Beyond protected areas: Private lands and public policy anchor intact pathways for multi-species wildlife migration

Migration is a critical strategy in maintaining populations, and pathways used by individuals lend insight into habitat quality and connectivity. Yet sustaining migration among large-ranging wildlife poses a challenge for conservation, particularly among landscapes that include a diverse matrix of land tenure. Such is the case in the Northern Great Plains (NGP), a sagebrush (Artemisia spp.) steppe and grassland ecosystem that is home to the longest-ever recorded migrations by both pronghorn (Antilocapra americana) and greater sage-grouse (Centrocercus urophasianus). Here, we identify migratory pathways for both species, and measure the ability of current conservation and policy to maintain cross-taxa migration in the face of continued cultivation. Migratory behavior was similar between species in their timing and duration of migration, and in their use of stopovers along the way. Large and intact private and public working lands largely underpinned migratory pathways, whereas protected areas provided another 5% of habitats. Most pathways for sage-grouse were within state- and federally-designated sage-grouse Core Areas, which contain regulatory caps on anthropogenic disturbance on public lands and help guide conservation efforts; these benefits extended to over half of pathways used by pronghorn. Among private lands, both species largely migrated through intact grazing lands, including many that were already perpetually protected from cultivation with conservation easements. Optimization of remaining private parcels provides managers with a spatial tool to prioritize private-lands conservation, and suggests that comprehensive conservation of shared migratory pathways for pronghorn and sage-grouse in the NGP is within reach of completion given the ongoing pace of conservation.