邦我分析一下新概念英语第三册第一课中一句话的语法.

邦我分析一下新概念英语第三册第一课中一句话的语法.
When reports came into London Zoo that a wild puma had been spotted forty-five miles south of London,they were not taken seriously.
本句中的they是指动物圆的专家呢?还是指这些报告.如果是指代这些报告,那么 they were not taken seriously.是被动语态.
那个对?