Monday, April 8, 2019


Birds – our winged friends are important components of our life cycle. They are also called as “Aves" and "Avifauna". They are a group of endothermic vertebrates, with feathers, a beak with no teeth, laying hard-shelled eggs, with a high metabolic rate, a four-chambered heart and a lightweight but strong skeleton. Birds live worldwide and range in size from 5 cm bee humming bird to the 2.75 m ostrich. More than half of these are passerines, known as perching birds or as song birds.
Birds are the last surviving dinosaurs according to the fossil records, having evolved from feathered ancestors. Birds have wings which are more or less developed depending on the species; wings evolving from forelimbs, giving most birds the ability to fly. There are some flightless birds, including ratitespenguins and diverse endemic island species. The digestive and respiratory systems of birds are uniquely adapted for flight. Some bird species of aquatic environment have evolved for swimming. Birds played an important part in the inception of Darwin's theory of evolution by natural selection.
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Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls and bird songs, participating in social behaviors like cooperative breeding and hunting, flocking and mobbing of predators. A vast majority of bird species are socially monogamous, either for one breeding season at a time, sometimes for years, but rarely for life. Birds produce offsprings by laying eggs fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, which do not produce offspring.
Birds occupy a wide range of ecological positions. While some birds are generalists, others are highly specialized in their habitat or food requirements. Within a single habitat, such as a forest, the niches occupied by different species of birds vary, with some species feeding in the forest canopy, others beneath the canopy, still others on the forest floor. Forest birds may be insectivoresfrugivores, and nectarivores. Aquatic birds generally feed by fishing, plant eating, and piracy or kleptoparasitism. Birds of prey specialize in hunting mammals or other birds, while vultures are specialized scavengersAvivores are animals that are specialized at preying on birds.
Many species of birds are economically important. Domesticated and undomesticated birds (poultry and game) are important sources of eggs, meat and feathers. Song birdsparrots and other species are popular as petsGuano (bird excrement) is harvested for use as a fertilizer. Recreational bird watching is an important part of the ecotourism industry. Some nectar-feeding birds are important pollinators, and many frugivores play a key role in seed dispersal. Plants and pollinating birds often co-evolve and in some cases a flower's primary pollinator is the only species capable of reaching its nectar.
Birds are often important to island ecology. Birds have frequently reached islands that mammals have not; on those islands, birds may fulfill ecological roles typically played by larger animals. Nesting seabirds may also affect the ecology of islands and surrounding seas, principally through the concentration of large quantities of guano, which may enrich the local soil and the surrounding seas.
A wide variety of avian ecology field methods, including counts, nest monitoring, capturing and marking, are used for researching avian ecology.
Since birds are highly visible and common animals, humans have had a relationship with them since ages. These relationships may be mutualistic, like the cooperative honey-gathering among honey guides and African peoples such as the Borana. Other times, they may be commensal, as when species such as the house sparrow have benefited from human activities. Several bird species have become commercially significant agricultural pests and some pose an aviation hazard. Human activities can be detrimental, and have threatened numerous bird species with extinction (huntingavian lead poisoningpesticidesroadkill, and predation by petcats and dogs are common sources of death for birds). Birds can act as vectors for spreading diseases like psittacosissalmonellosiscampylobacteriosis, mycobacteriosis (avian tuberculosis), avian influenza (bird flu), giardiasis and cryptosporidiosis over long distances. Some of these are zoonotic diseases that can also be transmitted to humans. Domesticated birds raised for meat and eggs, called poultry, are the largest source of animal protein eaten by humans. Many species of birds are hunted for meat. Bird hunting is primarily a recreational activity except in extremely undeveloped areas.
Other commercially valuable products from birds include feathers (especially the down of geese and ducks), which are used as insulation in clothing and bedding, and seabird feces (guano), which is a valuable source of phosphorus and nitrogen. Birds have been domesticated by humans both as pets and for practical purposes. Colorful birds, such as parrots and mynas are bred in captivity or kept as pets, a practice that has led to the illegal trafficking of some endangered speciesFalcons and cormorants have long been used for hunting and fishing, respectively. Pigeons were used as messengers in olden times. Such activities are more common either as hobbies, for entertainment and tourism or for sports such as pigeon racing, today.
Amateur bird enthusiasts (called birdwatchers, twitchers or birders) number in the millions. Many homeowners erect bird feeders near their homes to attract various species. 
Birds prominently figure throughout human culture.
Birds play prominent and diverse roles in folklore, religion, and popular culture. In religion, birds may serve as either messengers or priests and leaders for a deity, as chiefs or as attendants.  In several civilizations of ancient Italy and Roman religion, priests watched their activities to foretell events. They may also serve as religious symbols. Birds have perceived as Mother Earth or as monsters.
Birds have been featured in culture and art since prehistoric times, when they were represented in early cave paintings. Birds were later used in religious or symbolic art and design, such as the magnificent Peacock Throne of the Mughal and Persian emperors.  Birds are important figures in poetry; for example nightingales.
Perceptions of various bird species often vary across cultures. Owls are associated with bad luck, witchcraft and death in parts of Africa but are regarded as wise across much of Europe. Birds are depicted in the process of transgressing boundaries between earthly and underground spiritual realms.
About 120–130 species have become extinct due to human activity since the 17th century and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Most common example is of common sparrows which are almost extinct, probably as a result of particular electronic waves which seem to harm them.
Though human activities have also allowed the expansion of a few species, such as the barn swallow and European starling, they have caused population decreases or extinction in many other species. Many bird populations are declining worldwide, with 1,227 species listed as threatened by Bird Life International and the IUCNin 2009.
The most commonly cited human threat to birds is habitat loss. Other threats include overhunting, accidental mortality due to structural collisions or long-line fishing by catch, pollution (including oil spills and pesticide use), competition and predation from nonnative invasive species and climate change.
Governments and conservation groups work to protect birds, either by passing laws that preserve and restore bird habitat or by establishing captive populations for reintroductions. Such projects have produced some successes; one study estimated that conservation efforts saved 16 species of bird that would otherwise have gone extinct between 1994 and 2004. We all must protect, feed and preserve birds in whatever way we can, as they are an important part of our life cycle, which may get disturbed by their extinction. 

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Dr Mrs Jaya Vikas Kurhekar
Green Blogger