Identification
Distinguishing Features: Adult birds differ from the Large-billed Crow by the presence of a white collar on the neck and chest. This white collar extends to the upper back, and when viewed from the side, the white on the shoulders encircles the base of the wings, forming a V-shape. The remaining plumage is entirely black with a purplish-red iridescence. The eyes, beak, and legs are all black.
Biology and Ecology
Breeding: The breeding season extends from March to July. The spherical nests are built on branches or at the tops of trees, often 30 meters or more above the ground (typically on silk-cotton trees, banyan trees, etc.). A pair or multiple pairs may nest on the same tree. The nests are constructed meticulously using small twigs and dry branches, tightly interwoven. Some twigs are up to 1.5 cm in diameter and 45 cm long. The nests are lined with a thin layer of dry leaves and feathers of birds, ducks, and chickens. Each clutch contains 3-4 eggs, with a slightly opaque white shell. Incubation lasts approximately 20-22 days.
Diet and Behavior: The diet consists of geckos, frogs, mice, earthworms, and insects. When nestlings are close to fledging and food is scarce, the Large-billed Crow will prey on newly hatched chicks and ducklings when allowed to graze on the fields, and it has also been observed carrying young corn cobs back to the nest to eat. Molting occurs annually from August to October.
Habitat and Habits: The Large-billed Crow is a resident species, nesting in coastal areas, estuaries, plains, midlands, and mountainous regions up to 1500 meters in elevation (Cao Bang, Lang Son, Bac Kan) near cultivated areas and human settlements. They typically forage in areas near wetlands, mudflats, and intertidal zones after the tide recedes. They also forage alongside the Large-billed Crow, White-vented Myna, etc. They are predators of small birds and newly hatched domestic fowl.
Distribution
Within Vietnam: From Northern Vietnam to Central Vietnam.
Worldwide: Eastern China (Hainan Island).
Value
Significance: This species is considered rare and can mimic human speech and the calls of other animals. It serves as a typical indicator species for environmental pollution.
Status
Historical and Current Population: Before approximately 1980, the species was still observed in many locations within its range. Currently, there is very little information available about the Large-billed Crow in its distribution areas. According to Nguyen Cu, it was rediscovered in Quang Ninh (Quang Yen district) in December 2001. The decline may be attributed to environmental pollution caused by the use of pesticides in agriculture, which has affected the species’ life and distribution.
IUCN Status: Data Deficient (DD).
Conservation Measures
Protection Status: Listed in the Vietnam Red Data Book (1992, 2000), categorized as Endangered (EN). Further research is needed to gather more information, investigate the causes, and identify threats that put the species at risk of extinction, in order to implement effective conservation measures.