American pikas (Ochotona princeps) seem to be especially vulnerable to climate change, with recent extinctions of pika populations being attributed to global warming. Incomplete historical location records are currently used to examine changes in pika distributions. A method of determining recent pika distributions in the absence of historical records is needed. Here I report on changes over time of known-age pika fecal pellets up to 36 years old. Predictable changes in diameter, internal consistency, and color of pellets provide a method to approximate the dates of last occupation in patches where pikas have been extirpated.