  We study the problem of placing wildlife crossings, such as green bridges,
over human-made obstacles to challenge habitat fragmentation. The main task
herein is, given a graph describing habitats or routes of wildlife animals and
possibilities of building green bridges, to find a low-cost placement of green
bridges that connects the habitats. We develop different problem models for
this task and study them from a computational complexity and parameterized
algorithmics perspective.
