Incorporating field data and habitat use modeling to design and locate wildlife mitigation structures on a highway in Alaska

Nathan Jones, HDR
Simon Wigren, HDR, John Wolfe, HDR
Topic Area
Planning for Transportation Ecology

Highway realignment planning near Cooper Landing, Alaska, included measures to assess existing habitat use and wildlife movement corridors in proximity to the Sterling Highway. Data from VHF- and GPS-collared wildlife were combined with geospatial datasets to model the quality of wildlife habitat and movement corridors across the entirety of the Kenai Peninsula for six focal wildlife species: brown bear, black bear, moose, wolverine, lynx, and dall sheep. In order to validate a localized subset of the models, we deployed 43 Reconyx Hyperfire digital cameras along the Sterling Highway between Quartz Creek and Jean Lake from October 2015 to November 2016. The sampling locations were distributed within and outside of modelled wildlife movement corridors with half on each side of the existing highway. Fine-scale siting of cameras focused on existing wildlife trails or other areas with signs of wildlife activity. Approximately 25,500 photographs were taken over a total of 16,306 camera days. Cameras were operable from 278 to 394 days depending on the date of deployment/retrieval and periods of inoperability. A total of 17 mammal species were recorded. The most common species was human, followed by moose and brown bear. Moose were the most widely dispersed species; they were recorded at all 43 cameras. We identified trends in circadian and seasonal activity, distribution, habitat use, and behavior. This is one of the largest remote wildlife camera-trap studies in Alaska, to date. The results of the camera trap study both validated and refined the model outputs. The results of the camera trap study, combined with habitat use modeling and expert knowledge identified optimal locations for wildlife mitigation structures. Over- and under-crossing structures were engineered within the topographic and design constraints of the four highway alignment alternatives. In May 2018, the Federal Highway Administration selected a highway alignment alternative that will include four under-crossing structures and one over-crossing that are designed to facilitate movement of the focal wildlife species. The structures will help to maintain natural connectivity between seasonal and diurnal habitats and reduce wildlife-vehicle collision rates. The wildlife over-crossing will be the first bridge dedicated to wildlife use in Alaska.

Abstract Keywords
Overpass
underpass
wildlife
Mitigation
habitat use
camera traps
Alaska