Direct human-caused mortality of birds: improving quantification of magnitude and assessment
of population impact
Scott R Loss1*, Tom Will2, and Peter P Marra1
Hundreds of millions to greater than one billion North American birds are directly killed each year by human
stressors, including collisions with man-made structures, predation by feral and pet cats, intentional and accidental
poisoning, and pollution. Because these causes of mortality are increasingly abundant and because some result in
large bird die-offs, they have received both increased scientific attention and general media coverage. However,
quantifying bird mortality remains imprecise and methods to assess whether these losses cause important biological
impacts remain underdeveloped. If local mortality studies followed rigorous design and sampling schemes, allowing
comparison of data and scaling up of mortality estimates to broad regions, this could lead to improved analyses.
Several analytical techniques – including hierarchical and full life-cycle population models – show potential for
improving quantification of anthropogenic mortality of birds and inference of population-level effects. Results
arising from improved study designs and analytical techniques will more effectively inform decision making about
policies and regulations aimed at reducing avian mortality and minimizing population impacts.
Front Ecol Environ 2012; doi:10.1890/110251