<P> Female crows are considered sexually mature at about 2 or 3 years of age and males at 4 years . The Hawaiian crow's breeding season lasts from March to July; it builds a nest in March or April, lays eggs in mid-to - late April, and the eggs hatch in mid-May . Both sexes construct nests with branches from the native ohi'a tree strengthened with grasses . The crow typically lays one to five eggs (that are greenish - blue in color) per season, although at most only two will survive past the fledgling phase . Only the females incubate the 2--5 eggs for 19--22 days and brood the young, of which only 1--2 fledge about 40 days after hatching . If the first clutch is lost, the pair will re-lay, which serves to be helpful in captive breeding efforts . Juveniles rely on their parents for 8 months and will stay with the family group until the next breeding season . </P> <P> The ʻalalā 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 the native plants . Many of these plants rely on the ʻalalā 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 . The ʻalalā plays a key role in the maintenance of many indigenous plant species, which now could become a rarity in Hawaii's ecosystems, specifically the dry forests, without their main seed disperser . The Hawaiian crow has become known as a indicator species; the disappearance of the ʻalalā indicates serious environmental problems . </P> <P> The Hawaiian crow faces an ample number of threats in the wild, which are considered contributing factors to their 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 ʻalalā because they were believed to disturb crops . Illegal hunting has 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 the ʻalalā 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 . This directly relates to the primary cause of the Hawaiian crow's extinction, disease . </P> <P> Avian malaria is a parasitic disease of birds, caused by Plasmodium relictum, a protist affecting birds in all parts of the world . Usually this disease does not kill birds, however in an isolated habitat such as Hawaii, birds have lost evolutionary resistance and are unable to defend against the novel protist . Its main vector is the mosquito Culex quinquefasciatus, introduced to the Hawaiian islands in 1826 . This introduction can be attributed to birds club that brought nonnative species to replace birds that fell victim to the Avipoxvirus . At least 100 introductions have been documented in this manner . </P>

What factor is responsible for the reduction in the population of the local crow the alala
find me the text answering this question