Mean flea counts from prairie dogs and their burrows in Utah (2000), New Mexico (2010-2012), and Montana (2016, 2019). Prairie dogs were live-trapped, anesthetized with isoflurane, and combed thoroughly for 30 or 45 seconds to remove and count fleas. Prairie dogs were allowed to recover from anesthesia and released at their trapping locations. Randomly selected prairie dog burrows were swabbed for fleas using a plumber’s snake to insert a white flannel-cloth as deep as possible into each tunnel; the cable was shook ~30 seconds, and the cloth was removed from the burrow and quickly sealed in a re-sealable zipper storage bag. Fleas were later removed from swabs and counted. Mean flea counts were calculated for each sampling site, and sampling interval, as the total number of fleas collected (from prairie dogs or burrows) divided by the total number of sampling occasions (combings or swabbings). Funding and logistical support were provided by the U.S. Geological Survey; Turner Endangered Species Fund; Turner Enterprises Incorporated; Colorado State University; Centers for Disease Control and Prevention; U.S. Fish and Wildlife Service; Charles M. Russell National Wildlife Refuge; Shortgrass Steppe Long-Term Ecological Research Project; National Science Foundation; and the U.S. Department of Defense Strategic Environment Research and Development Program.