Local ospreys mature rapidly, prepare for long, lonely migration
September 8, 2016
Steamboat Springs — There are signs that Steamboat's first osprey family is about to vacate its affordable housing unit on the Yampa River Core Trail and head south to spend the winter in milder climes. For the three chicks that hatched in early July, that means a crash course in fishing.
Yampa River Botanic Park founder Bob Enever, who has kept a close watch on the osprey parents and their three chicks since they set up housekeeping on a man-made nesting platform just outside the park's river-side entrance, reported this week that the osprey chicks have begun using their own talons to catch fish on their own.
And there is little time to waste in honing those skills.
Dr. Allan Reishus of Craig, who was instrumental in establishing a string of osprey nesting platforms along the Yampa from Moffat County to West Routt, confirmed that osprey chicks make their first migration on their own, without the accompaniment of their parents. If they hope to make it to subtropical Mexico or beyond, for the winter, they have to become self sufficient in the skills associated with diving for fish. Scientists say ospreys feed almost exclusively of fish.
"The young of the year have got to feed themselves within a couple weeks of learning to fly," Reishus said. "The parents will feed them for approximately two more weeks and then they migrate separately."
Enever observed this week that the chicks had begun successfully diving for fish on their own, but were also depending on their parents for some of their daily diet.
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"They're still being fed by the adult male and still being protected by the adult female," Enever said.
It's not clear that wildlife biologists understand precisely how the juvenile birds know how to find their wintering grounds, or for that matter, how the females manage to return to the vicinity of their birth nest after spending back-to back winters in the south before mating for the first time.
Alan Poole, writing for the Cornell Ornithology Lab reports juvenile ospreys are apt to wander and take longer breaks in mid trip than do adults. Birds hatched in the eastern U.S. may even spend more time in flight over stretches of ocean than necessary.
"Adults fly faster and more direct routes, and are more sure of where they're headed," Poole reported.
Ospreys hatched in Colorado are less likely to fly over open ocean on their migration to Central and South America, often stopping on the Mexican Gulf of Mexico.
In his 2010 article, Poole emphasized that it had just been in the previous two decades that scientists had been able to track te migrations routes of individual ospreys thanks to the development of tiny solar-powered staellite transimitters that can be attached to the back of adult birds.
That allowed him to report on a three-month-old osprey that had spent the summer in Massachusetts and was tracked flying 2,700 miles over 13 days from Martha's Vineyard to French Guiana in South America.