They are actually passerine birds belonging to the genusCorvus and family Corvidae.
Their body size may vary from small pigeon to large wild raven.
They are the inhabitants of temperate regions except South America.
The genus was described by Linnaeus for the first time in his 18th century work Systema Naturae.
The name of the genus has been derived from a Latin word meaning raven.
Fossils of crow have been obtained in Europe in large numbers but their relationship with most prehistoric birds is still unclear.
Common Raven, Australian Raven and the Carrion crows are always blamed for killing weak lambs as they are often seen feeding on the dead animals no matter how that animal died.
They are also known to imitate human voices just like the parrots.
They are often trained to speak and are very valuable birds in East Asia as they symbolize good luck.
They are also kept as pets by some humans.
In United States they are legally allowed to be killed around the months of August to the end of March as during this time they become a nuisance also acts as vectore for a number of diseases.
It is believed that crows first evolved in central Asia and then radiated towards North America, Europe, Australia and Africa.
They are known to produce to produce wide variety of calls for communication.
They are also known to respond to the call of other species.
They show remarkable features of intelligence.
Crows have a special place in literature and mythology.
According to the popular legends in Europe crows especially the ravens are considered as the harbringers of death because of their dark ugly looking black coloured body, big size, and horrible look.
It is believed that they feed on the carrion even of humans too.
In mythology also crows symbolize spiritual aspects of death.
Crows have been observed hovering around the cemeteries.
In Hinduism it is believed that people after death become crows and will come to eat in the form of crows to pick up the food.
In Mahabharata a famous battle is known that was fought between the crows and owls.
It is also believed that if a crow attacks a human ill omen will gather around that person and will bring bad luck.
Crows are also susceptible to viral attack.
American crow is susceptible to the attack of West Nile virus.
This disease has been recently introduced in North America.
This disease is very fatal and the American crows die within a week after getting infection only few are able to survive.
The virus is spreading at a faster rate.
Two American species are considered to be endangered because of habitat destruction.
Wild life needs our attention otherwise our beautiful animals will be lost forever.