Golden Eagle Research Is New And Strong

Golden Eagle Research Is New And Strong

by Jeremy D. Krones

A golden eagle nest in Diablo Canyon, taking during a survey in 2016.

The Flying M and Bar T Bar ranches are home to a great number of animals, from the fish in the lakes to the bears on the mountain to the eagles in the sky. Both bald eagles and golden eagles live on the ranches, nesting, breeding, and hunting throughout ‘Diablo Country.’ At least one pair of breeding golden eagles live south of the Hopi 3 Canyon Ranches in Diablo Canyon, the boundary between the Flying M and Bar T Bar ranches.

Despite being relatively similar in size and scope to bald eagles, there is little historical data on golden eagles in the western United States, compared to the amount of data state and federal agencies have on the national bird. There have been concerted efforts over the last 15 years to survey and assess the golden eagle population of Arizona by both the Arizona Game and Fish Department (AGFD) and the Hopi Tribe.

Kenneth “Tuk” Jacobson, the Raptor Management Coordinator for AGFD, explains that there werestate surveys to find and document golden eagle populations in the late 1970s. The surveys ended shortly after and were not reinitiated until 2006, just prior to the removal of the bald eagle from the endangered species list. The 2007 Bald and Golden Eagle Protection Act maintained protection to eagles by prohibiting any activities that impact the survival and productivity of the birds.

Golden eagle in flight (photo by Tuk Jacobson)

The Hopi Tribe also conducts regular assessments of golden eagles, led by Darren Talayumptewa, the Director of the Wildlife and Ecosystems Management Program under the Department of Natural Resources for the Hopi Tribe. The eagle assessment surveys are performed on Tribal lands, the Hopi 3 Canyon Ranches, and in breeding areas on neighboring ranches to the Hopi 3 Canyon, which include the Flying M and Bar T Bar.

The Hopi-led surveys began in 1998 but their design was not finalized until 2006, with the help of Dan Driscoll, bald and golden eagle biologist with the American Eagle Research Institute. The Tribe’s surveys were started because of a concern that the ceremonial use of the eagles was contributing to their decline. The Hopi Tribe uses golden eagle feathers for both ceremonial regalia and as offerings at key times throughout the year, such as the winter solstice. Through their surveys, both the Hopi Tribe and AGFD have found Arizona's golden eagle population to be much larger than previously documented.

When the AGFD golden eagle surveys began in 2006, Tuk admits that AGFD did not know nearly as much as they should have, 40 years after the first surveys were performed. Over the last ten years much has been done in Arizona to increase and enhance AGFD’s general understanding of golden eagles. For example, the Southwest Golden Eagle Management Committee was formed in June 2010 to further the efforts of learning more about the birds and their lives in Arizona, and by January 2011, the committee had acquired enough funding to start a state-wide helicopter-based golden eagle nest inventory. Occupancy assessments began in 2013, to measure what nests were being used, and by whom, and productivity assessments began in 2015.

Surveying on neighboring ranches by the Hopi Tribe began in 2012, when Darren’s researchers noticed some of the Hopi 3 Canyon birds flying on the Bar T Bar and Flying M ranches. Darren received permission from the ranches to perform visual surveys of the birds, and then to perform aerial surveys with helicopters. The Hopi Tribe and AGFD collaborate on eagle projects and monitoring, and share data.

It is documented that there are 250 occupied golden eagle breeding territories in the state, not including those on tribal lands (which make up nearly a quarter of Arizona). There are likely more to be discovered. In comparison, there are only about 65 bald eagle breeding territories.

Golden eagles are active hunters and apex predators, which means they are at the top of the food chain. In ecology, that also means the health of their population is tied to the health of the environment around them, such as the populations of small and medium-sized animals and the vitality of the plant matter those creatures eat. In contrast, bald eagles are primarily passive hunters, or scavengers.

Also, golden eagles are not as tied to waterways as bald eagles, which contributes to their relatively large population in Arizona – despite golden eagles being more than four times as populous in Arizona as bald eagles, the national bird is more numerous nationwide.

Much like other predators, golden eagles tend to mate for life, and pairs will build a nest and use it for several years. Sometimes they will build another nest nearby and use it in alternating years. That practice continues over time, so one breeding pair might have a dozen different nests in one area. Based on the size and number of nests, the pair in Diablo Canyon is estimated to have been there for 30 years!

Golden eagles can be very territorial birds, and can even be more sensitive to intrusions than bald eagles. While aircraft doesn’t bother them much, hikers and climbers will. Their actions also change based on the season: during breeding season, the eagles prefer not to get off their eggs unless absolutely necessary, which Tuk defines as a disturbance within a couple hundred yards from the nest. Later in the breeding season, however, the birds will be more apt to leave the nest due to a disturbance because the nestlings do not need round-the-clock care anymore.

The Diablo Canyon eagles nest near a pasture that Bar T Bar has used for calving large numbers of cows for over 30 years. That means that from March 1st through April 15th every spring, there is a regular flow of four-wheeler and horseback activity. These activities do not bother the Diablo Canyon eagles because those activities usually take place at least a half-mile from the canyon edge.

Since the canyon walls block the line-of-sight from the nest to what happens on top, the birds do not get concerned. The eagles are also estimated to have moved to the area after the neighboring pastures were already established, so the eagles are used to the activity. Also, calving provides a ready supply of food for the birds, such as afterbirth and the occasional (and unfortunate) dead calf, at a time when it is especially important for the birds to have a good food supply.

On the Hopi Reservation there is a one-mile ‘no construction’ zone around all breeding locations, and a one to two-mile no disturbance zone around sites. After the breeding and reproduction season is over (in late May to early June), some development activity can start again, but the goal is to minimize the amount of activity in the area year-round. Acknowledging that some of the Hopi ranches and lands are open to recreational activities, Darren explains, “We strive to be good neighbors, and good stewards of the land.”

Likewise, it is important for the public to pay attention to the eagles. Tuk laments, “The public generally loves eagles, but oftentimes they love them to death.” If anyone happens to come across an eagle nesting area and the eagle can be seen, either in the nest or flying around and vocalizing, the best action is to leave the area and report the eagle to both the landowner and the AGFD, and the Hopi Tribe if the eagles are seen on their lands. “Leaving them alone really helps them out,” says Tuk, and reporting their presence helps further our understanding of these beautiful, powerful birds.