Answer:
The main function of the sentence "For over sixty years biologists have been watching the island’s moose and wolf populations, recording but not interfering in their struggles" in the paragraph is to provide background information and context.
Step-by-step explanation:
This sentence establishes the historical timeline and approach taken by biologists in studying the predator-prey relationship on Isle Royale. It highlights the long-standing policy of observation without intervention, setting the stage for the current situation where the wolf population is in decline and the ecosystem is imbalanced.