Bird conservation


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. For birds having gone extinct in modern times, see List of extinct birds.

Historical Analysis

Prehistory to Early History

Since the Late Pleistocene period, it is estimated that 1,430 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.

Pre-Industrial Era into the Industrial Era

Before the Industrial Revolution, 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 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.
File:1863 17 26 Parakeet.jpg|alt=An illustration of a flock of Carolina parakeets by John James Audubon|thumb|Illustration of Carolina parakeets by John James Audubon
In North America, the Carolina parakeet one of the few parrots indigenous to the United States, suffered from Industrial era deforestation and hunting, which helped destroy wild populations. The species' final extinction came in the early 20th century, though causes remain unclear.
Similarly, the passenger pigeon 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. 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.

Advocacy in the 20th Century

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.
The 1960s were a particularly pivotal era in favor of bird conservation. The publication of Rachel Carson’s Silent Spring aided in exposing widespread dangers of pesticide use, particularly DDT, on bird populations. Her groundbreaking work demonstrated how DDT led to the thinning of eggshells in species like the bald eagle and peregrine falcon, resulting in reproductive failures. Carson’s book ignited a broader environmental movement, leading to significant policy changes, and the eventual DDT ban. The Environmental Protection Agency enforced a generalized ban on DDT pesticides in 1972. Bald eagles made a famous comeback during the “dirty sixties” thanks to this ban, along with the brown pelican and peregrine falcon.
By the 1980s, the global conservation movement gained further momentum. Organizations like BirdLife International played an increasingly vital role in establishing international frameworks for bird protection. This included efforts to protect critical habitats, such as wetland areas, and to monitor at-risk species. Additionally, the International Union for Conservation of Nature developed the Red List of Threatened Species, which continues to serve as an important tool for identifying and tracking species at risk of extinction, including many bird species.

Threats to birds

Habitat loss

The most critical threat facing threatened birds is the destruction and fragmentation of habitat. The loss of forests, plains and other natural systems into agriculture, mines, and urban developments, the draining of swamps and other wetlands, and logging reduce potential habitat for many species. In addition the remaining patches of habitat are often too small or fragmented by the construction of roads or other such barriers that cause populations in these fragmented islands to become vulnerable to localized extinction. In addition many forest species show limited abilities to disperse and occupy new forest fragments. The loss of tropical rainforest is the most pressing problem, as these forests hold the highest number of species yet are being destroyed quickly. Habitat loss has been implicated in a number of extinctions, including the ivory-billed woodpecker , Bachman's warbler, and the dusky seaside sparrow.

Climate change

is a catalyst for the worrying downward trend of bird populations globally. The speed of human-caused climate change is currently unprecedented, leading bird species into continuously unadaptable circumstances. The American Bird Conservancy states there is a clear and direct comparison between bird population decline and climate change, stating that “arming temperatures are changing where birds live, the timing of their migration patterns and egg laying, and even the sizes and shapes of their bodies.”

Direct impacts

It has been observed that most North American bird species have been recognized over the prior few decades to have shifted their breeding ranges irregularly due to climate change. Migratory birds are more prone to the effects of climate change, leading to shifts in time migratory patterns. It is predicted in the coming years that mountainous birds will even lose suitable migratory habitats due to rising temperatures at higher elevations. On top of these migratory shifts, global warming has been predicted to be changing size and wing length proportionally in all bird species. It is presumed that with rising temperatures, smaller birds maintain better competitive fitness thanks to their easier heat dispersal compared to their larger counterparts within the same species.

Indirect impacts

Indirect impacts of climate change on birds include increased drought and fires, rising-sea levels, increased disease, phenological mismatch, and uncommon interactions between species. Increase in drought leads to increased fires, destroying nesting ground and fragmenting specifically sagebrush ecosystems. Rise in sea-levels provides similar altercations for marsh-nesting birds. Nesting sites disappear as sea-levels rise, eliminating habitats for nesting parents and young to continue species. Phenological mismatch occurs due to rising temperatures shifting migratory timeframes but not quickly enough, altering the life cycle events in interacting species at different rates.