A very intelligent species (5), the house crow is always alert and wary, walking or hopping along the ground with its wings flicking nervously (2). It is a social, non-migratory species which gathers in noisy flocks throughout the year and forms massive roosts (2) (3) (5) (6). Such flocks may number hundreds or thousands of individuals, and the house crow is known to gather together with groups of parakeets (Psittacidae) and mynahs (Sturnidae) in mangroves or plantations. The house crow flies back to its foraging grounds just before dawn breaks (2).
An omnivorous scavenger, the house crow has a varied diet, feeding on everything from carrion, seeds and nectar to invertebrates and small vertebrates (2) (4) (5) (6). This species tends to take advantage of rubbish tips, markets, farms, fisheries and abattoirs, scavenging for scraps and offal (2) (3) (4) (5), and even sometimes feeds on human corpses (2).
The house crow raids crops, damaging them by pulling seedlings up by the roots, and it is known to steal grain, rice and other food from buildings (2) (3) (5). This species also feeds on the eggs and nestlings of many bird species, such as those of herons and egrets, and its agility enables the house crow to enter weaver bird colonies. Aerial sallies are undertaken to pluck flying ants from the air, and fish and aquatic insects are snatched from the water following plunge-dive type movements. A bold and aggressive species, the house crow rides on the backs of large mammals to pick off ticks and other parasites, and it has also been reported to peck at any open sores within its reach (2).
The breeding season of the house crow varies depending on the geographic location (2). In many parts of its range, such as in India, the house crow breeds at the beginning of the wet season, from April to June (2) (6), whereas in East Africa this species breed between September and June (6). The house crow forms long-term pair bonds and is generally considered to be a monogamous species, but many individuals are reported to be rather promiscuous (2).
The house crow is usually a solitary nester (2) (6), and typically nests close to human habitation (5) (7). The untidy nests of the house crow are often built in trees, but are also found on building ledges, electricity pylons and streetlamps (2) (5) (6) (7). Nests may be made of sticks and twigs, or from man-made materials such as metal and wire gathered from rubbish tips (2) (5) (7), and are usually lined with soft materials (2). A wire nest can weigh up to an impressive 25 kilograms. Although both sexes collect the nest material, it is usually the female that builds the nest (2).
The female house crow lays three to five eggs per clutch (6) (7), with an average of four (2), and the eggs are extremely variable both in shape and colour (7). Incubation lasts 16 to 17 days, and is thought to be carried out by the female alone, although the male may relieve her for short periods. House crow chicks are fed by both parents, and remain in the nest for three to four weeks (2). The house crow may produce two clutches of eggs per breeding season (2) (6).
In its native range, the house crow is known to be predated by other corvids, birds of prey, snakes and monkeys. However, it has few predators in many areas where it has been introduced (6).