Research examines quality of landscape cover for prey

By Kathleen Tuck, Boise State University

sage-grouse-nps-90PULLMAN, Wash. – As the two foolish pigs learned before running to their brother’s solidly built house of bricks for safety, when the wolf comes calling, the quality of your shelter is everything.

Animals in the wild have instinctively known this. But changes to their habitat caused by humans, climate change and other environmental influences are creating new “fearscapes” dotted with predation risks.

Imaging technology maps vegetation

To better understand what’s happening, researchers are using innovative imaging techniques to map the properties of vegetation that influence how and when animals use cover from the elements and predators. The data could help dictate land management decisions and landscape restoration.

Backed by several National Science Foundation grants, the project is led by Washington State University graduate student Peter Olsoy, a Boise State University alumnus. WSU professor Lisa Shipley and others are on the research team.

Their findings are published in BioScience, the journal of the American Institute of Biological Sciences, in the paper, “Fearscapes: Mapping Functional Properties of Cover for Prey with Terrestrial LiDAR.”

Mapping, manipulating, comparing landscapes

Pygmy rabbits at WSU.

The report notes that many prey in southwest Idaho (such as pygmy rabbits and sage-grouse) rely on sagebrush vegetation for refuge from predators like badgers and birds of prey. But the increase in invasive plant species is altering the landscape and affecting the ability of prey to find shelter.

Images captured by LiDAR (terrestrial laser scanning) are allowing researchers to compare the landscape from various eye-heights (coyote vs. weasel), positions (standing vs. lying) and modes of hunting (ground vs. air).

Once the data is collected, it can be manipulated to reflect changes in the environment or vegetation structure. How does the area look in summer vs. winter, when leaves are gone and cover is scarce? How does a heavy snowstorm change things? What if conditions lead to slow or accelerated growth of plants?

“That’s the cool part of this,” said Jennifer Forbey, a research team member from Boise State. “We collect the data once and we can manipulate it forever.”

Unmanned aerial vehicles access multiple angles

Mapping the functional elements of vegetation — those that provide concealment, for instance — purely from ground level can be tricky. Such measures are location specific and tend to provide limited data. So the team used ground measurements combined with LiDAR to create a more richly detailed fearscape map.

Using remote sensing, LiDAR targets an object with a laser and analyzes the reflected light to capture an image of the object’s 3D structure.

“It essentially creates a map showing relative risk for an animal based on how well it can be hidden,” said Forbey.

Using unmanned aerial vehicles, the team gathered data from multiple vantage points, representing predator sightlines as well as the visibility of potential predators by prey. Information gathered could help researchers understand how habitat changes can impact the predator-prey relationship.

Findings are foundation for future research

Sage-grouse. (National Park Service photo)

Forbey said the project was conducted as a “proof of concept” model. Creating 3D images of habitats will allow for future work, such as research into the reproductive success of birds like sage-grouse that create visual displays to attract mates.

“We plan to use this technology to assess the most visible locations where male sage-grouse are likely to be seen by potential mates,” she said. “We’ll be able to assess the likelihood of mating success for males according to their location on the breeding ground.”