Abstract
The US Fish and Wildlife Service has an interest in understanding how sandhill and whooping cranes (Grus canadensis and G. americana, respectively) use habitats in the landscape surrounding Horicon National Wildlife Refuge in Wisconsin, USA. The refuge and adjacent state wildlife management areas contain the largest cattail marsh in the lower 48 states, providing important habitat for sandhill and whooping cranes, especially for roosting and staging for migration. Important feeding habitats are found in adjacent agricultural fields, small wetlands, and grasslands. It is in these feeding habitats that commercial wind turbines have been erected. We are studying crane movements in this landscape to assess risk of mortality and habitat avoidance associated with wind energy development. A major part of the study is to develop an object-oriented refuging model of how cranes move across and otherwise use the landscape. This is a mechanistic model that simulates the distribution of cranes in the airspace and on the ground using rules about how they use those habitats. Our algorithm uses rules to generate flocks of birds leaving individual roost sites (e.g., size of flock, direction of flight, time of leaving), as well as rules on how flocks select individual fields on the landscape in which to land based on observed habitat use, bird memory, and feeding satiation times. Similarly, movements of birds returning to roosts are also simulated. Data supporting the model are being gathered using both direct field observations and portable radar. We demonstrate how that data are gathered and incorporated into the model.