Relationship with humans

Two rows of cages in a dark barn with many white chickens in each cage
Industrial farming of chickens

Since birds are highly visible and common animals, humans have had a relationship with them since the dawn of man.[169] Sometimes, these relationships are mutualistic, like the cooperative honey-gathering among honeyguides and African peoples such as the Borana.[170] Other times, they may be commensal, as when species such as the House Sparrow[171] have benefited from human activities. Several bird species have become commercially significant agricultural pests,[172] and some pose an aviation hazard.[173] Human activities can also be detrimental, and have threatened numerous bird species with extinction (hunting, avian lead poisoning, pesticides, roadkill, and predation by pet cats and dogs are common sources of death for birds).

Birds can act as vectors for spreading diseases such as psittacosis, salmonellosis, campylobacteriosis, 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.[174]
Economic importance

Domesticated birds raised for meat and eggs, called poultry, are the largest source of animal protein eaten by humans; in 2003, 76 million tons of poultry and 61 million tons of eggs were produced worldwide.[175] Chickens account for much of human poultry consumption, though turkeys, ducks, and geese are also relatively common. Many species of birds are also hunted for meat. Bird hunting is primarily a recreational activity except in extremely undeveloped areas. The most important birds hunted in North and South America are waterfowl; other widely hunted birds include pheasants, wild turkeys, quail, doves, partridge, grouse, snipe, and woodcock.[176] Muttonbirding is also popular in Australia and New Zealand.[177] Though some hunting, such as that of muttonbirds, may be sustainable, hunting has led to the extinction or endangerment of dozens of species.[178]
Illustration of fisherman on raft with pole for punting and numerous black birds on raft
The use of cormorants by Asian fishermen is in steep decline but survives in some areas as a tourist attraction.

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. The War of the Pacific, sometimes called the Guano War, was fought in part over the control of guano deposits.[179]

Birds have been domesticated by humans both as pets and for practical purposes. Colourful 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 species.[180] Falcons and cormorants have long been used for hunting and fishing, respectively. Messenger pigeons, used since at least 1 AD, remained important as recently as World War II. Today, such activities are more common either as hobbies, for entertainment and tourism,[181] or for sports such as pigeon racing.

Amateur bird enthusiasts (called birdwatchers, twitchers or, more commonly, birders) number in the millions.[182] Many homeowners erect bird feeders near their homes to attract various species. Bird feeding has grown into a multimillion dollar industry; for example, an estimated 75% of households in Britain provide food for birds at some point during the winter.[183]