Scientists are looking for the presence of mining waste in the Clark Fork River's food chain--specifically, mercury from abandoned gold mines.
Osprey are some of the most watched and photographed wildlife in western Montana, and since they're at the top of their food chain, they may turn out to be very good indicators of certain toxic substances. In this case, mercury.
If you want to check osprey chicks for mercury exposure, you have to go where they are. Which means going up, then bringing the birds down to waiting hands.
From here, researchers follow a familiar pattern. Veteran raptor handler Rob Domenech attaches a leg band, members of the team collect a feather, and Heiko Langner of UM's bio-chemistry and geology lab draws a small sample of blood.
This group of researchers began their work two years ago. With an upward assist from Missoula roofer Dave Taylor. The scientists wanted to study whether mining wastes in the Clark Fork River were entering the food chain, and they believed the osprey could provide answers. Erick Greene:
"The big picture questions really, I think, have to do with using osprey as environmental canaries. They've been really powerful at that," said UM Biology Professor, Erick Greene, "Looking at the chicks tells us a lot about the health of the aquatic system right around that nest."
But tests on osprey blood and feathers revealed that the Clark Fork's most prominent toxins, arsenic and copper, were not an issue -- Mercury was.
And so the scientists began focusing on that toxin. This season, they were greeted with another puzzling surprise.
Domenech: "Preliminarily, we're seeing fewer osprey nesting downstream from the Milltown Dam," said Domenech.
"It looks now like where there was maybe a dozen nests downstream of Missoula, there's only, well, we found only one with one chick," said Langner.
Langner in particular believes the breach of Milltown Dam and the high river flows that followed scoured so much sediment from the Clark Fork and Blackfoot riverbeds that osprey were unable to fish in the muddy water.
"Seems like they didn't have enough food to bring up their young," said Langner.
Ian Marquand: "Should we be worried?"
Greene: "We hope not. But stay tuned. That's really one of the underlying fundamental questions we're trying to get at in this project."
(From July 17, 2008)
This year the return of osprey to western Montana nests also brings the return of visitors to those nests -- Scientists.
In the last couple of years researchers have found osprey with high levels of mercury in their bodies, and now they have a new reason to be concerned.
The osprey research team is now in its third season of field work, and this year the team is opening some of its field trips to children, so they can learn more about osprey.
The field work involves gathering small amounts of blood and feathers from young birds, but the team is finding many nests with fewer chicks, or none at all.
A nest in Lower Miller Creek has had as many as four chicks in past years; this year, there was only one, and it became so weak so quickly, the scientists immediately returned it to the nest before taking any samples.
They said afterward that they were shocked by the chick's unresponsiveness.
"We've never, I've never even heard of that with raptor banding. I've heard of it with grouse, where they get so stressed," said Rob Domenech with Raptor View Research Institute, "but I mean, who knows? There's only one nestling in this nest."
This summer's observations already have led to a lot more questions for researchers, including why the bird was so weak, and why some nests along the Clark Fork have no young in them at all.
We'll have more on that story Thursday.
