DAKAR, Senegal (AP) — Park rangers in eastern Congo hope to begin searching this week for dozens of mountain gorillas who have not been seen since rebels took control of an area where the critically endangered primates live, officials said Tuesday.

Virunga National Park is home to a quarter of the world’s estimated 800 remaining mountain gorillas, but rangers had to evacuate the area in May because of heavy fighting between a recently formed rebel group and government forces.