Grand County’s fish-abundant lakes, reservoirs and streams make happy hunting grounds for osprey.
The birds occupy water-filled habitat on nearly every continent except Antarctica, with fish being their primary food source. But the brown and white under-bellied raptors are still sensitive to environmental disturbances, which can affect populations. In the 1950s, for example, ospreys populations dropped and became endangered in North America until environmental regulations banned harmful chemicals like DDT. Populations have since soared, but local wildlife biologist Doreen Sumerlin, with the U.S. Forest Service Sulphur Ranger District, continues to monitor the bird.
This year, Sumerlin found that while the number of active nests are up slightly, the chick count is down compared to last year.
“But the trend for the last 20 years is still up, so we’re not too concerned,” Sumerlin said.
Sumerlin uses volunteers and contractors to monitor nests primarily along Highway 34 and the Three Lakes Area. Monitoring found 53 nests this year, which produced 45 chicks. In comparison, 2012 found 50 nests and 64 chicks.
“Most mishaps related to ospreys are related to weather,” Sumerlin said. “They like to be high for nesting so they’re really vulnerable.
Last spring’s late snowy conditions may have been too cold for early egg clutches, resulting in fewer chicks. And violent evening storms with high winds and torrential lighting in early July may have taken a toll as well.
“We actually had one nest blow down out on Harvey Island (in Lake Granby),” Sumerlin said. “But it’s still great – 45 chicks is great and 53 nests is great.”
The Sulphur Ranger District has also partnered with Mountain Parks Electric to build nesting platforms to entice the birds away from utility poles. According to Sumerlin, when ospreys nest they like to be the “highest thing out there.” But as the county’s mature lodgepole pines have died and fallen, utility poles and large transmission lines have become more appealing.
“It’s attractive to them, but very dangerous when they start bringing nesting material to these lines. It can also cause outages,” she said.
Once they notice an osprey trying to build a nest on a utility pole, the U.S. Forest service works to build a nearby nesting platform higher than the pole. Through the partnership, Mountain Parks Electric has provided the labor, equipment and manpower needed to construct the platforms. They place perch guards on the utility poles to discourage birds from going back. Sumerlin said the platforms have been highly successful. The Sulphur Ranger District plans on building three more platforms in October, one at Windy Gap and two more along Highway 34.
“People see them and get the false impression we’re trying to attract more (osprey), but it’s because they’re trying to build nests in a dangerous spot,” she said.
The Sulphur Ranger District relies heavily on volunteers to keep an eye on ospreys as well. Volunteers often enlist because they notice a nest near their home, but monitoring is difficult and requires patience. Having a nest near home is helpful because volunteers can observe their adopted nest every day.
“It’s difficult to get the right vantage point and get a good look at them,” Sumerlin said. “It’s also hard to count the chicks because they’re different sizes — they hatch several days apart.”
Volunteers also help by cleaning and maintaining nest boxes, as well as reporting issues, like when a bird becomes entangled in fishing line. Sumerlin said the Sulphur Ranger District currently has about 15 volunteers, and they’ll happily take on more.
“It’s very helpful for us to know which nests are active, when they begin to incubate,” she said. “Volunteers are really important for the program.”
Area residents interested in volunteering can contact the Sulphur Ranger District at 970-887-4100.