Bird extinctions have occurred throughout history, with over 150 species having gone extinct since the year 1500. The primary causes of bird extinction include:
- Habitat loss and degradation
- Invasive species
- Overexploitation
- Pollution
- Climate change
Habitat loss, invasive species, and overexploitation have historically been the leading threats to birds. More recently, climate change has emerged as a major driver of extinctions and population declines. Understanding the key threats to birds can help guide conservation efforts aimed at protecting species at risk of extinction.
What is extinction?
Extinction refers to the complete disappearance of a species from the planet. This occurs when there are no more living individuals of that species anywhere in the world. Once a species goes extinct, it is gone from the Earth forever unless it is “de-extincted” through advanced cloning technology.
For a species to go extinct, typically every single individual must die. Even if there are no more individuals in the wild, a species is not officially extinct as long as some individuals survive in captivity. However, species that only exist in captivity and no longer have wild populations are functionally extinct.
There are different types of extinction:
- Local extinction occurs when a species disappears from a particular geographic area, but continues to exist elsewhere in the world.
- Global extinction is when a species disappears from the entire planet.
- Ecological extinction is when a species declines to such low numbers that it no longer plays its typical ecological role, even if it is not completely gone.
This article focuses on the global extinction of birds and the factors that have caused species to disappear completely from the Earth. Local and ecological extinctions are also contributing to declines in bird biodiversity worldwide.
How many bird species have gone extinct?
Determining exact numbers of extinct species is challenging. However, based on historical records, at least 150 bird species are believed to have gone extinct globally since the year 1500. This represents about 1.5% of the approximately 10,000 known species of birds.
Some of the major extinct bird species include:
- Passenger Pigeon: Once extremely abundant in North America, hunting and habitat loss drove this pigeon extinct by 1914.
- Carolina Parakeet: This unique parrot inhabited forests in the eastern United States before going extinct in the early 1900s due to hunting and habitat loss.
- Great Auk: This large flightless seabird bred in the North Atlantic before being hunted to extinction by the mid-1800s.
- Dodo: This famous flightless bird inhabited Mauritius before going extinct in the late 1600s due to hunting and invasive species.
- Hawaiian Oo: Hawaii was once home to many unique honeycreepers, several of which went extinct following Polynesian settlement of the islands.
These are just a few examples of the many bird species that have been lost over recent centuries. Many extinctions went unnoticed, and some species disappeared before they were even scientifically described. The extinction crisis has accelerated in recent decades, putting many additional bird species at risk.
When did most bird extinctions occur?
The timing of bird extinctions has not been constant over the past several centuries. Instead, extinctions have occurred more frequently during certain time periods:
- Early 1800s: Many bird species on remote islands went extinct after being over-hunted for food or feathers, or due to invasive species like rats.
- Late 1800s: Hunting for the millinery trade caused the extinction of several mainland birds including the Passenger Pigeon and Carolina Parakeet in North America.
- Early 1900s: Habitat loss drove additional extinctions, including forest birds like the Ivory-billed Woodpecker.
- Mid-late 1900s: Toxic pesticides like DDT caused severe declines, including the near-extinction of birds of prey like the Bald Eagle and Peregrine Falcon.
- Present: Habitat loss, invasive species, hunting, and climate change are driving a new wave of extinctions, especially on islands.
The early 1800s and late 1800s stand out as having particularly high numbers of bird extinctions. However, the extinction risk remains high today for many endangered bird species around the world. Preventing future extinctions requires addressing the key threats currently facing birds.
What causes bird extinctions?
There are five primary factors that have caused bird species to go extinct:
Habitat Loss and Degradation
The destruction of forest, grassland, wetland, and other natural ecosystems to make way for human activities is the leading cause of bird extinctions worldwide. Habitat loss removes the areas that birds need to survive. It fragments remaining habitats, leaving populations isolated and vulnerable.
Agriculture, logging, infrastructure development, and urban expansion all contribute to habitat loss. Island species are especially vulnerable, as habitat loss can rapidly make the entire island unsuitable. Even small habitat changes can cause extinctions of species that have specialized habitat requirements.
Invasive Species
Invasive predators are the second greatest threat to birds globally. Species like rats, cats, and snakes have caused numerous bird extinctions, especially on islands. These predators are not native, and island birds did not evolve defenses against them.
Other invasive species like grazers, parasites, and diseases also impact native bird populations. Birds that evolved in isolation on remote islands lack resistance. Invasive plants can alter habitat structure, depriving native birds of nesting sites or food sources.
Overexploitation
Hunting and trapping have driven many bird species extinct, including the Great Auk, Passenger Pigeon, and Carolina Parakeet. Birds are hunted for food, feathers, or simply out of cruelty. Overcollection of eggs and chicks also contributes to extinctions.
While most bird hunting now has regulations, poaching continues to threaten endangered species. Other forms of exploitation like illegal wildlife trade also put pressure on rare birds.
Pollution
Environmental contaminants have caused bird population declines and extinctions. Pesticides accumulate in food chains, poisoning raptors and other bird species. The insecticide DDT caused severe eggshell thinning, wiping out several predatory bird species until it was banned.
Oil spills are also extremely harmful to seabirds. Other toxins in the environment including lead, mercury, and plastics impact bird health and reproduction. Even noise and light pollution can harm birds by interfering with their navigation and migration.
Climate Change
Rising global temperatures are becoming a major extinction threat as climate patterns shift faster than some birds can adapt. Impacts include:
- Changes in the timing of food availability
- Loss of coastal nesting habitat due to sea level rise
- Increasing frequency of extreme weather events
- Drying out of wetland habitats
- Shifting ranges of competitors and disease
Birds with small geographic ranges, specialized diets, or unusual migration patterns are most vulnerable to climate-related extinction. Protecting habitats and reducing other threats can help increase their resilience.
Why do bird extinctions matter?
Bird extinctions should concern everyone because they indicate collapsing ecosystems and loss of biodiversity. Some specific reasons bird extinctions matter include:
- Ecological effects: Birds play key roles in ecosystems including pollination, seed dispersal, and pest control. Their loss damages ecosystems.
- Environmental health: Birds are indicators of environmental problems like pollution and habitat change. Their declines signal broader issues.
- Economic impacts: Birds provide pest control, pollination, and recreation worth billions of dollars annually.
- Cultural loss: Symbolic birds like the Bald Eagle hold meaning in societies. Birdwatching generates huge tourism revenues.
- Ethical concerns: Many believe biodiversity has intrinsic value, making any species extinction troubling.
Preventing further loss of birds requires taking their conservation seriously. Birds tell us about the health of the environments we all depend on. Allowing more extinctions risks irreversible ecological damage and loss of resilience to future changes.
Recent extinctions and near-extinctions
While the main wave of bird extinctions occurred in the 1800s and early 1900s, risks have accelerated again in recent decades. Some examples of troubling recent declines and extinctions include:
| Species | Status | Factors |
|---|---|---|
| Spix’s Macaw | Extinct in the wild since 2000 | Habitat loss, poaching |
| Hawaiian Crow | Fewer than 150 individuals left | Habitat loss, invasive species |
| Northern Spotted Owl | Populations declining 2.9% per year | Habitat loss |
| Royal Penguin | Population dropped 70% in 30 years | Climate change |
These examples illustrate how diverse threats are continuing to push species toward extinction. Aggressive conservation action is needed to protect birds like these that remain on the brink.
Which bird families are most threatened?
Some taxonomic groups of birds are more vulnerable to extinction than others:
- Parrots: Over 1/3 of parrot species are threatened, primarily by habitat loss and trapping for the pet trade.
- Hawaiian honeycreepers: Two-thirds of these colorful forest birds have gone extinct due to habitat loss, disease, and invasive species.
- Seabirds: These ocean-foraging birds face threats on their breeding colonies from invasive species as well as pollution at sea.
- Wetland birds: Marsh birds have extremely specialized habitat needs, putting them at high risk as wetlands are drained and degraded.
- Endemic island birds: Species with tiny ranges on isolated islands are vulnerable to any change in habitat or introduction of predators.
However, no group of birds is completely immune to extinction risk. Even widespread generalist species are declining from threats like house cats, glass buildings, and vehicle collisions. Targeted conservation helps high-risk groups, but addressing systematic threats is needed to protect all birds.
How can future bird extinctions be prevented?
More bird extinctions can be avoided through more thorough implementation of key conservation strategies:
- Habitat protection: Preserve areas of natural habitat large enough to support viable bird populations and ecosystem functions.
- Invasive species control: Rapidly respond to eradicate new invasive species. On islands, work to fully remove established invasives like rats and cats.
- Wildlife-friendly practices: Promote agricultural, forestry, fishing, and other practices that minimize harm to birds and ecosystems.
- Pollution reduction: Implement stronger air, water, and soil pollution controls, including bans on highly harmful chemicals.
- Climate change mitigation: Shift energy systems away from fossil fuels to limit the severity of climate change impacts on birds.
- Community engagement: Provide education on birds and threats to generate public support for conservation.
Well-resourced, coordinated efforts across these interventions are needed to prevent the extinction of threatened birds and reverse ongoing population declines. Saving birds ultimately requires sustaining the healthy, biodiverse ecosystems we all depend upon.
Conclusion
Bird extinctions over the past centuries have been caused mainly by human activities like habitat destruction, overhunting, pollution, and the introduction of invasive species. These threats have led to the global extinction of over 150 bird species total, with certain groups of birds especially hard hit. Habitat loss and invasive species continue to be the primary drivers of extinctions and declines, along with climate change which is an emerging extinction threat. Preventing further loss of bird diversity requires targeted conservation action across habitats and sustained investment to address systematic pressures on wildlife and ecosystems. The fate of the world’s birds is intertwined with our own, so protecting them is key for creating conditions that allow both birds and people to thrive.
