Two beavers, one Canada goose and a crow have been cleaned up at the Medicine River Wildlife Centre and appear to be healthy.
Environment officials have also found three dead fish near the spill site, but won't know for several weeks whether the oil caused their deaths.
A section of pipeline owned by Plains Midstream Canada leaked June 7 near the community of Sundre, spilling up to 475,000 litres of light sour crude into the river.
Carol Kelly, executive director of the wildlife centre near Innisfail, said a baby beaver covered in oil was brought to the centre the next day.
The other animals were delivered later. They will all be monitored there over the next couple weeks — except for one.
A large adult female beaver made a daring escape from the centre Wednesday night.
Kelly figures the animal was able to reach up and hit the exit bar on the door and let itself out. It then chewed through the wall surrounding an outdoor pond. It's now likely roaming the vast wetland that surrounds the building.
"She was obviously doing well," Kelly said with a laugh. "She decided she didn't like this hotel and she left."
Kelly said staff used Pepto-Bismol and other fluids to flush out any oil the animals may have digested. So far, they seem fine.
The animals are eating well and staff will be monitoring their weight.
"We're cautiously optimistic," Kelly said.
Provincial officials earlier asked the centre to remain on standby to treat any affected animals following the spill.
"It's encouraging we've only seen four," Kelly said. "It's been a week now and I think there's a very good chance we won't see an awful lot more. And if we do, it will be sporadic."
Plains Midstream has said high river levels flushed most of the oil downstream into Gleniffer Lake, a man-made reservoir and popular recreational area.
The river is also considered one of the province's premier sport-fishing destinations.
— By Chris Purdy in Edmonton