Bald Eagles: Breeding Versus Wintering in the Verde Valley

Most people don’t realize that Arizona hosts two different populations of bald eagles – those that are wintering in Arizona but will migrate to the northern portions of North America to breed and those bald eagles that are a small subset of southwestern eagles that reside in Arizona year-round. Wintering bald eagles arrive in Arizona around the second week of October where they occur along streams and around lakes to forage on fish and waterfowl and along highways where they opportunistically feed on road-killed wildlife. Their numbers peak in February and they stay until around the third week of April.  Then they leave the southwest to return to their breeding grounds in the northwestern United States, Alaska, and Canada. By the time wintering eagles leave our state to start courtship in their breeding grounds in northern latitudes, our resident bald eagles already have babies in the nest!

Arizona is home to the entire known population of desert nesting bald eagles Fin the United States. This southwestern population of bald eagles nests primarily along the Salt and Verde Rivers in central Arizona. Currently, a total of 73 occupied bald eagle breeding areas exist in the state. Roughly a quarter of occupied breeding areas occur along the Verde River. Breeding bald eagles can be observed in their breeding areas from late November through June. Our resident bald eagles have adapted to the harsh desert environment by beginning their breeding activities three months earlier than the main North American population of bald eagles. Breeding bald eagles in Arizona begin courtship in December with nest building or augmentation beginning in January. Eggs, often two but as many as four, are laid in February. The incubation period is 65 days and young hatch around the end of February and into March. Young are then fledged in June at which time they have the mobility to seek suitable shelter from the extreme heat conditions common in July and August.

Beginning in February, nest watchers from the Arizona Bald Eagle Nest Watch Program monitor eagles at selected nest sites. The nest watchers compile data on bald eagle behavior and activities from incubation through fledging. They also inform the public of seasonal breeding area "closures" and monitor the effects of human disturbances in the breeding area. Eagle watchers are trained in identifying emergency situations, such as when an adult leaves a nest with eggs for longer than 60 minutes, when fishing line has entangled an eaglet, or when eaglets have been affected by the parasitic Mexican chicken bug. Through this nest monitoring program, many nesting attempts would have resulted in failure without biologist intervention.

In the Verde Valley, there are currently five active bald eagle breeding areas; Tapco, Green River, Oak, Beaver, and Ladders. The Ladders breeding area has a seasonal closure to protect the bald eagles during the nesting period. Although foot and vehicle travel into this closure area is not permitted, kayaking and canoeing is allowed provided that boaters do not stop within the closure area. News releases are published in the local newspapers each year to inform the public when closures go into effect (December 1) and when closures are reopened (June 30, unless nests fail).

The current known nesting population of Arizona bald eagles continues to expand. Continued protection and monitoring of this unique population of desert-nesting eagles is needed in order to recover the birds to a healthy viable number. The bald eagle is given full legal protection under the Bald and Golden Eagle Act. It is illegal to kill, harm, harass, possess, or remove protected animals from the wild. In addition, entering into "closure areas" may be a violation of the Forest Service Regulations. You can report any violations by calling the Arizona Game and Fish Department at (602) 942-3000 or by calling one of the local Forest Service offices at (928) 567-4121 or (928) 203-7500.