The first census of critically endangered mountain gorillas carried out by government authorities since rebels seized the area shows that 10 babies have been born in the last 16 months, wildlife officials said Monday.

The fragile habitat in the Central African highlands, which is home to some of the world's last remaining mountain gorillas, was overrun in 2007 by rebels and soldiers and transformed into an off-limits war zone.

A deal between the insurgents and President Joseph Kabila's administration late last year paved the way for staff who had fled the fighting and rebel occupation to return to Virunga National Park.

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In an eight-week census conducted by the Congolese Wildlife Authority that ended last week, rangers found that 10 baby gorillas had been born since August 2007.

It found the park's habituated population in Virunga National Park had increased from 72 to 81, including the infants and two females that had not been identified previously. However, three gorillas counted in the park's 2007 census are now listed as missing, officials said.

"We're extremely encouraged but the threats remain," Virunga National Park spokeswoman Samantha Newport said.

In the months before insurgents first seized the area in 2007, 10 mountain gorillas were killed by unidentified attackers.

It was the apes' bloodiest year on record since famed American researcher Dian Fossey first began working in Congo in the mid-1960s to save them. The rangers don't know for sure who killed the gorillas, but they believe illegal charcoal traders are trying to sabotage the park for easier access to its trees.

There are only about 720 mountain gorillas left worldwide, according to Virunga National Park, with about 380 of those in the Virunga Volcanoes Conservation Area that is shared by Congo, Rwanda and Uganda.