The next time a cattleman cuts twine from bales he’s feeding and wraps the lengths into a ball to throw into the back of his pickup, Marco Restani and Larry Rau hope ospreys come to mind.
Ospreys, aquatic birds that hunt mostly fish, frequently build huge nests atop tall structures such as electric poles. They settle in open areas, including fields and pastures. In these nests, especially in cattle-feeding areas, the birds weave in baler twine found along roadsides or in pastures.
Nearly 5% of osprey nests along the Missouri and Yellowstone rivers in Montana hold used twine that ensnares nestlings, says Restani, a wildlife biologist at St. Cloud State University, St. Cloud, MN. In Saskatchewan research, 12% of all nestlings raised in the study area had been trapped by twine, he says.
“It’s a preventable, nasty way to die,” Restani stresses.
He and Rau, a retired wildlife biologist and farmer-rancher from Rosebud, MT, hope to raise awareness of the plight of these birds. They’d like ranchers to make sure used twine won’t fall from the back of their pickups or be left in fields. In other words, they’d like the material to be properly disposed of.
“This is a preventable problem,” says Restani. “It just requires a little more careful management of twine.”
The osprey has had a rough past. From the 1940s to the 1960s, its population declined drastically after ingesting fish contaminated by the insecticide DDT. But once DDT was banned, the species rebounded.
The birds like to collect objects such as brightly colored twine, Restani says. “No one knows why ospreys pick it up. There’s probably some sort of signaling benefit,” either to attract a mate or to repel competition.
But the twine starts to fray in the nest, and “once it starts fraying, the nestlings have a much easier time becoming entangled in it. They basically are trapped in the nest and end up dying if we don’t come along,” he says.
Rau commonly sees “big gobs of orange twine hanging off the nest” by his home.
“I think in a lot of pastures or paddocks, people do a fairly good job of dealing with that twine,” he points out.
“Nearly all farmer-ranchers are conservationists at heart,” Rau adds. “It’s just not paying attention, or carelessness or a lack of an awareness of the consequence.”