By Alex Dobuzinskis

LOS ANGELES (Reuters) - Crews hoping to contain a deadly wildfire burning in rugged, drought-stricken terrain north of Los Angeles made steady progress on Wednesday, after a bulldozer operator fighting a smaller blaze in central California died when the tractor overturned.

Some 3,000 firefighters battling the so-called Sand Fire in the Angeles National Forest extended containment lines around 40 percent of the 38,350-acre (15,520 hectare) on Wednesday, according to fire information officer Sam Wu.

The blaze has destroyed 18 homes as it churned through drought-stricken chaparral and brush spewing out plumes of smoke that prompted the South Coast Air Quality Management District to warn residents in parts of Southern California to avoid outdoor activities.

About a dozen exotic animals displaced by the blaze began returning to a sanctuary in the Los Angeles suburb of Sylmar on Wednesday.

"We've had eyes on them every day so we've known that they're all fine," Martine Collette, founder of the Wildlife Waystation, said of the animals. "How traumatic was it? Well, think about it, they almost burned to death here because the fire came on so fast and I don't know how we escaped it but thank God we did."

About 300 miles (480 km) to the north, a smaller blaze dubbed the Soberanes Fire continued to threaten some 2,000 properties after destroying 20 homes on Sunday in an area between Big Sur and the scenic coastal town of Carmel-by-the-Sea, officials said.

Firefighters were told about the bulldozer operator's death before they headed out early on Wednesday, fire Captain Richard Cordova said. "It makes it real what this job is really about and how dangerous it is," he said.

Officials said the bulldozer overturned and that the operator was a private contractor. A second bulldozer also overturned while battling the flames, but that operator was uninjured, officials said.

The Soberanes Fire has scorched more than 23,500 acres (9,510 hectares) at the edge of the Los Padres National Forest since breaking out on Friday and was about 10 percent contained on Wednesday.

In Los Angeles County, a man killed in the Sand Fire was identified as Robert Bresnick, 67, whose body was found Saturday inside a burned-out car in a driveway, county officials said.

Acting California Governor Tom Torlakson, filling in for Jerry Brown, who is at the Democratic National Convention, declared a state of emergency on Tuesday for the counties where the fires are located.

(Additional reporting by Alan Devall and Dan Whitcomb in Los Angeles and Brendan O'Brien in Milwaukee; Additional reporting by Curtis Skinner; Editing by G Crosse and James Dalgleish)