The birds congregate in the NCA not because it is a protected area, but because it is an ideal place for raptors to live. The uplift of air from the Snake River Canyon makes flying and gliding (sorry) a breeze for the birds, and the uplands above the canyon rim provide habitat for ground squirrels and other critters the birds consider lunch.
Morley Nelson figured that out when he first saw the canyon in the late 1940s. He had developed a love for raptors—especially peregrine falcons—growing up on a farm in North Dakota. When he moved to Idaho, following a WWII stint with the famous Tenth Mountain Division, he went out to the Snake River Canyon to see if he could find some raptors. He found a few. There are typically about 800 pairs of hawks, eagles, owls, and falcons that nest there each spring. It’s the greatest concentration of nesting raptors in North America, and probably the world.
Nelson became evangelical about the birds and their Snake River Canyon habitat. He worked on films about the birds with Walt Disney, Paramount Pictures, the Public Broadcasting System, and others. His passion for the birds was contagious, and through his efforts public understanding of their role in the natural world was greatly enhanced.
Morley Nelson convinced Secretary of the Interior Rogers Morton to establish the Snake River Birds of Prey Natural area in 1971, and an expansion of the area by Interior Secretary Cecil Andrus in 1980. Then in 1993, US Representative Larry LaRocco led an effort in Congress to designate some 485,000 acres as a National Conservation Area.
It was also Nelson who led the effort to convince the Peregrine Fund to relocate to Boise and build the World Center for Birds of Prey south of town.
While those efforts were going on, Nelson was also doing pioneer work on an effort to save raptors from power line electrocution. He worked with the Edison Electric Institute and Idaho Power to study how raptors used those manmade perches known as power poles. Through those efforts poles are now designed to minimize electrocution and even provide safe nesting areas for the birds.
When Morley Nelson passed away in 2005 he had unquestionably done more to save and protect raptors than any other single person.
For more on Morley Nelson, see his biography, Cool North Wind, written by Steve Steubner.