Unmanned Aircraft Examine Pygmy Rabbit Habitat
SHOSHONE • Steady rain tapped the roof of the wall tent Saturday, as Travis Whitley called out a series of numbers.
“Go to 1,500,” he said.
Matthew Burgess read back the numbers as he punched them into a laptop. “Alerion bias one five zero zero.”
A flap on the right wing of the plane twitched, making a robotic sound.
“Disconnect,” Burgess said.
Whitley ran his fingers over a seam between the flap and the wing and called out another number. Burgess kept his eye on a radar image of the weather system churning over the desert north of Shoshone, hoping for a window.
They continued fine-tuning the control surfaces of the aircraft in spite of the wind and rain that would ultimately ground them for days.
Whitley and Burgess are part of the University of Florida’s Unmanned Aircraft System Wildlife Project — the wings beneath a four-year collaborative research effort between the University of Idaho, Boise State University and Washington State University. In its second year, the goal of the researchers is two-fold: create better ways to evaluate wildlife habitat quality while studying pygmy rabbits and their relationship with sage steppe ecosystems.
The deserts of central and southern Idaho are the group’s airfield and classroom.
The Aircraft Challenge
The plane lay belly down on a folding camp table, its wing nearly filling the rear of the tent as Burgess, program coordinator, explained the aerial aspect of the research.
Unmanned aircraft have been used for a long time, he said, primarily by the military. But natural resource users typically don’t work with budgets as large as the U.S. Department of Defense.
“Therefore, one of the driving goals of our program for 14 years has been to build a system that will provide survey-grade aerial imagery on the natural resource user’s budget,” he said.
The 14-pound aircraft was hand built at the university’s hangar facility in Gainesville. The body is a mix of Kevlar and fiberglass. The 9-foot wing is made of fiberglass and carbon fiber and is reinforced with Kevlar.
Burgess said it’s much more practical and cost effective for them to design and build their own planes around their predesigned and preconstructed payloads than to retrofit.
“That was a lesson that took many years to learn,” he said.
The aircraft carries a 10-megapixel digital camera and a high-resolution Global Positioning System and Inertial Navigation System synced to each other and to an onboard computer. The combination allows precise geo referencing of all the imagery.
The computer-programmed flights are not aimed at capturing images of pygmy rabbits on the ground. They are used to map the research area, determine size and amount of available cover and understand the landscape’s thermal dynamics.
“During a flight we have a tremendous amount of information collected,” Burgess said. “We can then take all of that and post process it into individual images or stitch them together into larger mosaics, or whatever the end product needs to be in order to answer the question.”
According to Janet Rachlow, associate professor with UI’s Department of Fish and Wildlife Sciences, that question is: What makes sagebrush quality from a pygmy rabbit’s perspective?
Why Pygmy Rabbits?
Although sagebrush occurs over a broad area in the Northwest, Rachlow said the amount of that area is decreasing rapidly, and — due to things like fire and evasive species — it’s changing. The pygmy rabbit is a bellwether because it’s tightly tied to sagebrush.
The rabbits, which typically weigh about a pound as adults, populate the sage steppes of Idaho and several surrounding states, but their distribution is patchy. They use sagebrush as protection from predators and the elements and for food. In winter, Rachlow said, the rabbits feed almost entirely on sagebrush, which most animals avoid because of its toxicity.
“Pygmy rabbits are really sagebrush specialists,” she said.
Rachlow is working alongside three graduate students on the ground, studying specific dynamics between the rabbit and its ecosystem.
“We’re measuring what these animals do, where they eat and where they go,” she said.
Charlotte Wilson, a UI student, is examining how pygmy rabbits choose habitat in respect to protection from predators and thermal elements throughout the seasons.
Jordan Nobler, from BSU, is looking at plant nutrient and toxicity levels to try to determine how the animals choose where to live and what to eat.
Megan Camp, of WSU, is looking at all dynamics using captive rabbits at an outdoor research facility in Coleman, Wash.
After huddling in the wall tent Saturday, the group left the flight crew behind and walked a muddy road toward a series of sagebrush study plots east of Magic Reservoir.
“I love the way sage smells after a rainstorm,” Wilson said, peeling off into the brush.
Moving from plot to plot, the group documented rabbit tracks, fecal pellets and bite marks on plants, then filled bags with plant samples. Rachlow said the samples represented all three species of sagebrush present and would go to Boise to be tested for nutrient content and toxicity.
The ground studies will combine with the aerial imagery to create a land or wildlife manager’s perspective.
“We are interested in taking what we learn and scaling it up to landscapes or populations, because that is what’s relevant to management,” Rachlow said.
