A forest fire in southern Spain forced the evacuation of at least 1,000 people and threatened a national park famous for its biodiversity and endangered species, authorities said Sunday.

The fire started on Saturday night on Spain's southern coast, then advanced east to reach the Donana Nature Reserve, one of the country's most important wildlife sanctuaries and a UNESCO World Heritage site since 1994.

"The fire has entered in the limits of the reserve, and that is where we are focusing our efforts," Jose Gregorio Fiscal Lopez from the regional Andalusian authority in charge of the environment told Spanish national television.

The reserve protects over 107,000 hectares (264,403 acres) considered of extreme ecological value for their mix of ecosystems, including wetlands, dunes, and woods. It is a key stop for migratory birds and home to a variety of animals, including about a fifth of the 400 remaining Iberian lynxes.

Ecologists who work in the park are concerned that the fire could wipe out some of the area's prized species and terrain.

"We are worried because the impact could be huge," Carlos Molina, an ornithologist who works inside the reserve, told The Associated Press by phone from his home nearby.

"Donana is probably one of the most important areas for birds in all of Europe, and we just happen to be in a nesting season for several species," Mr. Molina said.

While Molina said the reserve's endangered Iberian imperial eagle should not be in danger, the area in immediate threat from the fire is territory for the extremely endangered lynx.

Juan Sanchez, director of the Andalucia's forest fire prevention unit, said the fight was "in its critical phase" due to strong winds whipping up the flames.

"Right now the fire is developing how we expected. The wind is shifting, gaining strength, which is normal as we get to the afternoon," Mr. Sanchez said. "We are managing it, but a change in the direction of the wind could alter the situation."

Susana Diaz, the regional president of Andalusia, said no people have died in the blaze and "there's no risk to the population" after about 1,000 were evacuated from campsites and houses near the town of Moguer, where the fire started on Saturday night.

Ms. Diaz said fighting the fire was proving difficult due to hot, dry weather, with temperatures reaching 102 degrees F., and shifting winds. Over 550 firefighters, soldiers, and police officers supported by 21 air units were combating the blaze Sunday.

"It's still very early, but we are not ruling out the human factor" as a possible cause of the fire, said Diaz.

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Spain's interior minister, Juan Ignacio Zoido, said from a control post near the fire that since "we are taking special measures, even though the wind is pushing the fire toward [the reserve] to keep the damage to a minimum."

The fire comes a week after wildfires killed 64 people in neighboring Portugal, which like Spain is suffering from a lack of rain and high temperatures.