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State of the Birds Report

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Bird Mortality



Habitat loss is by far the greatest cause of bird population declines. Humans also kill billions of birds in the U.S. annually through more direct actions, such as allowing outdoor cats to prey upon birds. Canadian bird mortality estimates show remarkably similar patterns. Data-driven assessments of how different human-caused sources of bird mortality contribute to population declines are essential for developing strategic conservation objectives and science-based policies.

Reducing or eliminating direct sources of mortality could save millions, if not billions, of birds annually. The best ways to reduce bird mortality include:

Cats: Keeping pet cats indoors and implementing policies to eliminate feral cat colonies.

Collisions: Following bird-friendly window practices, reducing night lighting in and on tall buildings, warning auto drivers in high collision areas, installing flashing rather than steady-burning lights on communication towers, and locating wind turbines away from areas of high bird concentrations (especially areas that pose threats to particular species such as eagles).

Chemicals: Limiting the broadcast spraying of pesticides and insecticides and introducing integrated pest management practices (which
reduce or eliminate chemical applications) in agricultural areas.

Bar chart based on independent assessments of direct human-caused mortality in the United States and Canada. This data is adapted from Loss SR, Will T, Marra PP. Direct human-caused mortality of birds. Annual Review of Ecology, Evolution, and Systematics In prep



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