Arizona Bald Eagle Management Program

Demographic Studies

To assess the health of the bald eagle in Arizona, biologists started placing U.S. Fish and Wildlife Service bands on nestlings in the late 1970s and early 1980s. Later, biologists used colored visual identification bands to document replacement of breeding adults, natal origin, age of first breeding, and mortality. The Arizona Game and Fish Department and the U.S. Fish and Wildlife Service have continued these efforts since 1991.

Demographic information helps biologists identify factors affecting population viability. Five tasks are necessary to assess population demographics: 1) nestlings must be banded and their sex determined; 2) breeding adults must be identified; 3) statewide productivity data must be collected; 4) mortality sources in each age class need to be identified; and, 5) catostrophic events must be assessed. While it is ideal to accomplish the above tasks yearly with 100 percent success, often logistics and time constraints impede the efforts.