The total world population of mountain gorillas has risen to 880, according to census data released last week by the Uganda Wildlife Authority. That's almost a ten percent increase over its 2010 estimate of 786.

The critically endangered mammals live only in two locations, Uganda's Bwindi National Park and the Virunga Massif area, with borders that reach into Democratic Republic of the Congo and Rwanda.

Both populations have had positive trends in population growth over the last decade.

Many mountain gorilla groups have been habituated to human presence and are a major tourist draw. In addition to supporting the important surveillance activities of park staff, visitor revenue has been reinvested into community projects such as wells and schools.