Migratory birds face numerous threats throughout their annual cycles from both natural and human-caused sources. The U.S Fish & Wildlife Service is working with governments, conservation organizations, industry, and the public to reduce threats across the North American landscape to preserve our birds for future generations. There also many easy ways anyone in the general public can help protect birds around your communities.
What Are the Threats to Birds?
Many of the 1,027 species of birds protected under the Migratory Bird Treaty Act are experiencing population declines due to increased threats across the landscape. Of those 1,027 species, 92 bird species are listed as either threatened or endangered under the U.S. Endangered Species Act. An additional 274 species are listed as Birds of Conservation Concern, in one or more geographic scales (e.g., local, regional, or national). For more information about bird declines in the U.S., visit the State of the Birds webpage.
Both natural and human-caused sources of bird mortality contribute cumulative or combined effects to declining bird populations. Millions of acres of bird habitat are lost or degraded every year due to development, agriculture, and forestry practices. These rapidly accelerating impacts can be mitigated only through habitat restoration and protection. In addition, millions of birds are directly killed by human-caused sources such as collisions with man-made structures. Death from natural causes is also common sources of mortality.
Natural and human-caused mortality impacts are exacerbated by the landscape alterations resulting from a changing climate. Birds in every habitat will be affected by natural and human-caused sources, so conserving migratory bird populations requires a multi-faceted, coordinated approach by governments, conservation organizations, industry, and the general public.
How Many Birds are Killed?
True estimates of mortality are difficult to determine. However, there are recent studies that have synthesized the best available data to estimated ranges of mortality to bird populations in North America from some of the most common, human-caused sources of bird mortality. These are listed in the table below. This list addresses only human-caused sources, not natural sources. There are also many additional human-caused threats to birds, both direct (causing immediate injury/death) and indirect (causing delayed negative effects to health or productivity) that are not on this list because the extent of their impact is either not currently well researched or easily quantified. For instance, habitat loss is thought to pose by far the greatest threat to birds, both directly and indirectly, however, its overall impact on bird populations is very difficult to directly assess. Other common human-caused and natural threats to birds that are known, but not listed below include various entanglement and entrapment threats (e.g., open pipes and nets); predation by other animals besides cats, including humans (e.g., poaching); weather events; starvation; and disease.
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