Human Caused Mortality
As we become more aware and sensitive to our environment, direct deaths from human mortality decreases. Most human mortality is caused by environmental contamination and habitat destruction. We almost lost the peregrine in continental US due to DDT poisoning. Although we have banned the use of DDT in the United States, the peregrine migrates to Mexico ,Central and South America where levels are still high. As an apex species in our food chain, feeding almost entirely on birds, the peregrine is one of the most important species that serve as indicators of our environmental health. Most known mortality during our 16 year study period was caused by peregrines colliding with motorized vehicles.
West Nile Virus and other avian diseases may ultimately pose the greatest threat to the peregrine falcon. Continued monitoring for diseases is necessary to insure the health of our wild populations.
Human caused mortality of young golden eagle. Photographers placed a blind directly in front of eyrie and the adults would not enter the eyrie to feed the young.
The Great Gray Owl and the Great Horned Owl, two of Montana’s largest owls, prey on both adult and young peregrine falcons. The owls hunt during low-light conditions when the peregrine are perched and susceptible to predation.
Golden eagles are one of the most common raptors found in Montana. Eagles establish territories on and around many of the cliffs that could be used by peregrine falcons. Like the owls, they prey on the young peregrines as they fledge from the nesting ledges.
Montana Bald Eagle populations have increased dramatically since DDT was banned. The bald eagle nests in trees but frequented the river corridors where peregrines nest. Bald eagles probably prey on the newly fledged young peregrine falcons.