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A nestling bald eagle in Arizona. CREDIT: Kyle McCarty.
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How perform researchers song the circulate of untamed animals (particularly birds) that can accelerate heaps of of miles a day? By gently equipping them with GPSs. A group in Arizona outfitted bald eagles (Haliaeetus leucocephalus) with the monitors to own a study their migration patterns. The outcomes proved to be pretty bright and were only within the near past printed within the Journal of Raptor Learn.
Between 2017 and 2023, the researchers tracked 24 only within the near past fledged bald eagles and two nonbreeding adults. While breeding Arizona bald eagles are inclined to stick with reference to their nesting territories for a big selection of of the yr, the circulate of nonbreeding eagles is extra of a mystery. Shedding gentle on this pattern—to boot to any differences of survivorship between nonbreeders and breeders—carries predominant implications for notion the utter of the species.
“Emigration and immigration are sophisticated to explore, so seeing this eagle explore some distance beyond Arizona utter traces used to be spell binding to explore,” Caroline Cappello, a quantitative wildlife ecologist at Cornell University and co-creator of the original be taught about, tells Standard Science.
Contrivance showing distribution of Bald Eagle actions for folk originating in Arizona, USA, all the absolute top contrivance by their migration and nonbreeding seasons. The numbered arrows original well-known migration routes by (1) western Utah, eastern Nevada, and western Idaho; (2) central Utah and eastern Idaho; (3) western Colorado and Wyoming. The inset reveals the US Fish and Natural world Provider administrative boundaries of the Pacific Flyway. CREDIT: Cappello et al. (2025).
For the length of the seven-yr length of time, researchers tracked the person eagles for therefore long because the devices lasted. While many North American migrant birds flee south all the absolute top contrivance by the nonbreeding season within the frigid weather and up north again to nest all the absolute top contrivance by the hotter months, the be taught about’s Arizonan bald eagles adopted a assorted pattern.
They began nesting within the frigid weather and “moved north from Arizona all the absolute top contrivance by the inhabitants’s submit-breeding length within the boreal spring and summer, and returned south in autumn in advance of the breeding season,” the researchers explained within the be taught about. They documented that eagles of all ages traveled to southern Canada and the northern United States, and their migrations changed into extra true with age.
“There are only about a cases where bald eagles banded as nestlings in Arizona had been seen breeding outdoors of the utter,” says Capello. “Most which may perchance well perchance be seen breeding in later years return to Arizona. The female that ranged into northern California confirmed indicators of perchance establishing a breeding territory there, which may perchance well per chance had been vital given how rarely ever this has been documented.”
An adult bald eagle returning to the nest in Arizona. CREDIT: George Andrejko.
A lot of the eagles in ask adopted the previously identified Intermountain Flyway, a migratory route that “ranges from Alaska to Mexico east of the Sierra Nevada and west of the Rocky Mountains and Sierra Madre Occidental,” they added. Cappello and her colleagues’ investigation additionally identified the the same our bodies of water as migratory pitstops for the bald eagles as those previously came across by a be taught about within the Eighties, indicating their multi-generational importance.
One adventurous young eagle crossed 10 states and four Canadian provinces sooner than settling in California, where researchers notion she may perchance well perchance also prefer a breeding territory. Unfortunately, she used to be electrocuted, which is no longer uncommon for excellent raptors admire eagles. This premature fate used to be disappointing for the researchers, on condition that the bird’s uncommon circulate may perchance well perchance also own shed uncommon gentle on the dispersal prospects for bald eagles hatched in Arizona.
Nonetheless, the group mild had a literal bird’s-peer glimpse into the actions of dozens of bald eagles whose revelations will absolutely empower conservationists to higher provide protection to those majestic animals and their migration routes.
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