ʻalalā
The Hawaiian crow or ʻalalā (Corvus hawaiiensis ) is a species of bird in the crow family, Corvidae, that is currently extinct in the wild, though reintroduction programs are underway. Today, the Hawaiian crow is considered the most endangered of the family Corvidae. Some Native Hawaiians consider the Hawaiian crow an ʻaumakua (family god).
Hawaiian crows are about the size of the Carrion crow at 48–50 cm (19–20 in) in length, but with more rounded wings and a much thicker bill. They have soft, brownish-black plumage and long, bristly throat feathers; their feet, legs, and bills are black.
Before the Hawaiian crow became extinct in the wild, the species was found only in the western and southeastern parts of Hawaii. These birds lived in dry and mesic forests on the slopes of Mauna Loa and Hualālai volcanos.
Hawaiian crows are social and often gather in small flocks. They are diurnal and spend daylight hours pent foraging on trunks, branches, and foliage for invertebrates. They feed in a woodpecker fashion, flaking bark and moss from trunks or branches to expose hidden insects, foraging primarily on ohia and koa, the tallest and most dominant trees in their habitats. They only occasionally forage on the ground, but only for a limited amount of time for risk of predators. Hawaiian crows are very intelligent birds. They can use sticks as tools to extract food from holes drilled in logs. The juveniles are even able to use tools without training or social learning from adults, and it is believed to be a species-wide ability. In order to communicate with each other, Hawaiian crows use a call described variously as a two-toned ‘caw’ and as a screech with lower tones added, similar to a cat's ‘meow’. In flight, they produce a wide variety of calls including a repeated ‘kerruk, kerruk’ sound and a loud ‘kraa-a-a-ik’ sound. They also make a ‘ca-wk’ sound, have a complex, burbling song, and make a variety of other sounds as well.
Hawaiian crows are omnivorous. The main portion of their diet consists of invertebrates such as isopods, land snails, and arachnids. Fruits are the second most dominant component of their diet. Passerine nestlings and eggs are consumed most frequently in April and May, during their breeding season. Hawaiian crows also prey on small birds and eat flowers, nectar, and various plant parts, including flower petals.
Hawaiian crows are monogamous and usually form long-term pair bonds. Their breeding season lasts from March to July. The birds build their nest in March or April and lay eggs mid-to-late April. Both parents construct the nest with branches from the native ohi’a tree strengthened with grasses. The female typically lays 1-5 eggs (that are greenish-blue in color) per season, although at most only 2 will survive past the fledgling phase. Only the female incubates the eggs for 19-22 days and broods the young, which fledge about 40 days after hatching. Juveniles rely on their parents for 8 months and will stay with the family group until the next breeding season. Young females become reproductively mature at about 2 or 3 years of age and males at 4 years.
The Hawaiian crow suffers from an ample number of threats in the wild, which are considered contributing factors to its extinction in the wild. Small population size makes the species more vulnerable to environmental fluctuations, leading to a higher likelihood of inbreeding, which could result in lethal deformities. Unlike most crows, Hawaiian crows did not adapt well to human presence. Persecution by humans is another threat to their survival. Farmers have shot these birds because they were believed to disturb crops. Illegal hunting continued even after legal protection was granted to the crows. Humans have also caused habitat degradation and deforestation through agriculture, ranching, logging, and non-native ungulates. Loss of canopy cover exposes Hawaiian crows to dangerous predators. Chicks are vulnerable to tree-climbing rats and, after they leave their nests, to cats, dogs, and mongooses. Deforestation also increases soil erosion and the spread of invasive plants and mosquitoes which directly relates to the primary cause of the Hawaiian crow's extinction, disease.
According to IUCN Red List, the last two known wild individuals of the Hawaiian crow disappeared in 2002, so the species is now classified as Extinct in the Wild (EW). Some individuals remain in captive breeding facilities and a reintroduction plan is being developed.
The Hawaiian cow was one of the largest native bird populations in Hawaii. Its disappearance in the wild has had cascading effects on the environment, especially with the seed dispersal of native plants. Many of these plants rely on these birds not only for seed dispersal, but also for seed germination as seeds are passed through the crow's digestive system. Without seed dispersal, the plants have no means of growing another generation. Hawaiian crows play a key role in maintaining many indigenous plant species, which now could become a rarity in Hawaii's ecosystems, specifically the dry forests, without their main seed disperser. These birds have become known as indicator species and their disappearance indicates serious environmental problems.
