What are some of the major threats to birds?

Birds face many threats to their survival in the wild. Like all animals, they are totally dependent on their environment for existence and are very sensitive to changes in the ecosystems. Many populations of bird species are on the decline. To place the blame for this decline on a single factor would be wrong. There are combinations of causes which need to be addressed in order to turn the trend of demise. Below is a summary of a number of these threats and some links to further resources.

One cause of the decline in populations is climate change caused by global warming. As temperatures rise, birds are thrown from their migration cycle; when birds reach their destinations they rely on certain foods to live through the season. Breeding success in some species, such as insect-eating songbirds, could be jeopardized due to mismatch between the peak of availability of food and hatching of chicks. Climate change leads to changes and shifts in habitats, which causes re-distribution of birds, too. Some species are threatened by nearly complete loss of their habitats.

• Climate change will soon threaten many more species with extinction (BirdLife International)
• Climate change is already impacting biodiversity (BirdLife International)

Alien invasive species have damaged bird populations in some parts of the world, particularly those that occupy islands. A rise in global trade and travel over the past century has led to acceleration in the introduction of exotic species. Exotic species - including snakes, rats, cats, plants, and insects - now menace a quarter of globally threatened bird species.

• Alien invasive species, including diseases, are spreading (BirdLife International)

By far the largest threat to birds is the loss of habitat. Deforestation, the draining of wetlands, planting of non-native trees, the loss of areas to urban developments and intensive agriculture are major threats to birds.  Numbers of many species are in serious decline as a result of habitat loss and these losses are particularly serious on islands, where bird populations are often small and very fragile.

• Habitat destruction is the largest of the many threats to biodiversity (BirdLife International)
• Expanding agriculture destroys more habitat than any other factor (BirdLife International)
• Why conserve species? (RSPB)

Oil spills constitute a major threat to birds too, particularly for those that spend a lot of time on the surface of the water such as loons, alcids and waterfowl. But also other migratory birds are at risk; having just started their annual migration, many birds pass through contaminated sites which are important staging areas for them. Large scale oil spills often kill thousands of birds.

• Oil spills and pollution (RSPB)

Unsustainable harvest and poorly enforced laws lead to the killing of millions of birds around the world. Especially across the tropics commercial harvest for trade is decimating many bird populations and may be one of the gravest threats presently facing birds in rainforests.

Ill-advised wind energy development can have a negative impact on bird populations as well. Birds often collide with power lines leading to wind farms, masts, poles and wind turbines. For example wind turbines have caused a number of deaths of Europe's largest eagle species. Furthermore reduced breeding productivity or reduced survival may result if birds are displaced from preferred habitat and are unable to find suitable alternatives.

• Bulgarian windfarms threaten migratory birds (BirdLife International)
• Wind farm causes eagle deaths (BirdLife International)

Present demand for ethanol is increasing corn prices and expanding corn acreage, and that in turn decreases the area available for wildlife. In the future, biofuels may be taken from a wider variety of plant sources and conditions for wildlife could be enhanced. In any case, biofuels threaten to drive large and possibly rapid changes in land use. Converting large amounts of cropland for biofuel production will result in loss of high-value bird habitats such as wetlands, wet meadows, grasslands and scrub.

• BirdLife urges caution in biofuel drive (BirdLife International)

Plastic waste is another serious risk to bird populations. Sea birds are mistaking plastic pellets for fish eggs, small crabs and other prey, sometimes even feeding the deadly pellets to their young. Despite the fact that only 0.05 percent of plastic pieces from surface waters are pellets, they comprise about 70 percent of the plastic eaten by sea birds. These small plastic particles have been found in the stomachs of 63 of the world’s 250 species of sea birds.

• The trash vortex (Greenpeace)