NEWPORT BEACH — The word traveled downstream by radio: Another sick bird had been found near Upper Newport Bay.

A rescue boat emerged through the salt marshes, and a worker handed Mimi Wood-Harris a rumpled white pillowcase that she cradled in her lap en route to a makeshift rescue station.

Inside the pillowcase lay an eared grebe, still alive but sluggish from a small but toxic oil spill that sent a dangerous sheen this week into the bird-rich waters of the Upper Newport Bay Ecological Reserve.

Rescue workers blame the spill on "midnight dumping" of about 100 gallons of waste motor oil into a storm drain upstream. All day Wednesday, as state Fish and Game workers shuttled these small white bundles of wildlife out of the salt marshes, they talked with restrained but unmistakable anger about such dumping.

What makes the spill particularly vexing for wildlife officials is that although it involved so little oil--enough to fill about three bathtubs--it still made its way into the reserve and proved toxic to bird life.

In her animal rescue work, Wood-Harris has seen much larger environmental tragedies than the one that hit Newport Bay this week. The wildlife toll remains unknown, but as of Wednesday workers had found three birds dead and eight others sickened.

Wood-Harris spent 3 1/2 months in Alaska in 1989, aiding birds in the wake of the Exxon Valdez oil spill. But while this week's spill was relatively small, she said, it occurred precariously close to the sensitive ecological reserve.

"It was maliciously done," said Wood-Harris, the Southern California regional representative for the International Bird Rescue Research Center, a nonprofit group. "People should not just dump their oil. It causes devastation."

Oil was barely visible on the black-feathered American coot that a rescue worker brought to a bay-side state Fish and Game Department office in Newport Beach.

But when Wood-Harris brushed the feathers on the bird's neck, they clumped unnaturally. And the bird was acting unusually listless, she said. The fact that rescue workers could catch these birds suggests that they are weakened, she said.

"These guys can run like nobody's business," said Wood-Harris, watching the coot closely. "He's ingested it, and he's weak."