An ongoing problem of ospreys becoming tangled in baling twine has prompted a local wildlife biologist to lead an effort to remove the twine from nests in the Flathead Valley.

Doug MacCarter, known for the osprey studies he and his twin brother conducted on Flathead Lake, said ospreys seem drawn to pick up brightly colored baling twine from farm fields and use it in their nests.

“Twine is a real big problem in the valley,” he said. “It easily tangles in the ospreys’ talons.”

When local farmers and ranchers leave twine in the fields or hang it on fence posts, it’s easy pickings for ospreys.

“They like to line their nests with soft materials,” he said. “But they get tangled in the twine.”

He suggested storing used twine in barns or 45-gallon drums.

The twine is especially bad for osprey chicks. Because of their small size, they are more easily tangled and aren’t able to fly from the nest.

This summer, MacCarter’s brother Don, also a biologist and osprey researcher, discovered a dead, half-grown osprey chick in its nest when he was helping band young ospreys. The chick was completely tangled in twine. In a separate sighting this summer, an osprey was spotted by a passerby hanging from its nest, tangled in twine. That bird died.

At least 10 percent of osprey deaths are due to twine, MacCarter stressed, citing a statistic provided by University of Montana wildlife biology professor Eric Greene.

Greene helped develop a brochure aimed at alerting the public about the dangers of injuring ospreys if the twine is left out in the open. The brochure shows photographs of dead ospreys tangled in the twine and notes that one osprey nest blown down in a windstorm contained more than a quarter-mile of baling twine once the tangled mess was unraveled.

This summer, with assistance from Shawn Richmond, who watches nests regularly to record bird activity, MacCarter surveyed the Flathead Valley’s osprey population in an area bordered by Bigfork on the east side, Kalispell to the north and Somers on the west.

The area included the lower Flathead Valley and northern tip of Flathead Lake.

The survey showed six of 21 nests had twine hanging from the nesting sites.

“Other osprey nests may also have had baling twine within the bowl of the nest that could not be seen by observers,” he noted. “My goal this winter will be to remove the visible, trailing strings of baling twine from six of the previously active osprey nests.”

MacCarter said the twine removal will be done only on nests that are not located on active power poles; only Flathead Electric Cooperative is permitted to perform any work on nests on active poles. The cooperative is helping with the removal effort, he added.

Twine removal started last week. MacCarter has been assisted by Seth Bergman of Bergman Tree Service in Kalispell, Bret Ostedahl of Ostedahl Electric in Kalispell and Chris Hammond, a wildlife biologist with Montana Fish, Wildlife and Parks.

On Thursday the crew checked 10 nests and found “enough twine to do damage to birds” in eight of the 10 nests, MacCarter said. Only two nests were twine-free.

In the Flathead Lake area, ospreys seem to favor platform nesting structures. MacCarter’s survey showed 86 percent were active platform nests and 14 percent of the nests were in trees.

While 21 nests were located during the study period, only 19 nests were used this year, he said. Six nests contained one nestling; nine contained two chicks and three nests had three chicks. There were a total of 33 nestlings, 29 of which successfully fledged, an 88 percent success rate.

Anyone wanting to help with observing osprey nests or for more information is encouraged to email projectosprey@mso.umt.edu.

Features editor Lynnette Hintze may be reached at 758-4421 or by email at lhintze@dailyinterlake.com.