Recreational trail use alters mammal diel and space use during and after COVID-19 restrictions in a U.S. national park

As human visitation to recreational areas increases, wildlife can alter their space use or activity periods to avoid humans. Short-term or gradual variation in human visitation within and across years makes it challenging to assess species responses. We used data from 156 cameras deployed on and off trails (within 50 m) in Isle Royale National Park (IRNP), Michigan, USA, during 2020–2021 to assess diel activity, temporal overlap, and space use of four wildlife species in response to human visitation and wolves. While visitation in both years was greatest in June–August, there were 338 % more human visitors in 2021 than when COVID-19 pandemic visitor restrictions were active in 2020. Space use for all species decreased within and between years as human visitation increased. From 2020–2021, on-trail animal detections decreased while off-trail detections remained constant. As visitation declined late season, red fox ( Vulpes vulpes ) and wolf ( Canis lupus ) detection rates increased on trails while snowshoe hare ( Lepus americanus ) and moose ( Alces alces ) remained low or declined further. Moose, snowshoe hare, and red fox diel overlap with humans decreased with increasing visitation as animals became more nocturnal. Red fox and moose overlap with humans and wolves decreased from 2020 to 2021. On-trail detections declined when human activity intensity increased while off-trail detections remained relatively constant, suggesting human activity influenced species’ space use along trails only. Reducing visitation during the peak visitor season or redistributing the number of visitors across the overall visitor season could reduce mammalian responses to human visitation.