Why a mountain gorilla family trek allocated on the day of trekking

On the trekking day, every group of 8 people is assigned to gorilla families to trek. Mountain gorillas are used to move deep into the forest searching for food, this makes it difficult to allocate a gorilla family before.  Every evening, park rangers or trackers go deep into the forest to mark where different gorilla families will sleep, and then the next day, they go very early in the morning to check on them, and they go back to the park office to tell them about where to find mountain gorilla families on that day. This helps park management to know a gorilla family one can manage to trek but it depends on the location of the gorilla family, physical fitness plus others. These are factors one should consider while choosing a gorilla family to trek as below;