The good news about the oil pipe that ruptured outside Laurel, Montana, last Friday and spilled up to 42,000 gallons of crude oil into the Yellowstone River is that the river is moving, preventing the oil from building up on larger animals like it did in the Gulf Coast spill. The bad news is that it's moving far too fast, spreading the oil as much as 240 miles downstream and splashing it onto shores.
Above average snowmelt has raised river levels tremendously and caused extensive flooding in the area for weeks. The prevailing theory, denied by ExxonMobil officials, is that the raging water itself broke a poorly-buried pipe by throwing debris . Either way, the high waters have significantly hampered cleanup efforts  and it's tough to know, U.S. Fish and Wildlife Services (FWS) officials say, how widely ecosystems will be affected.
The animals of most concern are birds, wildlife biologist Kimberly Dickerson of FWS said in an e-mail, since they collect oil in their feathers, and are poisoned by it when they ingest it.
They can also pass it into their eggs. The International Bird Rescue has set up a shelter for oiled birds, which is happy to take other critters as well, adds toxicologist Karen Nelson. Due to the high waters, the cleanup crew has been mainly relying on aerial observations to pinpoint areas where affected wildlife might be. So far, oiled birds have been spotted and photographed, but none had been caught as of last night.
But raptors such as eagles and osprey are spared a double-whammy: the fish they eat won't be badly affected. Fish, says Dickerson, are able to metabolize the oil and don't retain it in their systems. A bigger concern for fish is whether the oil will plug up their gills, suffocate them, or kill off the algae and insects that the fish eat .
In the meantime, the spill provides researchers a chance to study the broad effects of oil on river ecosystems. Ecologist Alexander Zale of Montana State University, Billings, says that his group has years of baseline data on how fish interact in the Yellowstone River, particularly how they use its side channels and backwaters. "It's just serendipitous that [we've] been doing this because that's the area where the oil is piling up," he says. His group is planning to go out and map how the fish's behavior changes because of the spill -- once the flooding has receded and it becomes safe to launch boats.
It's still unclear how far the oil has spread; disbelieving ExxonMobil's reports, Governor Brian Schweitzer is trying to crowdsource an effort to determine where the oil is going. After the Yellowstone empties into the Missouri River, the oil might even reach South Dakota , although U.S. Geological Survey officials there say it's still too early to tell.