The osprey, a common bird of prey found around the world, builds big nests near rivers, lakes and bays. Some of these large raptors line their nests with discarded baling twine or fishing line, but this habit can kill them.
U.S. biologists, including University of Montana professor Erick Greene, are working with ranchers and at boat ramps to keep the attractive nuisance out of the ospreys' clutches.
Greene, resident ecologist with the Montana Osprey Project, has surveyed osprey nests in his home state and across the northwest. In all those places, he discovered nests festooned with brightly colored plastic twine.
“Basically, wherever you’ve got agriculture, hay fields, livestock - which is a lot of the West - you have baling twine, which is used to tie up hay bales, and you have ospreys,” Greene said.
Biologists don't know why the fish hawks are particularly fond of soft, frayed rope, which they use it in place of lichens or grasses in their nests.
It’s sometimes a fatal attraction.
“It looks as if anywhere between 10-to-30 percent of osprey chicks and adults in some areas that are particularly hard hit are killed by this baling twine," Greene said. "The entangled raptors can suffer gruesome deaths by strangulation or starve because they can’t fly off to fish."
That is, unless someone comes to the rescue or, better yet, gives a nest what Greene calls a preventive “haircut.”
He enlists a bucket truck and a crew of linemen from the Missoula Electric Cooperative, and they head to a nest with chicks. It’s on top of a power pole in the middle of a ranch by the Clark Fork River. It's a nest Greene has been worried about for years.
"It has killed a lot of ospreys over the years. This is going to be a good one to clean up," he said.
Lineman George Porter leads a team up to the nest with scissors.
Strands of orange string drape from the wide bowl of sticks like Christmas tinsel. Soon, any unnatural nest material will be removed by snipping and tugging.
It appears as if the ospreys tied knots in the nest.
"That’s basically what it looks like, all tangled,” Porter said. “Yeah, they definitely use it to hold everything together.”
There are multiple kinds of twine in the nest, including a piece of black nylon rope.
The osprey parents squawk anxiously in the background, but they circle at a distance and don't interfere with the quick cleanup of their nest.
The preferable solution, of course, would be to keep twine and fishing line out of nests in the first place.
In Idaho, the state Fish and Game Department and its local partners are placing periscope-shaped recycling bins for fishing line at boat ramps. State wildlife biologist Beth Waterbury also worked on setting up a baling twine pick up and recycling program in her area.
“It’s a logical solution," she said. "I think it is going to make a difference for the incidence of entanglement.”
In western Montana, student researcher Amanda Schrantz did public outreach to farm groups and individual ranchers. She says many had no idea about the lethal effects of discarded twine or the pressing need to collect and store it out of sight.
Schrantz says if just one ranch or dairy leaves twine in its fields, the ospreys will find it.
“Ospreys will go great distances to pick up this baling twine," she said. "Even though we don’t know why, they are. You kind of have to have 100 percent cooperation with this.”
In Oregon, Colorado and Minnesota, private recyclers of plastics accept used baling twine and hay wrap. They can melt it down into new baler twine or automotive parts. Another company recycles recovered monofilament fishing line into artificial reef pieces.
See a livestream of an osprey nest by clicking here.