Area osprey population may be on the increase |

Area osprey population may be on the increase

Janet Urquhart
The Aspen Times
Aspen, CO Colorado
Janet Urquhart The Aspen Times

EMMA – Wildlife officials and bird watchers were quick to notice when a pair of ospreys began building a nest atop a utility pole in Emma recently, but the impressive raptors have apparently taken flight.

It’s not the first time ospreys have started a nest there, above the Roaring Fork River, and then abandoned the site, according to wildlife biologist/consultant Jonathan Lowsky of Basalt-based Colorado Wildlife Science LLC. The good news, he said, is it appears a growing number of the birds is establishing nesting sites in the Roaring Fork Valley.

“Anytime you have a species that is returning and increasing in number, it makes you feel you’re doing something right,” he said.

Area wildlife officials observed the first known pair of breeding ospreys in the valley when they began nesting along the lower Roaring Fork River, between Carbondale and Glenwood Springs. The birds built a nest atop a power pole in 2003; utility workers removed the makings of the nest, added a raised platform to the pole to keep them from being electrocuted, and put the nest back. The pair returned in 2004 and in the years afterward; their first fledglings were observed in 2005. That pair, said Lowsky, still returns, but subsequently built a new nest nearby.

Another pair showed up several years ago and began building a nest on the pole near Emma, just downvalley from Basalt, but then disappeared. Shortly afterward, ospreys were observed building a nest near Rock Bottom Ranch, along the Roaring Fork River below Basalt.

“My guess is that the ospreys that started building the nest at Emma moved over to Rock Bottom Ranch,” Lowsky said. Those birds have returned annually and are nesting there again this year. The latest ospreys to show up at the nest site in Emma are, Lowsky believes, yet another pair.

And, he has received an unconfirmed report of a pair of ospreys near Ruedi Reservoir.

Ospreys appear to be fairly tolerant of human activity, but it’s possible a lot of action on the bike path located right below the nesting site at Emma drove that pair off, Lowsky said. The nest is also within clear view of Highway 82 and not far from a construction project at the historic Emma Store buildings.

If the birds have given up on the Emma nest, they’re probably at work on another nest elsewhere in the area, he added.

U.S. osprey populations were decimated in the 1960s by the use of DDT, which also took the country’s bald eagles to the brink of extinction. Ingestion of the insecticide resulted in eggs with thin shells that cracked and broke, crippling the birds’ ability to reproduce. Both eagles and ospreys have made a dramatic comeback since use of DDT was banned in the States in 1972, but the appearance of ospreys locally is a relatively recent phenomenon.

New lakes and ponds built for irrigation and then stocked with fish, particularly on state’s eastern plains, have likely helped fuel the species’ recovery in Colorado, Lowsky said. On the Western Slope, big rivers attract the birds, which feed exclusively on fish.

The large brown and white raptors are known for their spectacular dives to snare their food.

“If you’ve ever seen one catch a fish, it’s particularly exciting,” Lowsky said.

“I think it’s a good sign when you have an indicator species, a fish-eating bird – it speaks to the health of the river,” said Rick Lofaro, executive director of the Roaring Fork Conservancy. “It’s a testament to the fishing here.”

Local anglers, Lofaro added, should welcome the presence of ospreys as a sign of a healthy trout population.

“It’s the natural way of things,” he said. “The fish aren’t solely in the river for us to catch and release.”

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