Exploring relationships between winter tick (Dermacentor albipictus) ecology, moose (Alces alces), and climate in Jackson Hole, Wyoming

Abstract

Global ecosystem changes are affecting how parasites and their hosts interact. Winter ticks (Dermacentor albipictus) are ectoparasites of moose (Alces alces) which can cause anemia, hair loss, and even death due to large numbers of hundreds to thousands of ticks feeding. Warming temperatures are expected to increase winter tick abundance and activity windows while habitat loss and other factors diminish moose nutritional conditions making them more susceptible to complications from tick infestations. Though some of these factors are well- studied in parts of Canada and the northeastern U.S., winter tick, moose, and climate interactions are not well understood in the western U.S. We surveyed winter ticks, moose, and elk in Jackson Hole, Wyoming from 2020-2023 and found elk to be feasible reservoirs for winter ticks, potentially impacting moose infestation rates. In 2021 we deployed scent detection dogs to find winter ticks in the field and determined that they are indeed capable of surveying for winter ticks but do not dramatically outperform the traditional tick drag survey. We found that average maximum temperature and vapor pressure deficit over summer affect winter tick occupancy rates but we did not find climate associations with winter tick abundance over three years of surveys in Jackson Hole. We did, however, find temperature to affect winter tick survival and reproduction in monitoring surveys, implying a potential mismatch between extrapolated climate datasets and conditions experienced by ticks. Finally, we found moose that spend more of their fall home range in 'urban' versus 'rural' landscapes and with higher spring and fall seasonal home range overlaps to be in higher hair loss categories. Future research in winter tick-moose systems, and in tick-borne disease research as a whole, should take into account host movement patterns and the potential impacts of multiple competent host species on the landscape.