Crop raiders in an ecological trap: optimal foraging individual-based modeling quantifies the effect of alternate crops

The First 3 Years: Movements of Reintroduced Plains Bison (Bison bison bison) in Banff National Park

We assessed 3 years of post-release movements of a reintroduced plains bison (Bison bison bison) population for evidence of anchoring, settling, exploratory and adaptive behavior within a 1200 km2 target reintroduction zone in Banff National Park. We first held them in a soft-release pasture for 18 months, then partially constrained their movements with drift fences and hazing trials to discourage excursions from a 1200 km2 target reintroduction zone. Their post-release movements were within 13 km of the soft-release pasture for the first 3 months, but management interventions were needed to keep the animals within 29 km of the release site and inside the reintroduction zone for the remainder of the 3-year study period. Bison exploration was high in the first year but decreased thereafter, as did the size of their annual home range. Step lengths did not decrease but the frequency of “surge movements” (step lengths > 4 km in 2 h) did. Fence visits did not decrease over time but the need to herd/haze the bison from other, unfenced boundary areas did. The reintroduced bison seasonally selected for rugged, high-elevation habitat despite being translocated from a flat landscape. Our results suggest wild bison reintroductions to areas of just a few hundred square kilometres are possible without perimeter fencing, so long as good habitat and management interventions to discourage broad movements are in place. Trends suggest such interventions will need to continue in Banff until the bison range can be expanded and/or bison movements are constrained by other forces, such as regulated hunting outside the park.

The plasticity of ungulate migration in a changing world

Migratory ungulates are thought to be declining globally because their dependence on large landscapes renders them highly vulnerable to environmental change. Yet recent studies reveal that many ungulate species can adjust their migration propensity in response to changing environmental conditions to potentially improve population persistence. In addition to the question of whether to migrate, decisions of where and when to migrate appear equally fundamental to individual migration tactics, but these three dimensions of plasticity have rarely been explored together. Here, we expand the concept of migratory plasticity beyond individual switches in migration propensity to also include spatial and temporal adjustments to migration patterns. We develop a novel typological framework that delineates every potential change type within the three dimensions, then use this framework to guide a literature review. We discuss broad patterns in migratory plasticity, potential drivers of migration change, and research gaps in the current understanding of this trait. Our result reveals 127 migration change events in direct response to natural and human-induced environmental changes across 27 ungulate species. Species that appeared in multiple studies showed multiple types of change, with some exhibiting the full spectrum of migratory plasticity. This result highlights that multidimensional migratory plasticity is pervasive in ungulates, even as the manifestation of plasticity varies case by case. However, studies thus far have rarely been able to determine the fitness outcomes of different types of migration change, likely due to the scarcity of long-term individual-based demographic monitoring as well as measurements encompassing a full behavioral continuum and environmental gradient for any given species. Recognizing and documenting the full spectrum of migratory plasticity marks the first step for the field of migration ecology to employ quantitative methods, such as reaction norms, to predict migration change along environmental gradients. Closer monitoring for changes in migratory propensity, routes, and timing may improve the efficacy of conservation strategies and management actions in a rapidly changing world.