The breasts of both sexes contain subtle striping. The beak of a breeding male is black, whereas that of a female and a non-breeding male is orange.
It explores tree bark fissures and looks under twigs and foliage for insects, nectar, new buds, and leaves to eat.
How many are present: 600-1700 mature individuals
In 2008, the population was projected to be 1,660 individuals at its maximum. It is generally put in the range of 1,000-2,499 individuals, from which it can be estimated to be 600-1,700 mature individuals.
According to an avian survey conducted in 2010, the entire population was estimated to be 1620.
Where do they live?
It lives mostly at elevations of 300-400 meters. It inhabits montane evergreen and tropical deciduous forest and Scalesia-zone wet scrub.
Medium tree finches are native to only Floreana Island in the Galápagos Islands. It is uncommon to rare on the shoreline and present in small numbers in the highlands.
Threats
The most severe threat is the invasive ectoparasite Philornis downsi, which inhabits finch nests on Floreana and accounts for 41% of nestling mortality.
Since its only intact habitat is next to agricultural land that has been cleared and has fruit trees, which the adult fly prefers, it is believed to be at an increased danger of fly parasitism.
Introducing different predators, including pigs, donkeys, dogs, cats, and rats, severely threatens finch populations.
Habitat clearing and destruction, along with habitat alteration by livestock and invasive species, negatively impact the medium tree finch population.
This species is possibly vulnerable to climate change due to its alpine distribution, which is closer to the maximum altitude within its range.
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