When reports came into London Zoo that a wild puma had been

When reports came into London Zoo that a wild puma had been spotted forty-five miles south of Lo...
When reports came into London Zoo that a wild puma had been spotted forty-five miles south of London,中的report为什么要变成复数,后面在解释这个报道的时候不就一件事么,这样的话应该是When a report came into London Zoo.可是原文不是这样..