Final answer:
Homo erectus at Choukoutien likely exploited multiple mammal species.
Step-by-step explanation:
Homo erectus exploited mammal species at Choukoutien. The exact number of mammal species that Homo erectus exploited at Choukoutien is not mentioned in the information provided. However, there is evidence that Homo erectus at Zhoukoudian, China was hunting, cooking, and eating meat, and the remains of Homo erectus were prey to animal scavengers such as hyenas. This suggests that Homo erectus interacted with various mammal species to fulfill their dietary needs.