The phrase "pika populations" refers to the number and distribution of pikas, which are small mammal species related to rabbits. It indicates how many pikas live in a certain area and how they are spread out within that region. Full definition
She is a co-founder of Cascades Pika Watch in Oregon, a collaborative citizen science program to monitor the status and distribution of pika populations in the Pacific Northwest. (aaas.org)
The drier and lower elevation sites in northwestern Nevada showed losses of pika populations. (ucsusa.org)
Hik, who studies a cousin of the American pika — the collared pika — in the central Yukon, saw pika populations plummet during the warm winters from 1998 to 2000. (pikaworks.com)