CROW

CROW

·        Introduction

crow may be a cosmopolitan genus of medium-sized to massive birds within the bird family. The genus includes species normally called crows, ravens, rooks and jackdaws; there's no consistent distinction between "crows" and "ravens", and these appellations are assigned  to totally different species principally on the idea of their size, crows typically being smaller than ravens.

·        description

Crows species are all black or black with little white or grey plumage. They are stout with strong bills and legs. Sexual dimorphism is limited.

·        Evolutionary history and systematics

The members of the Corvus square measure believed to own evolved in central Asia and radiated out into North America, Africa, Europe, and Australia.

The latest evidence[6] concerning the evolution indicates descent among the archipelago bird family. However, the branch that might manufacture the fashionable teams like jays, magpies, and large, preponderantly black Corvus species had left archipelago and were targeted in Asia by the time the Corvus species evolved. Corvus has since re-entered Australia (relatively recently) and made 5 species with one recognized taxonomic group.

behavior

Species

·        Communal roosting

Crows take in massive communal roosts listing between two hundred and tens of thousands of people throughout nonbreeding months, significantly within the winter. These gatherings tend to happen close to massive food sources like garbage dumps and searching centers.

·        Play

Countless incidents are recorded of corvids at play. Many behaviourists see play as an important quality in intelligent animals.

·        Calls

Crows and the other members of the genus make a wide variety of calls or vocalizations.[12] Crows have also been observed to respond to calls of other species; presumably, this behavior is learned as a result of it varies regionally.[13] Crows' vocalizations square measure complicated and poorly understood. Some of the many vocalizations that crows make are a "koww", usually echoed back and forth between birds, a series of "kowws" in discrete units, a long caw followed by a series of short caws (usually created once a bird flies from a perch), an echo-like "eh-aw" sound, and more. These vocalizations vary by species, and among every species they vary regionally. In several species, the pattern and range of the many vocalizations are discovered to alter in response to events within the surroundings (e.g. arrival or departure of crows).

·        Intelligence

As a group, crows show exceptional samples of intelligence. Natural history books from the eighteenth century recount associate degree often-repeated, however unproved  report of "counting crows" — specifically a crow whose ability to count to 5 (or four in some versions) is established through a logic entice set by a farmer.[14][15] Crows and ravens often score very highly on intelligence tests. Certain species prime the vertebrate intelligence quotient scale.[16] Wild hooded crows in Israel have learned to use bread crumbs for bait-fishing.[17] Crows engage in a kind of mid-air jousting, or air-"chicken" to establish pecking order. They have been found to have interaction in activities like sports,[18] tool use, the power to cover and store food across seasons, episodic-like memory, and the ability to use individual expertise in predicting the behavior of environmental conspecifics.

·        diet

Crows square measure omnivorous , and their diet is very diverse. They will eat nearly something, including other birds, fruits, nuts, mollusks, earthworms, seeds, frogs, eggs, nestlings, mice, and carrion. The origin of putting scarecrows in grain fields resulted from the crow’s incessant damaging and scavenging, though crows assist farmers by feeding insects otherwise interested in their crops.

·        Lifespan and disease

Some crows could live to the age of twenty, and also the recentest famous American crow within the wild was virtually thirty years old.[32] The oldest documented captive crow died at age 59.[33]

The American crow is extremely at risk of the recently introduced North yankee strain of West river virus.[34] yankee crows usually die inside one week of effort the illness and extremely few survive exposure.

·        Problems and methods of control

Intelligence and social structures build most crow species variable and opportunist. Crows ofttimes cause injury to crops and property,[36] strew trash, and transfer disease. In densely inhabited areas round the world, corvids square measure usually thought to be nuisance animals.[37] Crows are protected in the U.S. under the federal Migratory Bird pact Act of 1918, however thanks to their perceived harmful nature, control of the species is allowed in certain areas. Because of their intelligence, management is commonly troublesome or costly. Methods for management embody looking, chemical immobilization, harassment and scare tactics, and trapping. Before any live is employed to confine, trap, kill, poison, immobilize, or alter the habits of any wild bird species, a person must check local, state, and federal regulations pertaining to such actions.

·        As food

Crows were hunted for survival by Curonians, a Baltic tribe,[42] when common food was exhausted and the landscape changed so that farming was not as productive during the 18th and 19th centuries. Fishermen supplemented their diet by gathering coastal bird eggs and conserving crow meat by seasoning and smoking it. It became a standard food for poor folks and is documented in a very literary work, "The Seasons" by K. Donelaitis. After the nonhunting policy was lifted by the Prussian government in 1721–24 and alternative food supplies increased, the practice was forgotten. The tradition re-emerged when warfare I; in marketplaces, butchered crows that were asked for and acquired by town were common. The hunted crows were not the local, but the migrating ones; each year during the spring and autumn, crows migrated via the Curonian Spit between Finland and the rest of Europe. In 1943, the government even issued a hunting quota for such activities. Crows were usually caught by attracting them with smoked fish or grains soaked in spirits and then collecting them with nets. It was employment for the aged or young United Nations agency were unable to travel to ocean to fish, and it had been common to catch one hundred fifty to two hundred birds throughout a hunting day.

·        Human interaction

The common raven and New World vulture are blessed for killing weak lambs and square measure usually seen uptake freshly dead corpses most likely killed by different means that. The Australian raven has been documented chasing, attacking, and seriously injuring lambs.[43] Rooks have been blamed for eating grain in the UK and brown-necked ravens for raiding date crops in desert countries.[44]

Crows are shown to possess the flexibility to visually acknowledge individual humans and to transmit info concerning "bad" humans by squawking.[45] Crows seem to point out appreciation to humans by presenting them with gifts.