Porcupines on the Prairie: How do vegetation, cover, and predators influence occupancy?

The North American Great Plains is an imperiled temperate grassland ecosystem that continues to be reduced by habitat conversion. These system-wide losses coincide with a decline in populations of prairie wildlife, including understudied species that require management. North American porcupines (Erethizon dorsatum Linnaeus, 1758) have a widespread distribution, yet few studies evaluate their ecology in prairie-dominated landscapes. We used a camera trap network (n = 1,340 locations) along streams and at random locations within a prairie-dominated landscape in north-central Montana, USA to assess porcupine habitat associations. We fit single-season occupancy models to evaluate porcupine occupancy as a function of (1) vegetation characteristics, (2) predation risk, and (3) topographic features. We predicted that porcupines here would be associated with riparian woody cover within prairies to provide forage and limit predation risk from mountain lion (Puma concolor Linnaeus, 1771), their likeliest predator. Our results suggest that porcupines are associated with areas of intermediate plant productivity near riparian areas in modest terrain, likely to exploit vegetative food resources and localized woody cover. Managers looking to support porcupines in prairie ecosystems could increase vegetation in riparian habitats through techniques such as beaver (Castor canadensis Kuhl, 1820) dam analogs or grazing exclosures.