Bird conservation is a field in the science of conservation biology related to threatened birds. Bird conservation efforts aim to protect species and mitigate the decline of threatened bird population numbers. According to Worldwatch Institute, many bird populations are currently declining worldwide, with 1,200 species facing extinction in the next century. Current estimates imply a total of nearly 11,000 extant species, suggesting that 11.6% of all bird species, a near ratio of one in nine birds, have gone extinct over the last 126,000 years of human history. The biggest cited reason surrounds habitat loss. Other threats include overhunting, accidental mortality due to structural collisions, long-line fishing bycatch, pollution, competition and predation by pet cats, oil spills and pesticide use and climate change. Governments, along with numerous conservation charities, work to protect birds in various ways, including legislation, preserving and restoring bird habitat, and establishing captive populations for reintroductions.

See Late Quaternary prehistoric birds for birds which disappeared in prehistoric and early historic times, usually due to human activity (i.e., starting with the Upper Paleolithic Revolution). For birds having gone extinct in modern times (since 1500), see List of extinct birds.

Since the Late Pleistocene period, it is estimated that 1,430 (95% credible interval: 1327–1544) bird extinctions have occurred. Human activity has been directly attributed to almost all bird species extinctions, specifically prehistoric and early historical species. During the Upper Paleolithic period, human societies began spreading across the globe, leading to the overhunting of species and the introduction of invasive species to new environments. A particularly significant period of extinction occurred when humans colonized the islands of Melanesia, Polynesia, and Micronesia around 4,000 years ago. According to a study published in Proceedings of the National Academy of Sciences, early Polynesian settlers are often credited with contributing to the extinction of over 1,000 bird species during this time, majority of which were non-passerine land birds.

Before the Industrial Revolution (1750-1850), most bird species were not yet heavily impacted by habitat loss or climate change. However, overexploitation through hunting, bird collecting, as well as the introduction of invasive species became significant threats. Industrialization marked a turning point in the relationship between humans and birds. The technological growth, urban expansion, and increased emissions from industrial activity caused widespread habitat destruction and altered ecosystems. In the United Kingdom, species such as the white-tailed eagle (Haliaeetus albicilla) and cranes, for example, were recognized as more abundant before industrialization began. By the 19th century, the advent of industrial-scale hunting and urban sprawl had put pressure on many bird populations.

In North America, the Carolina parakeet (Conuropsis carolinensis) one of the few parrots indigenous to the United States, suffered from Industrial era deforestation and hunting (both for its colorful feathers, and because the birds were thought to feed on crops), which helped destroy wild populations. The species' final extinction came in the early 20th century, though causes remain unclear.

Similarly, the passenger pigeon (Ectopistes migratorius) once one of the most populous bird species in North America, was driven to extinction in the early 20th century due to relentless hunting and habitat loss. This extinction served as a stark reminder of the fragility of bird populations in the face of human intervention. The loss of such a previously abundant species helped catalyze the first major bird conservation efforts in the United States. Following the assumed extinction of passenger pigeons, Theodore Roosevelt claimed to have witnessed a small flock of the birds at his family name’s rural cabin in Virginia some 25 years after their extinction (March 24, 1900). Following this sighting, Theodore recognized the severity of the loss of this once abundant species and initiated strengthened bird advocacy legislation during his presidency in 1907. The establishment of the first Federal Bird Reserve on Pelican Island in Florida can be attributed to this sighting made by President Roosevelt.

The early 20th century saw the rise of formal conservation efforts. The National Audubon Society, founded in 1905, played a key role in raising awareness about the rapid decline of bird populations, specifically in response to the exploitation of birds for the feather trade. The organization's efforts were influential in propelling early legal protections for birds. A significant achievement in favor of bird protection was the passage of the Migratory Bird Treaty Act of 1918. This act provided international protection for migratory bird species between the United States, Canada, Mexico, Japan, and Russia.

From the 1920s to 1950s, bird advocacy gained further strength. In 1934, the Duck Stamp Act was passed. It sought to fund the protection of wetlands using hunter fees. Additionally, during the Great Depression, New Deal programs including the Civilian Conservation Corps preserved wildlife refuges, providing birds a thriving environment for bird species. Birdwatching gained popularity within this timeframe, too, in large part thanks to Roger Tory Peterson’s groundbreaking field guides. Finally, Rachel Carson's early works began to clarify the relationship between healthy bird populations and a healthy planet. All of these factors laid more solid groundwork for the continuation of advocacy for birds.