Like hardy pioneers, the pair of bald eagles nesting at Woods Canyon Lake seem likely to produce enough offspring to one day colonize the Rim Country, according to eagle biologists.
The Woods Canyon pair surprised many experts three years ago by taking over an osprey nest atop a towering snag and starting to crank out eaglets.
This year, they added two more offspring to their tally, part of a record crop of young produced by the state’s desert nesting bald eagles. The young produced by the pioneering pair in the past three years should begin looking for nearby nesting territories in the next year or two — including perhaps other Rim Country lakes like Bear Canyon, Willow Springs and Knoll.
In addition, a pair of bald eagles has been casing Fossil Creek and Chevelon Lake, perhaps with an eye toward establishing a new territory, said Kenneth Jacobson, bald eagle management coordinator for the Arizona Game and Fish Department.
The trend could one day turn Rim Country lakes and streams like Fossil, Tonto and the East Verde into staging grounds for a rare wildlife comeback story.
Arizona eagles set three records this year: The most eggs laid (79), the most breeding territories established (55) and the most young fledged (56). That includes two young eagles produced by the Woods Canyon Lake pair.
The U.S. Fish and Wildlife Service removed the desert nesting bald eagles from the endangered species list more than a year ago, despite efforts by several environmental groups to get the small, but growing Arizona population put back on the list as a vulnerable population that fills a gap in the species breeding range.
A federal court judge has scheduled a hearing on that effort in late November. The San Carlos, White Mountain and Tonto Apache tribes among others have supported that effort, saying the desert nesting eagles have unique cultural significance — even if eagle populations are healthy elsewhere.
Despite the loss of the federal listing, Arizona continues to operate its nest watch program designed to boost the child rearing success of the state’s eagles, many of which live in high-traffic areas like Woods Canyon Lake.
During the spring nesting season, nest watchers keep people away from the nests and call in biologists if a chick gets into trouble — like getting tangled in fishing line accidentally brought back to the nest by the parents.
Jacobson said the watch program has boosted the reproductive rate by an estimated 20 percent by saving chicks. That has played a key role in the expansion of Arizona nesting territories.
Bald eagles generally mate for life and return to the same nest year after year, usually on a cliff face or atop a tall dead snag — most often cottonwoods. Their young hang around the for next several months after they first take flight — usually in about May, depending on the elevation.
Once they’re strong enough, the young head north. They generally find their way to certain summer feeding grounds — like rivers on which salmon or other fish spawn. The young spend the next 3 to 5 years moving back and forth, waiting until the growth of their distinctive white head and tail feathers signals they’re old enough to breed. About 75 percent of the eagles die before they ever reach breeding age, although once they establish a good territory, they typically live for 15 or 20 years.
“We can’t be 100 percent sure, but we think they remain mated for life. However, in the lifetime of an individual eagle, they may have several different mates — when one or the other dies,” said Jacobson.
The Woods Canyon pair in 2008 took over the laboriously constructed nest of two, huge resident osprey, white-breasted raptors only a bit smaller than eagles who also make their living plucking fish out of the water.
Osprey and bald eagles remain ancient rivals for their streamside habitats. Eagles often steal the osprey’s catch and sometimes kill their chicks — but osprey have the satisfaction of a higher reproductive rate and worldwide distribution. The osprey pair the Woods Canyon Lake eagles displaced remain in the area, with the two sets of raptors often cursing one another out through the still afternoons.
Both osprey and eagles at Woods Canyon live mostly on the trout stocked so copiously in the lake, including the fish that escaped fishermen only to die and float to shore — sometimes trailing fishing line. Moreover, careless and uncaring anglers often leave tangles of fishing line on the shore, where it poses a grave danger to all sorts of wildlife — including the eagles.
The adult pair will continue to coddle their young of the year for several months, sometimes feeding them on demand. However, by the time the juveniles return from their first grand tour of Canada and Alaska, the nesting adults will drive them off like any other competitor.
After about four years of wandering around, the young eagles will seek out an unoccupied breeding territory — someplace with big trees or cliffs suitable for nesting and a nearby lake or stream with riffles in which they can spot fish — generally within about 30 miles of their birthplace.
That makes the Woods Canyon eagles and three pairs of eagles nesting along Tonto Creek pioneers whose young will likely spread to a host of Rim Country lakes and streams.
Bald eagles have established breeding territories thickly set along the Verde River and the Salt River, providing another flush of fledglings likely to move into Rim Country in coming years.
The desert nesting eagles had regularly proved more flexible than biologists expected, for instance creating about twice as many breeding territories along the Salt and Verde as biologists expected. The lower Salt and Verde Rivers are packed in now with one breeding pair every three miles. The upper Salt and Verde Rivers boast only one pair for each 12 miles of river front, suggesting many more eagles could squeeze into those areas.
The lawsuits filed by environmental groups like the Centers for Biological Diversity maintain that the desert nesting eagles still need extra protection, since they don’t seem to breed with the large number of other eagles that migrate through Arizona every year. They point out that studies suggest populations smaller than several thousands of almost any species remain vulnerable to sudden shifts and may die out easily as a result of things like disease and drought.